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787 Cards in this Set
- Front
- Back
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Does the bourdon gauge measure high or low pressure?
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it measures high cylinder pressures.
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Does the bourdon gauge measure the relative or absolute pressure?
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it measures pressure relative to the atmospheric pressure.
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What is the name of the regulator that is found on cylinder tanks?
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the bourdon gauge.
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What do pressure reducing devices/regulators for cylinders do?
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they reduce the high and variable pressure in a cylinder to a lower pressure, about 40 to 48 psi. Gas flow is maintained constant without changing the supply pressure.
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What do the second stage reducing devices/regulators do?
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they receive gas from either the pipeline or the cylinder reducing device (regulator) and reduce the pressure further to 26 PSI for nitrous oxide and 14 psi for oxygen.
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What is the purpose of second stage reducing device?
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the purpose is to eliminate fluctuations in pressure so that flow remains constant.
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Besides reducing line pressure, what other function does a second stage regulator provide?
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in addition to reducing line pressure, the second stage regulator maintains constant flow with changing supply pressure.
in other words, the second stage regulator eliminates fluctuations in pressure. |
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When the bourdon gauge reads zero, what is the pressure in the tank?
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1 atmosphere.
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Describe the function of the second stage regulator:
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the second stage regulator receives oxygen from a cylinder or wall. The incoming oxygen pressure of 40 to 50 PSI is reduced by the second stage regulator to 10 PSI and then the oxygen is delivered to the flow control valve.
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What is the purpose of cracking compressed gas cylinders?
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the purpose of cracking a cylinder is to clear the soldiers of any dirt or dust before a fitting is placed.
when the cylinder is turned on, the gas enters the yoke and passes through a strainer nipple, which serves as a filter that removes dust particles that may be present on the cylinder valve or the contact surface of the yoke. |
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Which two gases are in liquid form in pressurized cylinders?
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nitrous oxide and CO2.
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What is the working pressure of the hospital pipeline system?
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50 PSI.
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Name 5 common contaminants of medical gas lines:
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oil, water, bacteria, particulate matter, and residual sterilizing solutions.
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Which contaminant of medical gas appliance is most common?
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water.
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How often should cylinders be inspected?
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at least every five years, or, with a special permit, up to every 10 years.
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What agency controls such processes as the filling and manufacturing of gas cylinders?
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the United States Department of Transportation.
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List the responsibilities of the Department of transportation when dealing with compressed gases:
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the Department of Transportation has set requirements for the manufacturing, packing, labeling, filling, qualification, transportation, storage, handling, maintenance, requalification and disposition of medical gas cylinders and containers.
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Who regulates medical gas?
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the United States pharmacopeia national formulary.
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What law does the federal food and drug administration enforce in the regulation of compressed gas cylinders?
What do they do to enforce this law? |
They enforce the federal food, drug and cosmetic act. They inspect medical gas and notification plants every other year.
oxygen cylinders and nitrous oxide tanks have been recalled for numerous reasons including improper labeling, inappropriate testing, filling of cylinders with the wrong gases, and contamination of gases with ammonia, rusty water, oil, or chlorine. |
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What is Woods metal?
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it is an alloy commonly used, composed of varying percentages of bismuth, lead, tin, and cadmium. It is used as a safety relief device (fusable plug.)
it melts at the predetermined temperature to release gas from a cylinder in case the cylinder heats up. |
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What is the pressure in a full E. cylinder of oxygen?
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2200 PSI.
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How many liters of oxygen can be released from a full E. cylinder?
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625 to 700 L.
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How long does it take to empty a fully cylinder of oxygen that is turned on at 5 L per minute?
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slightly more than two hours.
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A full E. cylinder at 800 PSI is connected to a delivery system set to provide 2 L per minute. How long will the E. cylinder supply provide this flow rate?
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there is one third the original volume, or, 208 L of gas remaining. This will last 104 minutes.
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With an E. cylinder, what do pressures of 2000, 1000, and 500 PSI correspond to?
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2000 is full.
1000 is half full. 500 is the one quarter full. |
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If the pressure on an E. cylinder of oxygen reads 700 PSI, how much gas remains in the cylinder?
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210 L.
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At what pressure should the oxygen e cylinder on an anesthesia machine be changed?
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at least half full, about 1000 PSI.
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For which gases can the amount remaining in the cylinder be determined by the reading on the pressure gauge?
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oxygen, air, helium, and nitrogen.
this is because these gases are not in liquid form in high pressure cylinders. |
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How many liters of nitrous oxide can be released from a full E. cylinder?
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1590 L.
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During the case, the wall oxygen pressure fails. The E. cylinder registers 2000 PSI, but within a few breaths, falls to zero pressure. What should you do?
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open the valve on the E. cylinder. The gauge may read 2000 after the E. cylinder was turned off if the pressure and the line was not vented.
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Why might the pressure in nitrous oxide tank fall when the tank is in use even if there is liquid in the tank?
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pressure will fall slowly because the tank cools as nitrous oxide exits. Vapor pressure of nitrous oxide in the tank decreases as temperature falls even when there is liquid in the tank.
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What is the situation when the pressure gauge on a tank of nitrous oxide begins to fall rapidly?
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the tank has no more liquid nitrous oxide.
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What pressure indicates that there is no liquid left in the nitrous oxide tank, and how full is the tank at this time?
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745 PSI. The cylinder is less than one quarter full and there is no liquid remaining.
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Nitrous oxide tank pressure gauge reads 700 PSI. What is the significance of this?
What volume of nitrous oxide is left in the tank when the liquid is gone? |
nitrous oxide pressure below 740 PSI indicates that the cylinder contains no liquid and is less than one quarter full and should be changed.
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What prevents backflow pressure in the gas cylinders?
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valve yokes.
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Explain the purpose of the pin index system:
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the pin index system ensures that the cylinders will be non interchangeable. For example, oxygen cannot be attached to nitrous oxide yoke.
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What size gas cylinders have the pin index system?
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size a (small) through sized E.
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describe the diameter index safety system (DISS) and state its purpose:
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the pipeline inlet fittings are gas specific diss threaded body fittings. This system provides threaded non interchangeable connections for medical gas lines. This minimizes the risk of mis connection.
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What 11 components of the anesthesia machine are required?
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gas inlet.
pressure regulators. oxygen pressure failure devices. flow control valves and flowmeters. vaporizers. fresh gas outlet. spirometer's. reading circuit pressure gauges. ventilators. waste gas scavengers. oxygen analyzers. |
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What are the 6 components of the low pressure system of the anesthesia machine?
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flow indicators.
vaporizers. vaporizers circuit control valves. back pressure safety devices. low pressure safety devices. the common gas outlet. |
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List the nine parameters that the anesthesia machine must monitor in order to comply with astm f 1850 00:
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newly manufactured machines must have monitors that display: continuous breathing system pressure.
exhaled tidal volume. ventilatory carbon dioxide concentration. anesthetic vapor concentration. inspired oxygen concentration. arterial oxygen concentration. oxygen supply pressure. arterial blood pressure. continuous electrocardiogram. |
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Describe the three functions of the interlock system on the anesthesia machine:
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1. Holds 2 to 3 units.
2. The interlock system, also known as the vaporizer exclusion system, prevents more than one vaporizer from being turned on at a time. You cannot deliver more than one agent simultaneously. 3. the interlock system also ensures that all vaporizers are locked in such that leaks are decreased and trace vapor output is minimal when the vaporizer is off. |
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What gas machines generally have machine outlet check valves, drager or ohmeda?
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ohmeda. Most of them have it.
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Where is the machine outlet check valves located?
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downstream from the vaporizers and upstream from the oxygen flush.
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When is the machine outlet check valve open?
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in the absence of back pressure.
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When is the machine outlet check valve closed?
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when back pressure is exerted on it, like with intermittent positive pressure and oxygen flushing.
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What is the purpose of the check valve found at the cylinder inlet to the gas machine?
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the single check valve between the machine and the cylinder prevent retrograde flow of gases from the machine to the atmosphere when there is no cylinder in the yoke.
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List three functions of anesthesia machine check valves:
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prevents backflow from high pressure to low pressure sides (prevents pumping action of gases).
allows for an empty cylinder to be exchanged for a full one with minimal loss of gas. minimizes leakage from an open cylinder to the atmosphere. |
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The check valve found between the cylinders that are double yoked has what purpose?
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this check valve prevents transfer of gas from the cylinder with higher pressure to the cylinder with lower pressure. In addition, one of the double yolked cylinders can be changed while the other is in use.
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Early vaporizer designs were susceptible to a pumping effect. Describe this pumping effect:
When did this most often happen? |
intermittent positive pressure in the circuit, like with ventilation or releasing the oxygen flush valve, caused fluctuating back pressure to be transmitted into the low pressure system. The result of this effect was an increased concentration of anesthetic delivery.
this happened more often with low flow rates. |
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How is the pumping effect prevented in modern anesthetic vaporizers?
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new anesthetic vaporizers incorporate mechanisms that decrease the size of the vaporizing chamber relative to the bypass channel and increase the volume of the inflow channel.
vapor saturated gas cannot make its way back into the bypass channel, and thus, the pumping effect is prevented. |
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What system prevents filling a vaporizer with the incorrect agent?
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the keyed filling ports system prevents this.
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What is the transport "t" dial setting on the drager 20n gas machine?
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it prevents tipping related problems.
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What is the equivalent of the transport "T" dial setting on machines other than themdrager 20n?
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the vaporizer cassette systems on other modern machines provide this function.
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What type of anesthesia machines should be tested with a negative pressure leak test?
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anesthesia machines with check valves should be tested with a negative pressure leak test.
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Where and how is the negative pressure leak test performed on the anesthesia machine during checkout?
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a suction bulb is attached to the common fresh gas outlet and then squeezed repeatedly until the bulb is fully collapsed. The anesthesia machine is leakfree if the bulb remains collapsed for at least 10 seconds.
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Where is the valve for the scavenging system located?
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in the breathing circuit or the ventilator. Either of these valves is connected to hoses leading to the scavenger system.
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To what is the outlet of the scavenging system connected?
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to the outside (with passive scavenging) or to a connection to the hospitals vacuum system (active scavenging).
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What is the purpose of pressure relief valves?
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negative and positive pressure relief valves protect the patient from the negative pressure of the vacuum system or the positive pressure from an obstruction in the disposable tubing.
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What is the purpose of each of the two pressure relief valves of the scavenger system?
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one is for positive pressure and one is for negative pressure.
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When does the positive pressure relief valve of the scavenger system open?
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if flow of waste gas into the vacuum source is insufficient and the reservoir bag distend.
the positive pressure relief valve will open and vent some of the exhaled gases into the room. |
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When does the negative pressure relief valve of the scavenger system open?
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when the flow of waste gas into the vacuum system is too high and the bag collapses. The negative valve opens and lets in room air.
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What would happen if there was too much suction applied to the scavenging system?
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the reservoir bag would collapse.
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What would happen if there is too little suction applied to the scavenging system?
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excessive pressure in the breathing system leading to barotrauma.
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How frequently does the scavenging system need to be checked?
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every day with your machine check.
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Name the five components of the scavenging system:
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the gas collecting system.
the transfer tubing. the scavenging interface. the gas disposal tubing. active or passive gas disposal assembly. |
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What are indications that the scavenging system is malfunctioning?
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increased positive pressure can be transferred to the breathing system resulting in decreased bellows movement from the ventilator.
increased ventilation pressures. desaturation due to decreased fresh gas flows and CO2 buildup. |
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When the O2 flush button is pushed, what is the litre flow rate?
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35 to 75 L per minute.
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In the arrangements of flow meters, where is the oxygen flow meter best located?
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it should be last in the sequence.
this is to ensure against accidental decrease in delivered oxygen concentration. last is the farthest to the right in the United States. |
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Why do some modern gas machines have two flow meter tubes whereas other machines have one flow meter tube?
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2 tubes allows you to titrate both high and low flow rates with the same flow meter.
single flow meter tubes has dual tapers in the tube, one for low flow and one for hi flow. |
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What is the fail safe system design to do?
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prevent delivery of hypoxic gas mixtures.
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Does the fail safe system operates on the basis of pressure or flow?
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is activated by low pressure.
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When does the fail safe system shut off flow of all gases?
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it shuts off or proportionally decreases flow of all gases when the pressure in the oxygen delivery line decreases to less than 20 to 30 psi.
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At what pressure does the fail safe valve shut off the flow of nitrous oxide or other gases?
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line pressures of 15 to 30 psi will usually close the flow of all gases, except oxygen, to the common gas outlet.
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Which anesthetic gas has no fail safe valve?
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oxygen.
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During the case, the machine shuts down all non oxygen gas flow. What happened?
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the oxygen pressure fell below 25 to 30 psi. When oxygen pressure falls below 25 to 30 psi (roughly 50% of normal) the faill safe valve automatically closes nitrous and other gas lines to prevent delivery of hypoxic mixtures of gases.
A gas whistle or electrical alarm sounds to alert the anesthetist to this occurrence. |
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What dos it mean when the oxygen low pressure alarm sounds?
What do you do? |
this means there is a profound loss of oxygen pipeline pressure.
fully open the E. cylinder, disconnect the pipeline, and consider the use of low gas flow. |
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What type of flow meter uses rotameters?
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variable orifice flow meters.
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What is thorpe tube?
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it is a tapered (variable orifice) tube with an indicator bobbin that is part of the constant pressure variable orifice flow meter found in anesthesia machines.
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Describe the tapering of the thorpe tube and the location in the anesthesia machine:
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the smallest diameter is at the bottom of the tube and the largest diameter is at the top.
it is located in the manifold area of the anesthesia machine. |
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What is the purpose of a proportioning system?
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proportioning systems have been placed on newer anesthesia machines to prevent delivery of hypoxic gas mixture. The delivery of nitrous oxide and oxygen are linked. The minimum concentration of oxygen that could ever leave the common gas outlet is 25%.
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How does the proportioning system work?
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nitrous oxide and oxygen are interfaced either mechanically or pneumatically so that the minimum oxygen concentration is 25%.
the proportioning system lowers the delivery of gases other than oxygen to keep the delivered oxygen concentration above 25%. |
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When does the proportioning system alarm go off ?
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the alarm will sound when the nitrous oxide/oxygen mixture falls below the low limit.
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How often should a complete test of all the anesthesia apparatus be performed?
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at least each day before the first case.
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Give six examples of how of vaporizer can become hazardous:
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incorrect anesthetic.
bypass chamber contaminated with liquid anesthetic if the vaporizer is tipped. simultaneous administration of two anesthetics if the interlock mechanism is not working. development of leaks. contaminated liquid anesthetic placed into the vaporizer. over filling of the vaporizer. |
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?? need to conform this answer
If the vaporizer is calibrated at sea level, will the amount of anesthetic delivered at high altitude (Denver Colorado) the greater, the same, or less than the dial setting? explain: |
the percent going to the patient is more than the dial setting in the situation.
consider the formula: vv=[(cf) x (vp)]/(bp minus vp) at high altitude, the barometric pressure is decreased so the denominator of the equation (bp minus vp) gets smaller. Because we are dividing by a smaller number, ratio increases to the volume vaporized is higher. this means that the percent going to the patient (i.e. volume vaporized divided by total flow times 100) is increased. |
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A vaporizer is calibrated in Denver Colorado and set to deliver 1.5%, and a vaporizer is calibrated at sea level and set to deliver 1.5%. Will both patients the anesthetized to the same depth?
explain: |
the patient in Denver will not be as deep.
atmosphere pressure in Denver is 670 mmHg so the partial pressure of anesthetic going to the patient at 1.5% will be 10.5. atmosphere pressure at sea level is 760 mmHg, so the partial pressure of the anesthetic delivered at 1.5% will be 11.4 mmHg. |
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The flow compensated vaporizer compensates for what?
how? |
temperature.
it is equipped with an automatic temperature compensating device that helps to maintain a constant vaporizer output flow over a wide range of temperatures. |
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What volatile agents are delivered from variable bypass vaporizers?
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isoflurane, enflurane, halothane, and sevoflurane.
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Name three characteristics of modern day variable bypass vaporizers:
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they are agent specific.
they are temperature compensated. carrier gas flows over the anesthetic liquid in the vaporizing chamber. |
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Explain the concept of carrier gas and non carrier gas with variable bypass vaporizers:
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the gas delivered to the variable bypass vaporizer is divided into carrier gas, which flows over liquid anesthetic in the vaporizing chamber, and noncarrier gas, which leaves the vaporizer unchanged.
because the gas flowing into the modern day vaporizer is divided into two streams, it is also known as the variable bypass vaporizer. |
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Where should variable bypass vaporizers be located?
why? |
they should be located outside the circle system, between the flowmeters in common gas outlet.
this placement lessens the likelihood of concentration surges during the use of the oxygen flush valve. |
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What risk is associated with dysfunctional flush valve?
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a damaged or defective flush valve can stick in the fully open position, causing barotrauma.
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What is the temperature and pressure in the desflurane vaporizer?
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39°C and 1500 mmHg.
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Is the desflurane vaporizer flow over vaporizer?
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no, the desflurane vaporizer is not the flow over vaporizer.
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Which modern gas vaporizer is not a variable bypass vaporizer?
What kind is it? |
Tec 6.
it is a dual gas blender vaporizer. |
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What are the concerns with the tec 6 vaporizer when a change in altitude is encountered?
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at higher altitudes, the partial pressure of desflurane will be decreased in proportion to the atmospheric pressure.
because the tec 6 vaporizer is a dual gas blunder, it will maintain a constant concentration of vapor output, not a constant partial pressure regardless of ambient pressure. a manual adjustment of the concentration control dial is required. |
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What is the source of heat in the tec 6 desflurane vaporizer?
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the gas is electrically heated in the sump that is upstream of both the common outlet and shut off valve.
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Does fresh gas flow go through the desflurane liquid in the vaporizer?
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no.
desflurane is heated to 39°C which creates saturated vapor pressure of 2 atmospheres. This drives the agent toward the fresh gas flow. fresh gas flow never comes in contact with the liquid in a desflurane vaporizer. |
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Give two reasons why desflurane needs a specially designed vaporizer:
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desflurane vapor pressure is 669 mmHg which is near atmosphere pressure, so it almost boils at sea level.
desflurane is only 1/5 as potent as other volatile anesthetics, so a relatively large volume of vapor must be delivered to the patient. |
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Why is it that you cannot use desflurane in the variable bypass vaporizer?
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the cooling effect associated with large quantities of desflurane is great.
a variable bypass vaporizer could not maintained constant temperature if desflurane were delivered from one of them. also, because desflurane vaporizers so extensively, a tremendously high fresh gas flow will be necessary to dilute the desflurane to clinically appropriate concentration. the heated tec 6 vaporizer overcomes these delivery problems. |
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Does the tec 6 vaporizer automatically compensate for changes in elevation?
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no.
the concentration of desflurane is not affected, but the partial pressure decreases at higher elevations. to compensate for this, we must deliver more anesthetic on the percent control dial. |
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Calculate the partial pressure of desflurane delivered from the tec 6 vaporizer at sea level (760 mmHg) and also in the mountains (600 mmHg).
dose: 5% |
0.05 x 760 equals 38 mmHg.
0.05 x 600 equals 30mmhg. 5% in the mountains is lighter anesthesia. |
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What would happen to desflurane if there were used in the flow over vaporizer at high altitude?
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because it has high vapor pressure (669 mmHg) at 20°C, it would boil at room temperature at high altitude if not used in a specially constructed, heated, and pressurized vaporizer.
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You are scheduled to provide anesthesia to a patient with known susceptibility to malignant hyperthermia.
how will you prepare the gas machine in anticipation of this case? |
the concern is presence of trace amounts of volatile agent in the rubber and plastic components of the machine, ventilator, and CO2 absorber. The following three things need to be done:
the machine should be thoroughly flushed with 100% oxygen for at least 10 minutes to remove residual traces of agent from rubber and plastic components of the machine. the breathing circuit and CO2 canister should be replaced. vaporizers should be drained, inactivated, or removed. |
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What are the American Society for testing and materials standards for reservoir bag's?
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they require the bag be able to distend up to four times its normal capacity with pressure not exceeding 50 cm of water.
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List five components of the circle system:
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gas reservoir bag.
two corrugated tubes. two unidirectional valves. a canister containing CO2 absorbent. an overflow valve to permit the escape of excess gas. |
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Describe five characteristics of the circle system:
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is the most common semiclosed anesthesia breathing system.
it is a true breathing circuit. anesthetic gases and oxygen circulate in one direction entirely within the confines of the components of the system. inspired concentrations change slowly as the fresh gas flow is increased. inspired oxygen concentrations cannot be predicted when using low flows below 1.2 L. |
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Name five advantages of the circle system:
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conservation of gas.
conservation of body heat. conservation of moisture. minimal operating room pollution. relative consistency of inspired concentration. |
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What is the major advantage of using a pediatric circle absorber system while anesthetizing a child?
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it conserves body heat and moisture.
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Name five disadvantages of the circle system:
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possible tubing disconnection.
possibility of leaks. exhaustion of soda lime and the CO2 absorber. failure of unidirectional valves. it is not easily movable. |
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What is the purpose of the unidirectional valves and the circle system?
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to prevent rebreathing of exhaled gases.
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Where does the fresh gas flow enter the breathing circuit in the circle system?
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it enters the circuit between the absorber and inspiratory valve.
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Which circle system component generates the greatest resistance to breathing during spontaneous respiration?
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the valves.
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What inspiratory effort is required to open most unidirectional valves?
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0.5 to 1 cm of water.
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In a circle system, where is the dead space located?
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between the y piece and the patient.
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Why is rebreathing not a reasonable option with a semi
open system ? |
because the semi open system requires very high flow of fresh gas.
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What are the two major features of the semi open anesthetic breathing system?
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gas reservoir bag.
utilization of unidirectional valves and or high fresh gas flow rates to prevent rebreathing of exhaled gases. |
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What are the four advantages of the semi open system?
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light weight.
portable. easy to clean. low resistance to gas flow. |
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What are the two main features of the semi closed anesthetic breathing system?
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it has a gas reservoir bag.
it provides partial rebreathing of exhaled gases. |
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Why is the APL valve important in semiclosed system?
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because it automatically release pressure within the semiclosed system.
it adjusts the limit of positive pressure attained within the circuit and alters the amount of gas contained within the rebreathing bag. when the desired pressure in the circuit is exceeded, gas flows out of the APL valve and is vented into the scavenging system. |
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When does a semiclosed or semi open system exist with a circle system?
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when high fresh gas flows are used with a circle system.
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When does a closed system exist?
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when the fresh gas flow to the circle system provides oxygen equal to that being consumed by the patient, 150 to 500 mL per minute of oxygen.
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What oxygen flow rate should be used when using a closed system?
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150 to 500 mL per minute. This satisfies the patients oxygen requirements during anesthesia.
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What is the minimum oxygen gas flow for a 70 kg man breathing in a closed system?
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150 mL per minute.
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What is the major feature of the closed anesthetic breathing system?
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the fresh gas in flow into a circle system is decreased sufficiently to permit closure of the overflow valve, and all the exhaled CO2 is neutralized in the CO2 absorber.
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What are the four advantages of a closed system?
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maximum humidification.
efficiency of gas usage. less pollution of gases into the atmosphere. economy. |
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What is the major disadvantage of a closed breathing system?
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inability to rapidly change the delivered concentrations of anesthetic gases and oxygen.
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What two things should be appreciated when switching from a closed to a semiopen system?
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the low flow rate needs to be changed to a high flow rate.
there will no longer be rebreathing of exhaled gases or chemical neutralization of carbon dioxide. |
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What are the two main features of the open anesthetic breathing system?
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there is no gas reservoir bag and no rebreathing of exhaled gases.
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What are the two disadvantages of the open anesthetic breathing system?
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the absence of a physical connection of this anesthetic breathing system to the patient results in spillage of anesthetic gases into the atmosphere and an inability to assist or control ventilation of the lungs.
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Which breathing circuit, open or closed, have the slowest induction time?
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closed.
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Greatest heat loss occurs with which type of breathing system?
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open or non rebreathing.
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Which breathing system have no valves?
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open systems, open open drop systems.
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Identify the major advantages of the ayres t piece:
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it can supply varying concentrations of inspired oxygen without positive pressure when the patient is breathing spontaneously.
CO2 accumulation is minimized and resistance to ventilation is minimal since there are no reservoir bag's or valves. |
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What flow rate must be achieved when using the ayres t piece to prevent rebreathing or air entrapment?
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2 to 3 times the patient's minute ventilation.
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What is the modification of the mapelson D system also called?
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Bain circuit.
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Why are soda lime granules a certain size?
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the size provides an appropriate balance between absorption efficiency surface area and resistance to airflow (channeling).
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What is channeling?
what causes channel? |
channeling is the preferential passage of gases through the soda lime canister through low resistance pathways.
loose packing of absorbent granules. |
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What problem will develop if there is channeling through a CO2 absorber?
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rebreathing of CO2.
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What is the recommended mesh size for soda granules?
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4 to 8.
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Is the recommended size of soda granules represents a compromise between what two factors?
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absorption capacity in resistance to airflow.
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|
What is the advantage and disadvantage of small soda lime granules?
|
there is increased absorption capacity because there is larger surface area, but there is also increased resistance to airflow because there are smaller interspaces.
Small = tightly packed = harder to breathe through. |
|
|
What happens to the circle system if the plastic packing wrapper is inadvertently left on the CO2 absorption canister?
|
a total obstruction of the circle system.
|
|
|
When the soda lime becomes exhausted, what is seen in how is the problem corrected?
|
it changes to violet color.
at this time, high fresh gas flows are used to blow CO2 out of the system, and the canister to be changed after the case. |
|
|
The soda lime canister turns blue during the case and it is not possible to change it. What should be done to compensate for this?
|
increase fresh gas flow rate.
|
|
|
List three indicators for exhaustion of soda lime:
|
absorber turns color.
inspired CO2 concentration increases (because of rebreathing). the patient shows signs of CO2 retention including flushed dry skin, tachycardia, dysrhythmias, and hypertension. |
|
|
List four initial signs and symptoms exhibited by the patient when soda lime becomes exhausted:
|
increased blood pressure.
increased pulse. dry flushed skin. cardiac dysrhythmias. |
|
|
When filled, what percent of the space in a soda lime canister is air?
|
about 50%.
|
|
|
How many liters of CO2 can be absorbed for each 100 g of soda lime?
|
26 L per 100 g.
|
|
|
What are the five final products when CO2 reacts with soda lime?
|
calcium carbonate.
sodium hydroxide. potassium hydroxide. water. heat. |
|
|
What are the four final products when CO2 reacts with baralyme?
|
calcium carbonate.
barium hydroxide. water. heat. |
|
|
What is the most abundant constituent in soda lime and baralyme?
|
calcium hydroxide. As high as 80% in baralyme.
|
|
|
What is the general name for the type of chemical reactions occurring in the CO2 absorber?
what is happening ? |
neutralization.
an acid is neutralized by a base. |
|
|
What are the three characteristics high frequency jet ventilaton?
|
small tidal volume that is less than dead space.
high ventilation rate of 30 to 3000 breaths per minute. low airway pressure. |
|
|
What is the mechanism of operation of high frequency jet ventilation?
|
there is bias flow of fresh gas at the level of the oscillator which provides the source of respiratory gas and washes out CO2.
induction of high velocity pulse of gas into the airway through a narrow cannula entrains fresh gas. |
|
|
What principle of physics applies to the jet ventilator?
|
the Venturi effect and the bernoulli principle.
|
|
|
How is trans tracheal ventilation performed?
|
by inserting a large catheter through the cricothyroid membrane and connecting it to a source of oxygen under pressure.
|
|
|
what two criteria must be met when providing an oxygen or gas source for trans tracheal jet ventilation?
|
high pressure oxygen source.
regulating valve. |
|
|
What 3 places can we get high pressure oxygen for jet ventilation?
|
central wall outlets.
hi flow tank regulators, 50 to 100 PSI. the flush valve on the anesthesia machine. |
|
|
Can you use a low pressure self inflating resuscitation bag for jet ventilation?
|
it does not provide enough flow, but you can use it temporarily until a more definitive airway is secure.
|
|
|
Describe the three systems that work reliably and can be easily and inexpensively assembled for trans tracheal jet ventilation:
|
a jet injector blow gun powered by pipeline oxygen pressure.
a jet injector powered by oxygen cylinder regulator. the anesthesia machine flush valve. |
|
|
What are the five complications of high frequency jet ventilation?
|
gas trapping.
bronchoconstriction. failure to adequately ventilate the patient. inaccurate delivery of anesthetic gases. damage to tracheal mucosa and thickened secretions because of inadequate humidification. |
|
|
What is the most common complication to a patient being jet ventilated?
|
tracheal mucosa damage and thickened secretions blocking the airway.
|
|
|
What effect does the high frequency jet ventilation have on the risk of barotrauma?
|
it increases the risk.
|
|
|
List five complications of high frequency trans laryngeal jet ventilation:
|
barotrauma by pneumothorax or mediastinum air.
gastric dilation. inadequate ventilation during inhalation or exhalation. vocal cord motion (not with trans tracheal jet ventilation). blowing tumor, blood, or debris into the depths of the lungs. |
|
|
List seven complications of trans tracheal jet ventilation:
|
barotrauma with pneumothorax.
sub cutaneous emphysema. mediastinum emphysema. difficulty with exhalation. arterial perforation. esophageal puncture with bleeding. damage to tracheal mucosa if non humidified gas is used. |
|
|
What sign is the hallmark of Laryngotracheal damage?
|
stridor.
|
|
|
Is recurrent laryngeal nerve injury a common complication of high frequency trans laryngeal or trans tracheal jet ventilation?
|
no.
|
|
|
Does the descending bellows descend during the inspiratory phase or the expiratory phase?
|
the descending bellows (hanging bellows) descends during the expiratory phase.
|
|
|
Why is the descending bellows a potential disadvantage if a disconnect occurs?
|
if there is a disconnect, the descending bellows will continue its upward and downward movement.
the drive gas pushes the bellows upward during the inspiratory phase and room air is in trained into the breathing system at the site of disconnect because gravity acts on the weighted bellows. |
|
|
Which bellows is safer when there is a disconnect, the ascending bellows or the descending bellows?
|
the ascending bellows is safer.
this is because the ascending bellows will not rise if disconnection occurs. Also, the ascending bellows permits easier detection of circuit leaks or disconnects and less chance of high airway pressures from gas entering the breathing circuit through bellows leaks. |
|
|
Why does looking at the volume return on an a sending bellows not reflect true title volume?
|
the respirometer measures exhaled gases. Title volume settings of the ascending bellows, as indicated on the outside of the plastic container, are different from respirometer readings. This is because of compression of gases, expansion of the breathing circuit closes during mechanical inspiration and the addition of humidifiers.
decreased lung compliance will also force gases that were not used by the patient through the respirometer. |
|
|
The gas that enters the bellows during expiration is what?
|
exhaled gases from the patient.
|
|
|
What gas is present outside the bellows ?
|
pressurized oxygen from the ventilator power outlet. It is found between the inside wall of the enclosure and the outside wall of the bellows.
|
|
|
What gases are present within the bellows?
|
all anesthetic gases.
the inside of the bellows is an extension of anesthesia breathing circuit. this is true for both a sending and descending bellows. |
|
|
Cycling of of pressure limited ventilator is triggered by what?
|
inspiratory phase terminates when a preselected pressure is achieved in the ventilator circuit. When this pressure is reached, the ventilator cycles.
|
|
|
Describe the effect of intermittent positive pressure ventilation on the pulmonary circulation:
|
it causes compression of the pulmonary capillaries with the shift of blood from capillaries to pulmonary arteries and veins.
|
|
|
Patient has been on mechanical ventilatory support for two days. You now want to withdraw mechanical support from the patient. List seven objective criteria supporting the feasibility of discontinuing mechanical ventilation:
|
vital capacity greater than 15 mL per kilogram.
AaDO2 less than 350 mmHg while breathing 100% oxygen. PO2 greater than 60 while breathing 50% oxygen. maximal negative inspiratory pressure is more than 20 cm of water. normal pH. spontaneous respiratory rate less than 20. Vd/Vt less than 0.6. |
|
|
What is the suggested protocol to wean patient from SIMV?
|
progressively decrease the number of breaths by 1 to 2 breaths per minute as long as the P. CO2 and respiratory rate remained acceptable.
|
|
|
After weaning and removal from mechanical ventilation, you are ready to remove the tube. What two criteria indicate awake extirpation is appropriate?
|
tolerates two hours of spontaneous breathing on the tee piece.
when patient tolerates SIMV of one to two breaths per minute without deterioration of blood gas, mental status, or cardiac function. |
|
|
What is the effect of intermittent positive pressure ventilation on cardiac output, blood pressure, and venous return?
|
it decreases cardiac output, arterial blood pressure, and venous return.
|
|
|
Explain how intermittent positive pressure ventilation may increase heart rate?
|
reflex from decrease in blood pressure.
|
|
|
Describe intermittent mandatory ventilation:
|
intermittent mechanical inflation of the lungs during periods of spontaneous ventilation.
|
|
|
When do we use intermittent mandatory ventilation?
|
during weaning.
the weaning is initiated by gradually decreasing the number of mechanical breaths delivered each minute. |
|
|
Compare intermittent mandatory ventilation with assist control ventilation:
|
assist control is set for a fixed rate, and initiation will trigger a set tidal volume.
intermittent mandatory ventilation allows spontaneous respirations on their own while the patient is on the ventilator. |
|
|
What is the goal of humidifying inspired gas?
|
to improve the mobilization of secretions by increasing water content and decreasing viscosity.
|
|
|
When is ethylene oxide indicated?
|
for objects requiring sterilization that cannot be heated in a steam autoclave.
|
|
|
What three forms of sterilization kill all viruses and all spores?
|
steam autoclave.
ethylene oxide. reading. |
|
|
What are the trade names for glutaraldehyde?
|
cidex and cetylicide.
|
|
|
What does glutaraldehyde kill?
|
all microorganisms, including bacteria, viruses, and spores.
|
|
|
How should nondisposable equipment be sterilized after use on a patient with tuberculosis?
|
glutaraldehyde.
glutaraldehyde kills bacteria, viruses, and spores. |
|
|
What type of bacteria is most resistant to destruction?
|
acid fast bacteria, including tuberculosis.
|
|
|
What is the chemical name for household bleach?
|
sodium hypochlorite.
|
|
|
What solutions kills viruses?
|
sodium hypochlorite and glutaraldehyde.
|
|
|
Of the following, what is not killed by alcohol:
bacteria, viruses, spores, fungus? |
spores.
|
|
|
On what items do we use pasteurization ?
|
plastic and rubber anesthesia equipment.
|
|
|
Items that are disinfected with pasteurization are placed in water at what temperature, and for how long?
|
77°C (170°F) for 30 minutes.
|
|
|
Pasteurization kills what organisms?
|
bacteria.
|
|
|
Does the boiling at 100°C kill all organisms?
|
no.
it kills all bacteria, most spores, and most viruses. |
|
|
Alcohol used for disinfection will not kill what agents ?
|
spores and some viruses.
|
|
|
How can you clean laryngoscope blade?
|
steam autoclave.
ethylene oxide. liquid agents such as alcohol, glutaraldehyde are most frequently used. |
|
|
Of the following options, which would be inadequate for disinfecting laryngoscope blade: steam sterilization, gas sterilization, glutaraldehyde, or Betadine?
|
Betadine. Betadine is an antiseptic, and antiseptics are not suitable for disinfecting medical instruments or environmental surfaces.
|
|
|
What is einthovin's triangle?
|
a representation of the placement of three standard limb leads.
|
|
|
Where are the leads place for leads 1,2, and 3?
|
1: left arm positive, right arm negative, left leg ground.
2: right arm negative, left leg positive, left arm ground. 3: left arm negative, left leg positive, right arm ground. |
|
|
Where are the leads placed for v5?
|
the positive electrode for v5 is placed between the mid clavicular line and the fifth intercostal space.
the negative electrode is placed on the left or right arm. |
|
|
What two monitors detect cardiac dysrhythmias?
|
stethoscope.
electrocardiogram. |
|
|
Give five reasons for using electrocardiogram:
|
detect dysrhythmias (lead 1 or 2).
detect ischemia. detect electrolyte abnormalities. calculate heart rate. detect pacemaker malfunction. |
|
|
What is the size of the smallest square on EKG paper?
what does it represent? |
1 mm x 1 mm.
it represents 0.04 seconds. |
|
|
With the 12 lead EKG, where do we place v1?
|
over the fourth intercostal space on the right sternum, over the right atrium and right ventricle.
|
|
|
What is indicated by PR greater than .21?
|
first degree heart block.
|
|
|
Which lead best detects left ventricular myocardial ischemia?
why? |
v5.
this lead assesses the bulk of the left ventricle. |
|
|
Which leads best detects ischemia resulting from occlusion of the right coronary artery?
|
2,3, avf.
|
|
|
Which EKG leads best detect ischemia resulting from occlusion of the left circumflex?
what part of the heart muscle is supplied by the left circumflex? |
1, avl, v5 thru v6.
this is the lateral myocardium. |
|
|
The modified v5 lead monitors ischemia in what regions of the heart?
|
lateral and anterior walls.
|
|
|
How do you get the modified v5 lead?
|
by placing a left arm lead at the v5 position and selecting lead 1 on the monitor.
|
|
|
What EKG leads best detect ischemia resulting from occlusion of the left coronary artery?
what part of the myocardium is supplied the left coronary artery? |
1,avl,v1 thru v4.
the anterior myocardium is supplied by the left coronary artery. |
|
|
What EKG leads best detect ischemia resulting from occlusion of the left anterior descending?
|
v1 thru v4.
|
|
|
What part of the myocardium is supplied by the left anterior descending?
|
anteroseptal.
|
|
|
What is the characteristic EKG change with digitalis effect?
|
down sloping of the ST segment.
|
|
|
What should be done if sinus dysrhythmia develops?
|
watch closely.
|
|
|
Which is the best standard limb lead for detecting dysrhythmias?
why? |
lead two because it displays large P waves.
|
|
|
What are three characteristics EKG changes with high potassium?
|
prolongation of pr interval.
widening of qrs. Peaked or tented t waves. |
|
|
What electrolyte abnormality could be indicated by the appearance of peaked t waves on the EKG?
|
high potassium.
|
|
|
In a patient with low potassium, what change in heart rate may we see?
|
increase.
this is because there is increased automaticity of the atria and ventricles, reflecting a more rapid rate of spontaneous phase four depolarization. |
|
|
What are the four characteristic EKG changes with low potassium:
|
prolongation of pr.
prolongation of qt. flattening of t wave. appearance of prominent u waves. |
|
|
When do we see u waves on the EKG?
|
when there is low potassium.
it is not well understood why this happens. |
|
|
A deficiency of what electrolyte causes broad flattened t waves ?
|
potassium.
|
|
|
What are three characteristics changes on the EKG with high potassium?
|
shortening of qt interval.
slight prolongation of qrs. widening of t wave. |
|
|
Your patient has a wide QRS and a short qt. What electrolyte abnormality do you suspect?
|
high potassium.
|
|
|
What are the three characteristic EKG changes seen with low calcium?
|
prolonged qt.
increased st segment duration. flat or inverted t waves. |
|
|
What is chvostec's sign?
|
prolonged QT interval, increased ST segment duration, and flat or inverted T waves.
this is indicative of low calcium. |
|
|
How are premature atrial beats distinguished from premature ventricular beats?
|
they are generally not followed by a compensatory pause, unlike premature ventricular beats.
|
|
|
Hypertrophy of the left ventricle causes the QRS complex to be exaggerated in both height and depth, especially in what leads?
|
v1 and v6.
high r wave in these leads. |
|
|
What does a diphasic p wave indicate?
|
atrial hypertrophy, particularly of the left atrium.
|
|
|
Name two causes of ST segment depression:
|
sub endocardial ischemia or sub endocardial infarction.
also, don't forget that digitalis may cause down sloping of the ST segment. |
|
|
What are the two causes of ST segment elevation?
|
transmural ischemia (prinzmetal's angina) or transmural infarction.
|
|
|
List six indications for central venous catheter:
|
measure central venous pressure.
rapid infusion of fluids. pacemaker insertion. parenteral nutrition. chemotherapy. to remove air if there is high risk for venous air embolism. |
|
|
Which jugular vein, the right or the left, is preferred for CVP?
why? |
the right internal jugular.
this is because it has a straight course to the superior vena cava, where the left in internal jugular vein as the thoracic duct. |
|
|
What are the three risks of using the left internal jugular vein for central line insertion?
|
increased risk of:
vascular erosion. pleural effusion. puncture of the thoracic duct, leading to cyclothorax. |
|
|
Where should the tip of the central venous catheter be located ?
|
just above the junction of the superior vena cava and the right atrium.
|
|
|
When the central venous catheter is inserted via the right internal jugular, the tip of the catheter on x ray will be seen at what level of thoracic vertebrae?
|
below the inferior border of the clavicles and above the T4 T5 interspace, above the level of the 3rd rib.
|
|
|
Why should the transducer be positioned exactly for measurement of central venous pressure?
|
so that low pressure is can be measured accurately and reproducibly.
|
|
|
What causes the a wave on the CVP waveform?
|
right atrial contraction.
|
|
|
What causes the c wave on the CVP waveform?
|
a slight elevation of the tricuspid valve into the right atrium during ventricular contraction.
|
|
|
What causes the v Wave on the CVP waveform ?
|
blood flow into the right atrium before the tricuspid valve opens.
|
|
|
On the CVP waveform, what does the x dissent indicate?
|
it occurs during ventricular sisterly and represents atrial relaxation with downward displacement of the tricuspid valve.
|
|
|
On the CVP waveform, what does the y dissent indicate?
|
it occurs during nastily and represents early ventricular filling through the open tricuspid valve.
|
|
|
What is normal central venous pressure?
|
0 to 11.
|
|
|
Name four early signs of increased CVP:
|
distended peripheral veins.
increased right heart filling pressures. increased heart rate. bounding peripheral pulses. |
|
|
Name three pathological conditions that may occur with elevated central venous pressure:
|
pulmonary hypertension.
right heart failure. left heart failure. |
|
|
What two situations would cause the CVP reading to be higher than the wedge?
|
right ventricular failure with pulmonary hypertension.
pulmonary embolus. |
|
|
What is the most common complication of CVP?
|
infection.
|
|
|
What is the incidence of pneumothorax with subclavian CVP insertion?
|
1%.
|
|
|
What confirms the entry of the catheter into the internal jugular vein with CVP insertion?
|
the return of desaturated venous blood.
|
|
|
What five sites are acceptable for insertion of PA catheter, in order of ease of insertion?
|
right internal jugular.
external jugular. femoral. subclavian. basilar. |
|
|
What site should not be used for insertion of a PA catheter?
|
left internal jugular.
|
|
|
With right internal jugular insertion of the PA catheter, what is the distance to the right atrium?
|
18 to 22 cm.
|
|
|
With right internal jugular PA catheter insertion, what is the distance to the right ventricle?
|
28 to 32 cm.
|
|
|
With right internal jugular PA catheter insertion, what is the distance to the pulmonary artery?
|
40 to 50 cm.
|
|
|
With right internal jugular PA catheter insertion, what is the distance to pulmonary wedge?
|
45 to 50 cm.
|
|
|
With right internal jugular PA catheter insertion, what is the pressure in the right atrium?
|
6 to 8 mmHg.
|
|
|
With right internal jugular PA catheter insertion, what is the pressure in the right ventricle?
|
25/0.
|
|
|
With right internal jugular PA catheter insertion, what is the pressure in the pulmonary artery?
|
25/12.
|
|
|
With PA catheter insertion, what is the pressure with pulmonary wedge?
|
2 to 12.
|
|
|
Specify six indications for pulmonary artery catheter:
|
known cardiovascular disease.
where cross clamping of the thoracic aorta is anticipated. respiratory failure. suspected were diagnosed pulmonary embolus. previous cardiac surgery. when pneumonectomy is anticipated. |
|
|
List six additional indications for PA catheter insertion:
|
when fluid shift is anticipated.
sepsis. receiving continuous inatropes or vasodilators. pulmonary hypertension. cor pulmonale. treatment with bleomycin. |
|
|
What ejection fraction and cardiac index are suggestive of poor left ventricular function indicating the need for PA monitoring?
|
ejection fraction less than 40%.
cardiac index less than 2.1. |
|
|
What is the most severe complication of pulmonary artery monitoring?
|
artery perforation and hemorrhage.
|
|
|
What three actions should be taken to treat pulmonary artery perforation and hemorrhage?
|
replace volume.
add peep. isolate involved lung with double lumen tube into the non bleeding lung. |
|
|
What is the most common complication with the insertion of PA catheter?
|
arrhythmia as a catheter goes into the right ventricle.
|
|
|
What drug is used to treat arrhythmias that occur during placement of a PA catheter?
|
lidocaine.
|
|
|
What is the balloon capacity for number five PA catheter?
|
1.5 mL.
|
|
|
What is the most commonly used size of PA catheter?
|
seven French.
|
|
|
What are two causes of PA catheter not reaching the pulmonary artery?
|
perforation.
coiling. |
|
|
What is the range of normal pulmonary artery systolic and diastolic pressure?
|
15 to 30.
4 to 12. |
|
|
Your pulmonary catheter is properly wedged and a large v wave appears.
what is the cause? |
most likely mitral regurgitation.
|
|
|
What three measures are taken to increase the accuracy and precision of cardiac outputs measured by thermal dilution?
|
triplicate determinations are averaged with a delay of 60 to 90 seconds in between.
perform the measurement at end expiration (this reduces variability.) ensure that the rate of injection in volume of injecting are constant. |
|
|
What interferes with cardiac output determinations using thermal dilution method?
|
electric cautery. Do not perform cardiac output measurements during electric cautery.
|
|
|
Is the area under the thermal dilution curve directly related to or inversely related to cardiac output?
|
cardiac output is inversely proportional to the area under the thermal dilution curve.
|
|
|
If the area under the patient's thermal dilution curve is getting smaller, is the patient's cardiac output increasing or decreasing?
|
the smaller the area under the curve, a greater cardiac output.
|
|
|
If cardiac output injecting volume is too small, how will this affect measurement?
|
there will be a false high measurement.
|
|
|
If cardiac output injecting volume is too large, how will this affect the measurement?
|
there will be a false low.
|
|
|
Discuss the cardiac output curve (temperature time curve) and injecting volume that is too high or too low:
|
cardiac output is inversely proportional to the area under the temperature time curve.
the area under the curve will leak larger if greater volume is injected, so cardiac output will be falsely low. the area under the curve will be smaller if a smaller volume is injected, so cardiac output will be falsely high. |
|
|
Insufficiency of either of what two valves may lead to a falsely high thermal dilution cardiac output reading?
|
either tricuspid or pulmonic insufficiency will lead to falsely high thermal dilution readings.
|
|
|
A patient with tricuspid regurgitation has a thermal dilution cardiac output reading of 5 L per minute. Is this accurate ?
explain: |
this reading is falsely high.
tricuspid regurgitation produces a falsely elevated reading. |
|
|
With thermal dilution cardiac output monitoring, you inject 10 mL of cold injectate when the cardiac output computer is set for 5 mL. How will this affect the cardiac output reading?
|
the reading will be lower than the true cardiac output.
|
|
|
What is the relationship of lvedv, paop, lvedp, and ladp?
|
in the absence of mitral stenosis or pulmonary hypertension, they are all equal, and equal preload.
|
|
|
How does wedge pressure reflect lvedp in the patient with mitral valve stenosis?
|
lvedp is directly related to wedge, assuming there is an open conduit from the catheter tip to left ventricle.
since stenosis of the mitral valve impedes the flow of blood into the left ventricle, lvedp will be lower than wedge. so, wedge overestimates lvedp in the patient with mitral valve stenosis. |
|
|
How does wedge reflect lvedp in the patient with mitral valve insufficiency?
|
wedge reflects lvedp accurately with mitral valve insufficiency.
This is because the conduit between the tip of the catheter and the left ventricle is open. |
|
|
Identify three situations where pulmonary capillary wedge pressure will be greater than left ventricular end diastolic pressure:
|
mitral stenosis.
elevated alveolar pressure. pulmonary venous obstruction. |
|
|
Wedge pressure will be less than left ventricular edp in patients who have what valve problem?
explain: |
wedge will underestimate lvedp in patients with aortic regurgitation.
blood flowing back into the left ventricle from the aorta during diastole closes the mitral valve before systole actually begins. true end diastolic pressure cannot be detected by the wedged pulmonary artery catheter because the mitral valve is closed. |
|
|
Does pulmonary artery diastolic pressure reflect left ventricular end diastolic pressure (left ventricular preload)?
|
yes.
it is often used as an alternative to measuring wedge. |
|
|
After giving 200 mL of intravenous fluid, pulmonary artery systolic/diastolic increases from 22/6 to 40/25.
is this normal or abnormal? |
it is abnormal.
a small increase would be normal, according to starlings law. the most likely explanation is decreased left ventricular compliance (diastolic dysfunction). with decreased left ventricular compliance, small increase in left ventricular volume will produce a large increase in lvedp. This increase is reflected by the increase in pulmonary artery pressure. another cause could be systolic dysfunction. |
|
|
What three valuable cardiovascular parameters are obtained from arterial line?
|
left ventricular volume.
left ventricular function. systemic vascular resistance. |
|
|
How will arterial line tracing change it air gets into the line?
|
the pattern gets dampened.
|
|
|
Where is the proper placement of the pressure transducer in a sitting position for arterial line?
|
at the base of the year.
|
|
|
What does the dicrotic notch come from?
|
closure of the aortic valve.
|
|
|
When does false elevation of arterial line monitoring occur?
|
decreased arterial compliance.
decreased transducer system frequency (ringing or overshoot) producing distortion of the waveform. |
|
|
How can you clean laryngoscope blade?
|
steam autoclave.
ethylene oxide. liquid agents such as alcohol, glutaraldehyde are most frequently used. |
|
|
Of the following options, which would be inadequate for disinfecting laryngoscope blade: steam sterilization, gas sterilization, glutaraldehyde, or Betadine?
|
Betadine. Betadine is an antiseptic, and antiseptics are not suitable for disinfecting medical instruments or environmental surfaces.
|
|
|
What is einthovin's triangle?
|
a representation of the placement of three standard limb leads.
|
|
|
Where are the leads place for leads 1,2, and 3?
|
1: left arm positive, right arm negative, left leg ground.
2: right arm negative, left leg positive, left arm ground. 3: left arm negative, left leg positive, right arm ground. |
|
|
Where are the leads placed for v5?
|
the positive electrode for v5 is placed between the mid clavicular line and the fifth intercostal space.
the negative electrode is placed on the left or right arm. |
|
|
What two monitors detect cardiac dysrhythmias?
|
stethoscope.
electrocardiogram. |
|
|
Give five reasons for using electrocardiogram:
|
detect dysrhythmias (lead 1 or 2).
detect ischemia. detect electrolyte abnormalities. calculate heart rate. detect pacemaker malfunction. |
|
|
What is the size of the smallest square on EKG paper?
what does it represent? |
1 mm x 1 mm.
it represents 0.04 seconds. |
|
|
With the 12 lead EKG, where do we place v1?
|
over the fourth intercostal space on the right sternum, over the duration of the right atrium and right ventricle.
|
|
|
What is the advantage over of five lead EKG over a three lead EKG?
|
three lead is limited in detecting ischemia.
the five lead EKG can also better distinguish between atrial and ventricular dysrhythmias. |
|
|
Name the leads monitored with three lead EKG:
|
one, two, three.
|
|
|
Name the leads monitor with five lead EKG:
|
one, two, three,avr, avl, avf, as well as 13 Cordele unipolar lead which is usually placed in the v5 position.
|
|
|
How many millivolts a generated on the skin by EKG signals?
|
1 mV, which is 1000 micro volts.
|
|
|
What is indicated by PR greater than .21?
|
first degree heart block.
|
|
|
Which lead best detects left ventricular myocardial ischemia?
why? |
v5.
this lead assesses the bulk of the left ventricle. |
|
|
Which leads best detects ischemia resulting from occlusion of the right coronary artery?
|
2,3, avf.
|
|
|
Which EKG leads best detect ischemia resulting from occlusion of the left circumflex?
what part of the heart muscle is supplied by the left circumflex? |
1, avl, v5 thru v6.
this is the lateral myocardium. |
|
|
The modified v5 lead to tax ischemia in what regions of the heart?
|
lateral and anterior walls.
|
|
|
How do you get the modified v5 lead?
|
by placing a left arm lead at the v5 position and selecting lead 1 on the monitor.
|
|
|
What EKG leads best detect ischemia resulting from occlusion of the left coronary artery?
what part of the myocardium is supplied the left coronary artery? |
1,avl,v1 thru v4.
the anterior myocardium is supplied by the left coronary artery. |
|
|
What EKG leads best detect ischemia resulting from occlusion of the left anterior descending?
|
v1 thru v4.
|
|
|
What part of the myocardium is supplied by the left anterior descending?
|
anteroseptal.
|
|
|
What is damping of transducers?
what causes damping? |
how quickly the system comes to rest after being set in motion.
air bubbles, thrombus formation, and kinking may damp the system. |
|
|
List six arterial cannulation sites, in order of preference:
|
radial.
ulnar. brachial. axillary. femoral. dorsal. |
|
|
Which site is the most common for arterial line?
|
radial.
|
|
|
Which type of catheters are preferred for radial arterial line?
|
non tapered catheters.
|
|
|
Why is the ulnar artery more difficult to insert a catheter into?
|
it is deeper and more torturous.
|
|
|
Which artery is the primary supply of blood flow to the hand?
|
the ulnar artery.
|
|
|
Where is the insertion site for the brachial artery?
|
medial to the biceps tendon.
|
|
|
What is the risk with brachial arterial line insertion?
|
median nerve damage.
|
|
|
Where is the insertion site for the axillary artery?
|
at the Junction of the pectoral and deltoid muscles.
|
|
|
What is the risk with axillary arterial line insertion ?
|
nerve damage from hematoma.
|
|
|
What is the advantage to femoral arterial line insertion during emergencies?
|
it provides easy access in low flow states.
|
|
|
Does the bourdon gauge measure high or low pressure?
|
it measures high cylinder pressures.
|
|
|
Does the bourdon gauge measure the relative or absolute pressure?
|
it measures pressure relative to the atmospheric pressure.
|
|
|
What is the name of the regulator that is found on cylinder tanks?
|
the bourdon gauge.
|
|
|
What do pressure reducing devices/regulators do?
|
they reduce the high and variable pressure and a cylinder to a lower pressure, about 40 to 48 psi. Gas flow is maintained constant without changing the supply pressure.
|
|
|
What do the second stage reducing devices/regulators do?
|
they receive gas from either the pipeline or the cylinder reducing device (regulator) and reduce the pressure further to 26 PSI for nitrous oxide and 14 psi for oxygen.
|
|
|
What is the purpose of second stage reducing device?
|
the purpose is to eliminate fluctuations in pressure so that flow remains constant.
|
|
|
Besides reducing line pressure, what other function does a second stage regulator provide?
|
in addition to reducing line pressure, the second stage regulator maintains constant flow with changing supply pressure.
in other words, the second stage regulator eliminates fluctuations in pressure. |
|
|
When the bourdon gauge reads zero, what is the pressure in the tank?
|
1 atmosphere.
|
|
|
Describe the function of the second stage regulator:
|
the second stage regulator receives oxygen from a cylinder or wall. The incoming oxygen pressure of 40 to 50 PSI is reduced by the second stage regulator to 10 PSI and then the oxygen is delivered to the flow control valve.
|
|
|
What is the purpose of cracking compressed gas cylinders?
|
the purpose of cracking a cylinder is to clear the soldiers of any dirt or dust before a fitting is placed.
when the cylinder is turned on, the gas enters the yoke and passes through a strainer nipple, which serves as a filter that removes dust particles that may be present on the cylinder valve or the contact surface of the yoke. |
|
|
Which two gases are in liquid form in pressurized cylinders?
|
nitrous oxide and CO2.
|
|
|
What is the working pressure of the hospital pipeline system?
|
50 PSI.
|
|
|
What are common contaminants of medical gas lines?
|
oil, water, bacteria, particulate matter, and residual sterilizing solutions.
|
|
|
Which contaminant of medical gas appliance is most common?
|
water.
|
|
|
How often should cylinders be inspected?
|
at least every five years, or, with a special permit, up to every 10 years.
|
|
|
What agency controls such processes as the filling and manufacturing of gas cylinders?
|
the United States Department of Transportation.
|
|
|
List the responsibilities of the Department of transportation when dealing with compressed gases:
|
the Department of Transportation has set requirements for the manufacturing, lacking, labeling, filling, qualification, transportation, storage, handling, maintenance, requalification and disposition of medical gas cylinders and containers.
|
|
|
Who regulates medical gas appeared he?
|
the United States pharmacopeia national formulary.
|
|
|
What is the role of the federal food and drug administration in the regulation of compressed gas cylinders?
|
they enforce regulation of the federal food, drug and cosmetic act. They inspect medical gas and notification plants every other year.
oxygen cylinders and nitrous oxide tanks have been recalled for numerous reasons including improper labeling, and appropriate testing, filling of cylinders with the wrong gases, and contamination of gases with ammonia, rusty water, oil, or chlorine. |
|
|
What is Woods metal?
|
it is an alloy commonly used, composed of varying percentages of bismuth, lead, tin, and cadmium. It is used as a safety relief device (fusable plug.)
it melts at the predetermined temperature to release gas from a cylinder in case the cylinder heats up. |
|
|
What is the pressure in a full E. cylinder of oxygen?
|
2200 PSI.
|
|
|
How many liters of oxygen can be released from a full E. cylinder?
|
625 to 700 L.
|
|
|
How long does it take to empty a fully cylinder of oxygen that is turned on at 5 L per minute?
|
slightly more than two hours.
|
|
|
A full E. cylinder at 800 PSI is connected to a delivery system set to provide 2 L per minute. How long will the E. cylinder supply provide this flow rate?
|
there is one third the original volume, or, 208 L of gas remaining. This will last 104 minutes.
|
|
|
With an E. cylinder, what do pressures of 2000, 1000, and 500 PSI correspond to?
|
2000 is full.
1000 is half full. 500 is the one quarter full. |
|
|
If the pressure on an E. cylinder of oxygen reads 700 PSI, how much gas remains in the cylinder?
|
210 L.
|
|
|
At what pressure should the oxygen each cylinder on an anesthesia machine be changed?
|
at least half full, about 1000 PSI.
|
|
|
For which gases can the amount remaining in the cylinder be determined by the reading on the pressure gauge?
|
oxygen, air, helium, and nitrogen.
this is because these gases are not in liquid form in high pressure cylinders. |
|
|
How many liters of nitrous oxide can be released from a full E. cylinder?
|
1590 L.
|
|
|
During the case, the wall oxygen pressure fails. The E. cylinder registers 2000 PSI, but within a few breaths, falls to zero pressure. What should you do?
|
open the valve on the E. cylinder. The gauge may read 2000 after the E. cylinder was turned off if the pressure and the line was not vented.
|
|
|
Why might the pressure in nitrous oxide tank fall when the tank is in use even if there is liquid in the tank?
|
pressure will fall slowly because the tank cools as nitrous oxide exits. Vapor pressure of nitrous oxide in the tank decreases as temperature falls even when there is liquid in the tank.
|
|
|
What is the situation when the pressure gauge on a tank of nitrous oxide begins to fall rapidly?
|
the tank has no more liquid nitrous oxide.
|
|
|
What pressure indicates that there is no liquid left in the nitrous oxide tank, and how full is the tank at this time?
|
745 PSI. The cylinder is less than one quarter full and there is no liquid remaining.
|
|
|
Nitrous oxide tank pressure gauge reads 700 PSI. What is the significance of this?
|
nitrous oxide pressure low 740 PSI indicates that the cylinder contains no liquid and is less than one quarter full and should be changed. Excellent what volume of nitrous oxide is left in the tank when the liquid is gone?
|
|
|
What prevents backflow pressure in the gas cylinders?
|
valve yokes.
|
|
|
Explain the purpose of the pin index system:
|
the pin index system ensures that the cylinders will be non interchangeable. For example, oxygen cannot be attached to nitrous oxide yoke.
|
|
|
What size gas cylinders have the pin index system?
|
size a (small) through sized E.
|
|
|
describe the diameter index safety system (DISS) and state its purpose:
|
the pipeline inlet fittings are gas specific diss threaded body fittings. This system provides threaded non interchangeable connections for medical gas lines. This minimizes the risk of mis connection.
|
|
|
What 11 components of the anesthesia machine are required?
|
gas inlet.
pressure regulators. oxygen pressure failure devices. flow control valves and flowmeters. vaporizers. fresh gas outlet. spirometer's. reading circuit pressure gauges. ventilators. waste gas scavengers. oxygen analyzers. |
|
|
What are the components of the low pressure system of the anesthesia machine?
|
flow indicators.
vaporizers. vaporizers circuit control valves. back pressure safety devices. low pressure safety devices. the common gas outlet. |
|
|
List the nine parameters that the anesthesia machine must monitor in order to comply with astm f 1850 00:
|
newly manufactured machines must have monitors that display: continuous breathing system pressure.
exhaled tidal volume. ventilatory carbon dioxide concentration. anesthetic vapor concentration. inspired oxygen concentration. arterial oxygen concentration. oxygen supply pressure. arterial blood pressure. continuous electrocardiogram. |
|
|
Describe the three functions of the interlock system on the anesthesia machine:
|
the vaporizer manifold holds 2 to 3 units. The interlock system, also known as the vaporizer exclusion system, prevents more than one vaporizer from being turned on at a time. You cannot deliver more than one agent simultaneously.
the interlock system also ensures that all vaporizers are locked in such that leaks are decreased and trace vapor output is minimal when the vaporizer is off. |
|
|
What gas machines generally have machine outlet check valves, drager or ohmeda?
|
ohmeda. Most of them have it.
|
|
|
Where is the machine outlet check valves located?
|
downstream from the vaporizers and upstream from the oxygen flush.
|
|
|
When is the machine outlet check valve open?
|
in the absence of back pressure.
|
|
|
When is the machine outlet check valve closed?
|
when back pressure is exerted on it, like with intermittent positive pressure and oxygen flushing.
|
|
|
What is the purpose of the check valve found at the cylinder inlet to the gas machine?
|
the single check valve between the machine and the cylinder prevent retrograde flow of gases from the machine to the atmosphere when there is no cylinder in the yoke.
|
|
|
List three functions of the anesthesia machine check valve:
|
prevents backflow from high pressure to low pressure sides (prevents pumping action of gases).
allows for an empty cylinder to be exchanged for a full one with minimal loss of gas. minimizes leakage from an open cylinder to the atmosphere. |
|
|
The check valve found between the cylinders that are double yoked as what purpose?
|
this check valve prevents transfer of gas from the cylinder with higher pressure to the cylinder with lower pressure. In addition, one of the double yolked cylinders can be changed while the other is in use.
|
|
|
Early vaporizer designs were susceptible to a pumping effect. Describe this pumping effect:
|
intermittent positive pressure in the circuit, like with ventilation or releasing the oxygen flush valve, caused fluctuating back pressure to be transmitted into the low pressure system. The result of this effect was an increased concentration of anesthetic delivery.
this happened more often with low flow rates. |
|
|
How is the pumping effect prevented in modern anesthetic vaporizers?
|
new anesthetic vaporizers incorporate mechanisms that decrease the size of the vaporizing chamber relative to the bypass channel and increase the volume of the inflow channel.
vapor saturated gas cannot make its way back into the bypass channel, and thus, the pumping effect is prevented. |
|
|
What system prevents filling a vaporizer with the incorrect agent?
|
the keyed filling ports system prevents this.
|
|
|
What is the transport "t" dial setting on the drager 20n gas machine?
|
it prevents tipping related problems.
|
|
|
What is the equivalent of the transport "T" dial setting on machines other than themdrager 20n?
|
the vaporizer cassette systems on other modern machines provide this function.
|
|
|
What type of anesthesia machines should be tested with a negative pressure leak test?
|
anesthesia machines with check valves should be tested with a negative pressure leak test.
|
|
|
Where and how is the negative pressure leak test performed on the anesthesia machine during checkout?
|
a suction bulb is attached to the common fresh gas outlet and then squeezed repeatedly until the bulb is fully collapsed. The anesthesia machine is leakfree if the bulb remains collapsed for at least 10 seconds.
|
|
|
Where is the valve for the scavenging system located?
|
in the breathing circuit or the ventilator. Either of these valves is connected to hoses leading to the scavenger system.
|
|
|
To what is the outlet of the scavenging system connected?
|
to the outside (with passive scavenging) or to a connection to the hospitals vacuum system (active scavenging).
|
|
|
What is the purpose of pressure relief valves?
|
negative and positive pressure relief valves protect the patient from the negative pressure of the vacuum system or the positive pressure from an obstruction in the disposable tubing.
|
|
|
What is the purpose of each of the two pressure relief valves of the scavenger system?
|
one is for positive pressure and one is for negative pressure.
|
|
|
When does the positive pressure relief valve of the scavenger system open?
|
if flow of waste gas into the vacuum source is insufficient and the reservoir bag distend.
the positive pressure relief valve will open in vent some of the exhaled gases into the room. |
|
|
When does the negative pressure relief valve of the scavenger system open?
|
when the flow of waste gas into the vacuum system is too high and the bag collapses. The negative valve opens and lets in room air.
|
|
|
What would happen if there was too much suction applied to the scavenging system?
|
the reservoir bag would collapse.
|
|
|
What would happen if there is too little suction applied to the scavenging system?
|
excessive pressure in the breathing system leading to barotrauma.
|
|
|
How frequently does the scavenging system need to be checked?
|
every day with your machine check.
|
|
|
Name the five components of the scavenging system:
|
the gas collecting system.
the transfer tubing. the scavenging interface. the gas disposal to bring. active or passive gas disposal assembly. |
|
|
What are indications that the scavenging system is malfunctioning?
|
increased positive pressure can be transferred to the breathing system resulting in decreased bellows movement from the ventilator.
increased ventilation pressures. desaturation due to decreased fresh gas flows and CO2 buildup. |
|
|
When the O2 flush button is pushed, what is the litre flow rate?
|
35 to 75 L per minute.
|
|
|
In the arrangements of flow meters, where is the oxygen flow meter best located?
|
it should be last in the sequence.
this is to ensure against accidental decrease in delivered oxygen concentration. last is the farthest to the right in the United States. |
|
|
Why do some modern gas machines have two flow meter tubes whereas other machines have one flow meter tube?
|
2 tubes allows you to titrate both high and low flow rates with the same flow meter.
single flow meter tubes has dual tapers in the tube, one for low flow and one for hi flow. |
|
|
What is the fail safe system design to do?
|
prevent delivery of hypoxic gas mixtures.
|
|
|
Does the fail safe system operates on the basis of pressure or flow?
|
is activated by low pressure.
|
|
|
When does the fail safe system shut off flow of all gases?
|
it shuts off or proportionally decreases flow of all gases when the pressure in the oxygen delivery line decreases to less than 20 to 30 psi.
|
|
|
At what pressure does the fail safe valve shut off the flow of nitrous oxide or other gases?
|
line pressures of 15 to 30 psi will usually close the flow of all gases, except oxygen, to the common gas outlet.
|
|
|
Which anesthetic gas has no fail safe valve?
|
oxygen.
|
|
|
During the case, the shuts down all non oxygen gas flow. What happened?
|
the oxygen pressure fell below 25 to 30 psi. When oxygen pressure falls below 25 to 30 psi (roughly 50% of normal) the faill safe valve automatically closes nitrous and other gas lines to prevent delivery of hypoxic mixtures of gases.
A gas whistle or electrical alarm sounds to alert the anesthetist to this occurrence. |
|
|
What do you do when the oxygen low pressure alarm sounds?
|
this means there is a profound loss of oxygen pipeline pressure.
fully open the E. cylinder, disconnect the pipeline, and consider the use of low gas flow. |
|
|
What type of flow meter uses rotameters?
|
variable orifice flow meters.
|
|
|
What is thorpe tube?
|
it is a tapered (variable orifice) tube with an indicator bobbin that is part of the constant pressure variable orifice flow meter found in anesthesia machines.
|
|
|
Describe the tapering of the thorpe tube and the location in the anesthesia machine:
|
the smallest diameter is at the bottom of the tube and the largest diameter is at the top.
it is located in the manifold area of the anesthesia machine. |
|
|
What is the purpose of a proportioning system?
|
proportioning systems have been placed on newer anesthesia machines to prevent delivery of hypoxic gas mixture. The delivery of nitrous oxide and oxygen are linked. The minimum concentration of oxygen that could ever leave the common gas outlet is 25%.
|
|
|
How does the proportioning system work?
|
nitrous oxide and oxygen are interfaced either mechanically or pneumatically so that the minimum oxygen concentration is 25%.
the proportioning system lowers the delivery of gases other than oxygen to keep the delivered oxygen concentration above 25%. |
|
|
When does the proportioning system alarm go off ?
|
the alarm will sound when the nitrous oxide/oxygen mixture falls below the low limit.
|
|
|
How often should a complete test of all the anesthesia apparatus be performed?
|
at least each day before the first case.
|
|
|
Give six examples of how of vaporizer can become hazardous:
|
incorrect anesthetic.
bypass chamber contaminated with liquid anesthetic if the vaporizer is tipped. simultaneous administration of two anesthetics if the interlock mechanism is not working. development of leaks. contaminated liquid anesthetic placed into the vaporizer. over filling of the vaporizer. |
|
|
If the vaporizer is calibrated at sea level, will the amount of anesthetic delivered at high altitude (Denver Colorado) the greater, the same, or less than the dial setting?
explain: |
the percent going to the patient is more than the dial setting in the situation.
consider the formula: vv=[(cf) x (vp)]/(bp minus vp) at high altitude, the barometric pressure is decreased so the denominator of the equation (bp minus vp) gets smaller. Because we are dividing by a smaller number, ratio increases to the volume vaporized is higher. this means that the percent going to the patient (i.e. volume vaporized divided by total flow times 100) is increased. |
|
|
A vaporizer is calibrated in Denver Colorado and set to deliver 1.5%, and a vaporizer is calibrated at sea level and set to deliver 1.5%. Will both patients the anesthetized to the same depth?
explain: |
the patient in Denver will not be as deep.
atmosphere pressure in Denver is 670 mmHg so the partial pressure of anesthetic going to the patient at 1.5% will be 10.5. atmosphere pressure at sea level is 760 mmHg, so the partial pressure of the anesthetic delivered at 1.5% will be 11.4 mmHg. |
|
|
The flow compensated vaporizer compensates for what?
how? |
temperature.
it is equipped with an automatic temperature compensating device that helps to maintain a constant vaporizer output flow over a wide range of temperatures. |
|
|
What volatile agents are delivered from variable bypass vaporizers?
|
isoflurane, enflurane, halothane, and sevoflurane.
|
|
|
Name three characteristics of modern day variable bypass vaporizers:
|
they are agent specific.
they are temperature compensated. carrier gas flows over the anesthetic liquid in the vaporizing chamber. |
|
|
Explain carrier gas and non carrier gas with variable bypass vaporizers:
|
the gas delivered to the variable bypass vaporizer is divided into carrier gas, which flows over liquid anesthetic in the vaporizing chamber, and noncarrier gas, which leaves the vaporizer unchanged.
because the gas flowing into the modern day vaporizer is divided into two streams, it is also known as the variable bypass vaporizer. |
|
|
Where should variable bypass vaporizers be located?
why? |
they should be located outside the circle system, between the flowmeters in common gas outlet.
this placement lessens the likelihood of concentration surges during the use of the oxygen flush valve. |
|
|
What risk is associated with dysfunctional flush valve?
|
a damaged or defective flush valve can stick in the fully open position, causing barotrauma.
|
|
|
What is the temperature and pressure in the desflurane vaporizer?
|
39°C and 1500 mmHg.
|
|
|
Is the desflurane vaporizer flow over vaporizer?
|
no, the desflurane vaporizer is not the flow over vaporizer.
|
|
|
Which modern gas vaporizer is not a variable bypass vaporizer?
|
Tec 6.
it is a dual gas blender vaporizer. |
|
|
What are the concerns with the tec 6 vaporizer when a change in altitude is encountered?
|
at higher altitudes, the partial pressure of desflurane will be decreased in proportion to the atmospheric pressure.
because the tec 6 vaporizer is a dual gas blunder, it will maintain a constant concentration of vapor output, not a constant partial pressure regardless of ambient pressure. a manual adjustment of the concentration control dial is required. |
|
|
What is the source of heat in the tec 6 desflurane vaporizer?
|
the gas is electrically heated in the sump that is upstream of both the common outlet and shut off valve.
|
|
|
Does fresh gas flow go through the desflurane liquid in the vaporizer?
|
no.
desflurane is heated to 39°C which creates saturated vapor pressure of 2 atmospheres. This drives the agent toward the fresh gas flow. fresh gas flow never comes in contact with the liquid in a desflurane vaporizer. |
|
|
Give two reasons why desflurane needs a specially designed vaporizer:
|
desflurane vapor pressure is 669 mmHg which is near atmosphere pressure, so it almost boils at sea level.
desflurane is only 1/5 as potent as other volatile anesthetics, so a relatively large volume of vapor must be delivered to the patient. |
|
|
Why is it that you cannot use desflurane in the variable bypass vaporizer?
|
the cooling effect associated with large quantities of desflurane is great.
a variable bypass vaporizer could not maintained constant temperature if desflurane were delivered from one of them. also, because desflurane vaporizers so extensively, a tremendously high fresh gas flow will be necessary to dilute the desflurane to clinically appropriate concentration. the heated tec 6 vaporizer overcomes these delivery problems. |
|
|
Does the tec 6 vaporizer automatically compensate for changes in elevation?
|
no.
the concentration of desflurane is not affected, but the partial pressure decreases at higher elevations. to compensate for this, we must deliver more anesthetic on the percent control dial. |
|
|
Calculate the partial pressure of desflurane delivered from the tec 6 vaporizer at sea level (760 mmHg) and also in the mountains (600 mmHg).
dose: 5% |
0.05 x 760 equals 38 mmHg.
0.05 x 600 equals 30mmhg. 5% in the mountains is lighter anesthesia. |
|
|
What would happen to desflurane if there were used in the flow over vaporizer at high altitude?
|
because it has high vapor pressure (669 mmHg) at 20°C, it would boil at room temperature at high altitude if not used in a specially constructed, heated, and pressurized vaporizer.
|
|
|
You are scheduled to provide anesthesia to a patient with known susceptibility to malignant hyperthermia.
how will you prepare the gas machine in anticipation of this case? |
the concern is presence of trace amounts of volatile agent in the rubber and plastic components of the machine, ventilator, and CO2 absorber. The following three things need to be done:
the machine should be thoroughly flushed with 100% oxygen for at least 10 minutes to remove residual traces of agent from rubber and plastic components of the machine. the breathing circuit and CO2 canister should be replaced. vaporizers should be drained, inactivated, or removed. |
|
|
What are the American Society for testing and materials standards for reservoir bag's?
|
they require the bag be able to distend up to four times its normal capacity with pressure not exceeding 50 cm of water.
|
|
|
List five components of the circle system:
|
gas reservoir bag.
two corrugated tubes. two unidirectional valves. a canister containing CO2 absorbent. an overflow valve to permit the escape of excess gas. |
|
|
Describe five characteristics of the circle system:
|
is the most common semiclosed anesthesia breathing system.
it is a true reading circuit. anesthetic gases and oxygen circulate in one direction entirely within the confines of the components of the system. inspired concentrations change slowly allows the fresh gas flow is increased. inspired oxygen concentrations cannot be predicted when using low flows below 1.2 L. |
|
|
Name five advantages of the circle system:
|
conservation of gas.
conservation of body heat. conservation of moisture. minimal operating room pollution. relative consistency of inspired concentration. |
|
|
What is the major advantage of using a pediatric circle absorber system while anesthetizing a child?
|
it conserves body heat and moisture.
|
|
|
Name five disadvantages of the circle system:
|
possible tubing disconnection.
possibility of leaks. exhaustion of soda lime and the CO2 absorber. failure of unidirectional valves. it is not easily movable. |
|
|
What is the purpose of the unidirectional valves and the circle system?
|
to prevent rebreathing of exhaled gases.
|
|
|
Where does the fresh gas flow enter the breathing circuit in the circle system?
|
it enters the circuit between the absorber and inspiratory valve.
|
|
|
Which circle system component generates the greatest resistance to breathing during spontaneous respiration?
|
the valves.
|
|
|
What inspiratory effort is required to open most unidirectional valves?
|
0.5 to 1 cm of water.
|
|
|
In a circle system, where is the dead space located?
|
between the y piece and the patient.
|
|
|
Why is rebreathing not a reasonable option with a semi
open system ? |
because the semi open system requires very high flow of fresh gas.
|
|
|
What are the two major features of the semi open anesthetic breathing system?
|
gas reservoir bag.
utilization of unidirectional valves and or high fresh gas flow rates to prevent rebreathing of exhaled gases. |
|
|
What are the four advantages of the semi open system?
|
light weight.
portable. easy to clean. low resistance to gas flow. |
|
|
What are the two main features of the semi closed anesthetic breathing system?
|
it has a gas reservoir bag.
it provides partial rebreathing of exhaled gases. |
|
|
Why is the APL valve important in semiclosed system?
|
because it automatically release pressure within the semiclosed system.
it adjusts the limit of positive pressure attained within the circuit and alters the amount of gas contained within the rebreathing bag. when the desired pressure in the circuit is exceeded, gas flows out of the APL valve and is vented into the scavenging system. |
|
|
When does a semiclosed or semi open system exist?
|
when high fresh gas flows are used with a circle system.
|
|
|
When does a closed system exist?
|
when the fresh gas flow to the circle system provides oxygen equal to that being consumed by the patient, 150 to 500 mL per minute of oxygen.
|
|
|
What oxygen flow rate should be used when using a closed system?
|
150 to 500 mL per minute. This satisfies the patients oxygen requirements during anesthesia.
|
|
|
What is the minimum oxygen gas flow for a 70 kg man breathing in a closed system?
|
150 mL per minute.
|
|
|
What is the major feature of the closed anesthetic breathing system?
|
the fresh gas in flow into a circle system is decreased sufficiently to permit closure of the overflow valve, and all the exhaled CO2 is neutralized in the CO2 absorber.
|
|
|
What other four advantages of a closed system?
|
maximum humidification.
efficiency of gas usage. less pollution of gases into the atmosphere. economy. |
|
|
What is the major disadvantage of a closed breathing system?
|
inability to rapidly change the delivered concentrations of anesthetic gases and oxygen.
|
|
|
What two things should be appreciated when switching from a closed to a semiopen system?
|
the low flow rate needs to be changed to a high flow rate.
there will no longer be rebreathing of exhaled gases or chemical neutralization of carbon dioxide. |
|
|
What are the two main features of the open anesthetic breathing system?
|
there is no gas reservoir bag and no rebreathing of exhaled gases.
|
|
|
What are the two disadvantages of the open anesthetic breathing system?
|
the absence of a physical connection of this anesthetic breathing system to the patient results in spillage of anesthetic gases into the atmosphere and an inability to assist or control ventilation of the lungs.
|
|
|
Which breathing circuit, open or closed, have the slowest induction time?
|
closed.
|
|
|
Greatest heat loss occurs with which type of breathing system?
|
open or non rebreathing.
|
|
|
Which breathing system have no valves?
|
open systems, open open drop systems.
|
|
|
Identify the major advantage is of the ayres t piece:
|
it can supply varying concentrations of inspired oxygen without positive pressure when the patient is breathing spontaneously.
CO2 accumulation is minimized and resistance to ventilation is minimal since there are no reservoir bag's or valves. |
|
|
What flow rate must be achieved when using the ayres t piece to prevent rebreathing or air entrapment?
|
2 to 3 times the patient's minute ventilation.
|
|
|
What is the modification of the mapelson D system also called?
|
Bain circuit.
|
|
|
Why are soda lime granules a certain size?
|
the size provides an appropriate balance between absorption efficiency surface area and resistance to airflow (channeling).
|
|
|
What is channeling?
what causes channel? |
channeling is the preferential passage of gases through the soda lime canister through low resistance pathways.
loose packing of absorbent granules. |
|
|
What problem will develop if there is channeling through a CO2 absorber?
|
rebreathing of CO2.
|
|
|
What is the recommended mesh size for soda granules?
|
4 to 8.
|
|
|
Is the recommended size of soda granules represents a compromise between what two factors?
|
absorption capacity in resistance to airflow.
|
|
|
What is the advantage and disadvantage of small soda lime granules?
|
there is increased absorption capacity because there is larger surface area, but there is also increased resistance to airflow because there are smaller interspaces.
|
|
|
What happens to the circle system if the plastic packing wrapper is inadvertently left on the CO2 absorption canister?
|
a total obstruction of the circle system.
|
|
|
When the soda lime becomes exhausted, what is seen in how is the problem corrected?
|
it changes to violet color.
at this time, high fresh gas flows are used to blow CO2 out of the system, and the canister to be changed after the case. |
|
|
The soda lime canister turns blue during the case and it is not possible to change it. What should be done to compensate for this?
|
increase fresh gas flow rate.
|
|
|
List three indicators for exhaustion of soda lime:
|
absorber turns color.
inspired CO2 concentration increases (because of rebreathing). the patient shows signs of CO2 retention including flushed dry skin, tachycardia, dysrhythmias, and hypertension. |
|
|
List four initial signs and symptoms exhibited by the patient when soda lime becomes exhausted:
|
increased blood pressure.
increased pulse. dry flushed skin. cardiac dysrhythmias. |
|
|
When filled, what percent of the space and a soda lime canister is air?
|
about 50%.
|
|
|
How many liters of CO2 can be absorbed for each 100 g of soda lime?
|
26 L per 100 g.
|
|
|
What are the five final products when CO2 reacts with soda lime?
|
calcium carbonate.
sodium hydroxide. potassium hydroxide. water. heat. |
|
|
What are the four final products when CO2 reacts with baralyme?
|
calcium carbonate.
barium hydroxide. water. heat. |
|
|
What is the most abundant constituent in soda lime and baralyme?
|
calcium hydroxide. As high as 80% in baralyme.
|
|
|
What is the general name for the type of chemical reactions occurring in the CO2 absorber?
what is happening ? |
neutralization.
an acid is neutralized by a base. |
|
|
What are the three characteristics of the high frequency jet ventilator?
|
small tidal volume that is less than dead space.
high ventilation rate of 30 to 3000 breaths per minute. low airway pressure. |
|
|
What is the mechanism of operation of high frequency jet ventilation?
|
there is bias flow of fresh gas at the level of the oscillator which provides the source of respiratory gas and washes out CO2.
induction of high velocity pulse of gas into the airway through a narrow cannula entrains fresh gas. |
|
|
What principle of physics applies to the jet ventilator?
|
the Venturi effect and the bernoulli principle.
|
|
|
How is trans tracheal ventilation performed?
|
by inserting a large catheter through the cricothyroid membrane and connecting it to a source of oxygen under pressure.
|
|
|
what two criteria must be met when providing an oxygen or gas source for trans tracheal jet ventilation?
|
high pressure oxygen source.
regulating valve. |
|
|
Where do we get high pressure oxygen for jet ventilation?
|
central wall outlets.
hi flow tank regulators, 50 to 100 PSI. the flush valve on the anesthesia machine. |
|
|
Can you use a low pressure self inflating resuscitation bag for jet ventilation?
|
it does not provide enough flow, but you can use it temporarily until a more definitive airway is secure.
|
|
|
Describe the three systems that work reliably and can be easily and inexpensively assembled for trans tracheal jet ventilation:
|
a jet injector blow gun powered by pipeline oxygen pressure.
a jet injector powered by oxygen cylinder regulator. the anesthesia machine flush valve. |
|
|
What are the five complications of high frequency jet ventilation?
|
gas trapping.
bronchoconstriction. failure to adequately ventilate the patient. inaccurate delivery of anesthetic gases. damage to tracheal mucosa and thickened secretions because of inadequate humidification. |
|
|
What is the most common complication to a patient being jet ventilated?
|
tracheal mucosa damage and thickened secretions blocking the airway.
|
|
|
What effect does the high frequency jet ventilation have on the risk of barotrauma?
|
it increases the risk.
|
|
|
List five complications of high frequency trans laryngeal jet ventilation:
|
barotrauma by pneumothorax or mediastinum air.
gastric dilation. inadequate ventilation during inhalation or exhalation. vocal cord motion (not with trans tracheal jet ventilation). blowing tumor, blood, or debris into the depths of the lungs. |
|
|
List seven complications of trans tracheal jet ventilation:
|
barotrauma with pneumothorax.
sub cutaneous emphysema. mediastinum emphysema. difficulty with exhalation. arterial perforation. esophageal puncture with bleeding. damage to tracheal mucosa if non humidified gas is used. |
|
|
What sign is the hallmark of Laryngotracheal damage?
|
stridor.
|
|
|
Is recurrent laryngeal nerve injury a common complication of high frequency trans laryngeal or trans tracheal jet ventilation?
|
no.
|
|
|
Does the descending bellows descend during the inspiratory phase or the expiratory phase?
|
the descending bellows (hanging bellows) descends during the expiratory phase.
|
|
|
Why is the descending bellows a potential disadvantage if a disconnect occurs?
|
if there is a disconnect, the descending bellows will continue its upward and downward movement.
the drive gas pushes the bellows upward during the inspiratory phase and room air is in trained into the breathing system at the site of disconnect because gravity acts on the weighted bellows. |
|
|
Which bellows is safer when there is a disconnect, the ascending bellows or the descending bellows?
|
the ascending bellows is safer.
this is because the ascending bellows will not rise if disconnection occurs. Also, the ascending bellows permits easier detection of circuit leaks or disconnects and less chance of high airway pressures from gas entering the breathing circuit through bellows leaks. |
|
|
Why does looking at the volume return on an a sending bellows not reflect true title volume?
|
the respirometer measures exhaled gases. Title volume settings of the ascending bellows, as indicated on the outside of the plastic container, a different from respirometer readings. This is because of compression of gases, expansion of the breathing circuit closes during mechanical inspiration and the addition of humidifiers.
decreased lung compliance will also force gases that were not used by the patient through the respirometer. |
|
|
The gas that enters the bellows during expiration is what composition?
|
exhaled gases from the patient.
|
|
|
What gas is present outside the bellows ?
|
pressurized oxygen from the ventilator power outlet. It is found between the inside wall of the enclosure and the outside wall of the bellows.
|
|
|
What gases are present within the bellows?
|
all anesthetic gases.
the inside of the bellows is an extension of anesthesia breathing circuit. this is true for both a sending and descending bellows. |
|
|
Cycling of of pressure limited ventilator is triggered by what?
|
inspiratory phase terminates when a preselected pressure is achieved in the ventilator circuit. When this pressure is reached, the ventilator cycles.
|
|
|
Describe the effect of intermittent positive pressure ventilation on the pulmonary circulation:
|
it causes compression of the pulmonary capillaries with the shift of blood from capillaries to pulmonary arteries and veins.
|
|
|
Patient has been on mechanical ventilatory support for two days. You now want to withdraw mechanical support from the patient. List seven objective criteria supporting the feasibility of discontinuing mechanical ventilation:
|
vital capacity greater than 15 mL per kilogram.
AaDO2 less than 350 mmHg while breathing 100% oxygen. PO2 greater than 60 while breathing 50% oxygen. maximal negative inspiratory pressure is more than 20 cm of water. normal pH. spontaneous respiratory rate less than 20. Vd/Vt less than 0.6. |
|
|
What is the suggested protocol to wean patient from SIMV?
|
progressively decrease the number of breaths by 1 to 2 breaths per minute as long as the P. CO2 and respiratory rate remained acceptable.
|
|
|
After weaning and removal from mechanical ventilation, you are ready to remove the tube. What two criteria indicate awake extirpation is appropriate?
|
tolerates two hours of spontaneous breathing on the tee piece.
when patient tolerates SIMV of one to two breaths per minute without deterioration of blood gas, mental status, or cardiac function. |
|
|
What is the effect of intermittent positive pressure ventilation on cardiac output, blood pressure, and venous return?
|
it decreases cardiac output, arterial blood pressure, and venous return.
|
|
|
Explain how intermittent positive pressure ventilation may increase heart rate?
|
reflex from decrease in blood pressure.
|
|
|
Describe intermittent mandatory ventilation:
|
intermittent mechanical inflation of the lungs during periods of spontaneous ventilation.
|
|
|
When do we use intermittent mandatory ventilation?
|
during weaning.
the weaning is initiated by gradually decreasing the number of mechanical breaths delivered each minute. |
|
|
Compare intermittent mandatory ventilation with assist control ventilation:
|
assist control is set for a fixed rate, and initiation will trigger a set tidal volume.
intermittent mandatory ventilation allows spontaneous respirations on their own while the patient is on the ventilator. |
|
|
What is the goal of unifying inspired gas?
|
to improve the mobilization of secretions by increasing water content and decreasing viscosity.
|
|
|
When is ethylene oxide indicated?
|
for objects requiring sterilization that cannot be heated in a steam autoclave.
|
|
|
What three forms of sterilization kill all viruses and all spores?
|
steam autoclave.
ethylene oxide. reading. |
|
|
What are the trade names for glutaraldehyde?
|
cidex and cetylicide.
|
|
|
What does glutaraldehyde kill?
|
all microorganisms, including bacteria, viruses, and spores.
|
|
|
How should nondisposable equipment be sterilized after use on a patient with tuberculosis?
|
glutaraldehyde.
glutaraldehyde kills bacteria, viruses, and spores. |
|
|
What bacterial form is most resistant to destruction?
|
acid fast bacteria, including tuberculosis.
|
|
|
What is the chemical name for household bleach?
|
sodium hypochlorite.
|
|
|
What solutions kills viruses?
|
sodium hypochlorite and glutaraldehyde.
|
|
|
Of the following, what is not killed by alcohol:
bacteria, viruses, spores, fungus? |
spores.
|
|
|
On what items do we use pasteurization ?
|
plastic and rubber anesthesia equipment.
|
|
|
Items that are disinfected with pasteurization are placed in water at what temperature, and for how long?
|
77°C (170°F) for 30 minutes.
|
|
|
Pasteurization kills what organisms?
|
bacteria.
|
|
|
Does the boiling at 100°C kill all organisms?
|
no.
it kills all bacteria, most spores, and most viruses. |
|
|
Alcohol used for disinfection will not kill what agents ?
|
spores and some viruses.
|
|
|
How can you clean laryngoscope blade?
|
steam autoclave.
ethylene oxide. liquid agents such as alcohol, glutaraldehyde are most frequently used. |
|
|
Of the following options, which would be inadequate for disinfecting laryngoscope blade: steam sterilization, gas sterilization, glutaraldehyde, or Betadine?
|
Betadine. Betadine is an antiseptic, and antiseptics are not suitable for disinfecting medical instruments or environmental surfaces.
|
|
|
What is einthovin's triangle?
|
a representation of the placement of three standard limb leads.
|
|
|
Where are the leads place for leads 1,2, and 3?
|
1: left arm positive, right arm negative, left leg ground.
2: right arm negative, left leg positive, left arm ground. 3: left arm negative, left leg positive, right arm ground. |
|
|
Where are the leads placed for v5?
|
the positive electrode for v5 is placed between the mid clavicular line and the fifth intercostal space.
the negative electrode is placed on the left or right arm. |
|
|
What two monitors detect cardiac dysrhythmias?
|
stethoscope.
electrocardiogram. |
|
|
Give five reasons for using electrocardiogram:
|
detect dysrhythmias (lead 1 or 2).
detect ischemia. detect electrolyte abnormalities. calculate heart rate. detect pacemaker malfunction. |
|
|
What is the size of the smallest square on EKG paper?
what does it represent? |
1 mm x 1 mm.
it represents 0.04 seconds. |
|
|
With the 12 lead EKG, where do we place v1?
|
over the fourth intercostal space on the right sternum, over the duration of the right atrium and right ventricle.
|
|
|
What is indicated by PR greater than .21?
|
first degree heart block.
|
|
|
Which lead best detects left ventricular myocardial ischemia?
why? |
v5.
this lead assesses the bulk of the left ventricle. |
|
|
Which leads best detects ischemia resulting from occlusion of the right coronary artery?
|
2,3, avf.
|
|
|
Which EKG leads best detect ischemia resulting from occlusion of the left circumflex?
what part of the heart muscle is supplied by the left circumflex? |
1, avl, v5 thru v6.
this is the lateral myocardium. |
|
|
The modified v5 lead to tax ischemia in what regions of the heart?
|
lateral and anterior walls.
|
|
|
How do you get the modified v5 lead?
|
by placing a left arm lead at the v5 position and selecting lead 1 on the monitor.
|
|
|
What EKG leads best detect ischemia resulting from occlusion of the left coronary artery?
what part of the myocardium is supplied the left coronary artery? |
1,avl,v1 thru v4.
the anterior myocardium is supplied by the left coronary artery. |
|
|
What EKG leads best detect ischemia resulting from occlusion of the left anterior descending?
|
v1 thru v4.
|
|
|
What part of the myocardium is supplied by the left anterior descending?
|
anteroseptal.
|
|
|
What is the characteristic EKG change with digitalis effect?
|
down sloping of the ST segment.
|
|
|
What should be done if sinus dysrhythmia develops?
|
watch closely.
|
|
|
Which is the best standard limb lead for detecting dysrhythmias?
why? |
lead two because it displays large P waves.
|
|
|
What are three characteristics EKG changes with high potassium?
|
prolongation of pr interval.
widening of qrs. Peaked or tented t waves. |
|
|
What is indicated by the appearance of peaked t waves on the EKG?
|
high potassium.
|
|
|
In a patient with low potassium, what change in heart rate may we see?
|
increase.
this is because there is increased automaticity of the atria and ventricles, reflecting a more rapid rate of spontaneous phase four depolarization. |
|
|
What are the four characteristic EKG changes with low potassium:
|
prolongation of pr.
prolongation of qt. flattening of t wave. appearance of prominent u waves. |
|
|
When do we see u waves on the EKG?
|
when there is low potassium.
it is not well understood why this happens. |
|
|
A deficiency of what electrolyte causes broad flattened t waves ?
|
potassium.
|
|
|
What are three characteristics changes on the EKG with high potassium?
|
shortening of qt interval.
slight prolongation of qrs. widening of t wave. |
|
|
Your patient has a wide QRS and a short qt. What electrolyte abnormality do you suspect?
|
high potassium.
|
|
|
What are the three characteristic EKG changes seen with low calcium?
|
prolonged qt.
increased st segment duration. flat or inverted t waves. |
|
|
What is chvostec's sign?
|
prolonged QT interval, increased ST segment duration, and flat or inverted T waves.
this is indicative of low calcium. |
|
|
How are premature atrial beats distinguished from premature ventricular beats?
|
they are generally not followed by a compensatory pause, unlike premature ventricular beats.
|
|
|
Hypertrophy of the left ventricle causes the QRS complex to be exaggerated in both height and depth, especially in what leads?
|
v1 and v6.
high r wave in these leads. |
|
|
What does a diphasic p wave indicate?
|
atrial hypertrophy, particularly of the left atrium.
|
|
|
Name two causes of ST segment depression:
|
sub endocardial ischemia or sub endocardial infarction.
also, don't forget that digitalis may cause down sloping of the ST segment. |
|
|
What are the two causes of ST segment elevation?
|
transmural ischemia (prinzmetal's angina) or transmural infarction.
|
|
|
List six indications for central venous catheter:
|
measure central venous pressure.
rapid infusion of fluids. pacemaker insertion. parenteral nutrition. chemotherapy. to remove air if there is high risk for venous air embolism. |
|
|
Which jugular vein, the right or the left, is preferred for CVP?
why? |
the right internal jugular.
this is because it has a straight course to the superior vena cava, where the left in internal jugular vein as the thoracic duct. |
|
|
What are the three risks of using the left internal jugular vein for central line insertion?
|
increased risk of:
vascular erosion. pleural effusion. puncture of the thoracic duct, leading to cyclothorax. |
|
|
Where should the tip of the central venous catheter be located ?
|
just above the junction of the superior vena cava and the right atrium.
|
|
|
When the central venous catheter is inserted via the right internal jugular, the tip of the catheter on x ray will be seen at what level of thoracic vertebrae?
|
below the inferior border of the clavicles and above the T4 T5 interspace, above the level of the 3rd rib.
|
|
|
Why should the transducer be positioned exactly for measurement of central venous pressure?
|
so that low pressure is can be measured accurately and reproducibly.
|
|
|
What causes the a wave on the CVP waveform?
|
right atrial contraction.
|
|
|
What causes the c wave on the CVP waveform?
|
a slight elevation of the tricuspid valve into the right atrium during ventricular contraction.
|
|
|
What causes the v Wave on the CVP waveform ?
|
blood flow into the right atrium before the tricuspid valve opens.
|
|
|
On the CVP waveform, what does the x dissent indicate?
|
it occurs during ventricular sisterly and represents atrial relaxation with downward displacement of the tricuspid valve.
|
|
|
On the CVP waveform, what does the y dissent indicate?
|
it occurs during nastily and represents early ventricular filling through the open tricuspid valve.
|
|
|
What is normal central venous pressure?
|
0 to 11.
|
|
|
Name four early signs of increased CVP:
|
distended peripheral veins.
increased right heart filling pressures. increased heart rate. bounding peripheral pulses. |
|
|
Name three pathological conditions that may occur with elevated central venous pressure:
|
pulmonary hypertension.
right heart failure. left heart failure. |
|
|
What two situations would cause the CVP reading to be higher than the wedge?
|
right ventricular failure with pulmonary hypertension.
pulmonary embolus. |
|
|
What is the most common complication of CVP?
|
infection.
|
|
|
What is the incidence of pneumothorax with subclavian CVP insertion?
|
1%.
|
|
|
What confirms the entry of the catheter into the internal jugular vein with CVP insertion?
|
the return of desaturated venous blood.
|
|
|
What five sites are acceptable for insertion of PA catheter, in order of ease of insertion?
|
right internal jugular.
external jugular. femoral. subclavian. basilar. |
|
|
What site should not be used for insertion of a PA catheter?
|
left internal jugular.
|
|
|
With right internal jugular insertion of the PA catheter, what is the distance to the right atrium?
|
18 to 22 cm.
|
|
|
With right internal jugular PA catheter insertion, what is the distance to the right ventricle?
|
28 to 32 cm.
|
|
|
With right internal jugular PA catheter insertion, what is the distance to the pulmonary artery?
|
40 to 50 cm.
|
|
|
With right internal jugular PA catheter insertion, what is the distance to pulmonary wedge?
|
45 to 50 cm.
|
|
|
With right internal jugular PA catheter insertion, what is the pressure in the right atrium?
|
6 to 8 mmHg.
|
|
|
With right internal jugular PA catheter insertion, what is the pressure in the right ventricle?
|
25/0.
|
|
|
With right internal jugular PA catheter insertion, what is the pressure in the pulmonary artery?
|
25/12.
|
|
|
With PA catheter insertion, what is the pressure with pulmonary wedge?
|
2 to 12.
|
|
|
Specify six indications for pulmonary artery catheter:
|
known cardiovascular disease.
where cross clamping of the thoracic aorta is anticipated. respiratory failure. suspected were diagnosed pulmonary embolus. previous cardiac surgery. when pneumonectomy is anticipated. |
|
|
List six additional indications for PA catheter insertion:
|
when fluid shift is anticipated.
sepsis. receiving continuous inatropes or vasodilators. pulmonary hypertension. cor pulmonale. treatment with bleomycin. |
|
|
What ejection fraction and cardiac index are suggestive of poor left ventricular function indicating the need for PA monitoring?
|
ejection fraction less than 40%.
cardiac index less than 2.1. |
|
|
What is the most severe complication of pulmonary artery monitoring?
|
artery perforation and hemorrhage.
|
|
|
What three actions should be taken to treat pulmonary artery perforation and hemorrhage?
|
replace volume.
add peep. isolate involved lung with double lumen tube into the non bleeding lung. |
|
|
What is the most common complication with the insertion of PA catheter?
|
arrhythmia as a catheter goes into the right ventricle.
|
|
|
What drug is used to treat arrhythmias that occur during placement of a PA catheter?
|
lidocaine.
|
|
|
What is the balloon capacity for number five PA catheter?
|
1.5 mL.
|
|
|
What is the most commonly used size of PA catheter?
|
seven French.
|
|
|
What are two causes of PA catheter not reaching the pulmonary artery?
|
perforation.
coiling. |
|
|
What is the range of normal pulmonary artery systolic and diastolic pressure?
|
15 to 30.
4 to 12. |
|
|
Your pulmonary catheter is properly wedged and a large v wave appears.
what is the cause? |
most likely mitral regurgitation.
|
|
|
What three measures are taken to increase the accuracy and precision of cardiac outputs measured by thermal dilution?
|
triplicate determinations are averaged with a delay of 60 to 90 seconds in between.
perform the measurement at end expiration (this reduces variability.) ensure that the rate of injection in volume of injecting are constant. |
|
|
What interferes with cardiac output determinations using thermal dilution method?
|
electric cautery. Do not perform cardiac output measurements during electric cautery.
|
|
|
Is the area under the thermal dilution curve directly related to or inversely related to cardiac output?
|
cardiac output is inversely proportional to the area under the thermal dilution curve.
|
|
|
If the area under the patient's thermal dilution curve is getting smaller, is the patient's cardiac output increasing or decreasing?
|
the smaller the area under the curve, a greater cardiac output.
|
|
|
If cardiac output injecting volume is too small, how will this affect measurement?
|
there will be a false high measurement.
|
|
|
If cardiac output injecting volume is too large, how will this affect the measurement?
|
there will be a false low.
|
|
|
Discuss the cardiac output curve (temperature time curve) and injecting volume that is too high or too low:
|
cardiac output is inversely proportional to the area under the temperature time curve.
the area under the curve will leak larger if greater volume is injected, so cardiac output will be falsely low. the area under the curve will be smaller if a smaller volume is injected, so cardiac output will be falsely high. |
|
|
Insufficiency of either of what two valves may lead to a falsely high thermal dilution cardiac output reading?
|
either tricuspid or pulmonic insufficiency will lead to falsely high thermal dilution readings.
|
|
|
A patient with tricuspid regurgitation has a thermal dilution cardiac output reading of 5 L per minute. Is this accurate ?
explain: |
this reading is falsely high.
tricuspid regurgitation produces a falsely elevated reading. |
|
|
With thermal dilution cardiac output monitoring, you inject 10 mL of cold injectate when the cardiac output computer is set for 5 mL. How will this affect the cardiac output reading?
|
the reading will be lower than the true cardiac output.
|
|
|
What is the relationship of lvedv, paop, lvedp, and ladp?
|
in the absence of mitral stenosis or pulmonary hypertension, they are all equal, and equal preload.
|
|
|
How does wedge pressure reflect lvedp in the patient with mitral valve stenosis?
|
lvedp is directly related to wedge, assuming there is an open conduit from the catheter tip to left ventricle.
since stenosis of the mitral valve impedes the flow of blood into the left ventricle, lvedp will be lower than wedge. so, wedge overestimates lvedp in the patient with mitral valve stenosis. |
|
|
How does wedge reflect lvedp in the patient with mitral valve insufficiency?
|
wedge reflects lvedp accurately with mitral valve insufficiency.
This is because the conduit between the tip of the catheter and the left ventricle is open. |
|
|
Identify three situations where pulmonary capillary wedge pressure will be greater than left ventricular end diastolic pressure:
|
mitral stenosis.
elevated alveolar pressure. pulmonary venous obstruction. |
|
|
Wedge pressure will be less than left ventricular edp in patients who have what valve problem?
explain: |
wedge will underestimate lvedp in patients with aortic regurgitation.
blood flowing back into the left ventricle from the aorta during diastole closes the mitral valve before systole actually begins. true end diastolic pressure cannot be detected by the wedged pulmonary artery catheter because the mitral valve is closed. |
|
|
Does pulmonary artery diastolic pressure reflect left ventricular end diastolic pressure (left ventricular preload)?
|
yes.
it is often used as an alternative to measuring wedge. |
|
|
After giving 200 mL of intravenous fluid, pulmonary artery systolic/diastolic increases from 22/6 to 40/25.
is this normal or abnormal? |
it is abnormal.
a small increase would be normal, according to starlings law. the most likely explanation is decreased left ventricular compliance (diastolic dysfunction). with decreased left ventricular compliance, small increase in left ventricular volume will produce a large increase in lvedp. This increase is reflected by the increase in pulmonary artery pressure. another cause could be systolic dysfunction. |
|
|
What three valuable cardiovascular parameters are obtained from arterial line?
|
left ventricular volume.
left ventricular function. systemic vascular resistance. |
|
|
How will arterial line tracing change it air gets into the line?
|
the pattern gets dampened.
|
|
|
Where is the proper placement of the pressure transducer in a sitting position for arterial line?
|
at the base of the year.
|
|
|
What does the dicrotic notch come from?
|
closure of the aortic valve.
|
|
|
When does false elevation of arterial line monitoring occur?
|
decreased arterial compliance.
decreased transducer system frequency (ringing or overshoot) producing distortion of the waveform. |
|
|
How can you clean laryngoscope blade?
|
steam autoclave.
ethylene oxide. liquid agents such as alcohol, glutaraldehyde are most frequently used. |
|
|
Of the following options, which would be inadequate for disinfecting laryngoscope blade: steam sterilization, gas sterilization, glutaraldehyde, or Betadine?
|
Betadine. Betadine is an antiseptic, and antiseptics are not suitable for disinfecting medical instruments or environmental surfaces.
|
|
|
What is einthovin's triangle?
|
a representation of the placement of three standard limb leads.
|
|
|
Where are the leads place for leads 1,2, and 3?
|
1: left arm positive, right arm negative, left leg ground.
2: right arm negative, left leg positive, left arm ground. 3: left arm negative, left leg positive, right arm ground. |
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|
Where are the leads placed for v5?
|
the positive electrode for v5 is placed between the mid clavicular line and the fifth intercostal space.
the negative electrode is placed on the left or right arm. |
|
|
What two monitors detect cardiac dysrhythmias?
|
stethoscope.
electrocardiogram. |
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|
Give five reasons for using electrocardiogram:
|
detect dysrhythmias (lead 1 or 2).
detect ischemia. detect electrolyte abnormalities. calculate heart rate. detect pacemaker malfunction. |
|
|
What is the size of the smallest square on EKG paper?
what does it represent? |
1 mm x 1 mm.
it represents 0.04 seconds. |
|
|
With the 12 lead EKG, where do we place v1?
|
over the fourth intercostal space on the right sternum, over the duration of the right atrium and right ventricle.
|
|
|
What is the advantage over of five lead EKG over a three lead EKG?
|
three lead is limited in detecting ischemia.
the five lead EKG can also better distinguish between atrial and ventricular dysrhythmias. |
|
|
Name the leads monitored with three lead EKG:
|
one, two, three.
|
|
|
Name the leads monitor with five lead EKG:
|
one, two, three,avr, avl, avf, as well as 13 Cordele unipolar lead which is usually placed in the v5 position.
|
|
|
How many millivolts a generated on the skin by EKG signals?
|
1 mV, which is 1000 micro volts.
|
|
|
What is indicated by PR greater than .21?
|
first degree heart block.
|
|
|
Which lead best detects left ventricular myocardial ischemia?
why? |
v5.
this lead assesses the bulk of the left ventricle. |
|
|
Which leads best detects ischemia resulting from occlusion of the right coronary artery?
|
2,3, avf.
|
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|
Which EKG leads best detect ischemia resulting from occlusion of the left circumflex?
what part of the heart muscle is supplied by the left circumflex? |
1, avl, v5 thru v6.
this is the lateral myocardium. |
|
|
The modified v5 lead to tax ischemia in what regions of the heart?
|
lateral and anterior walls.
|
|
|
How do you get the modified v5 lead?
|
by placing a left arm lead at the v5 position and selecting lead 1 on the monitor.
|
|
|
What EKG leads best detect ischemia resulting from occlusion of the left coronary artery?
what part of the myocardium is supplied the left coronary artery? |
1,avl,v1 thru v4.
the anterior myocardium is supplied by the left coronary artery. |
|
|
What EKG leads best detect ischemia resulting from occlusion of the left anterior descending?
|
v1 thru v4.
|
|
|
What part of the myocardium is supplied by the left anterior descending?
|
anteroseptal.
|
|
|
What is damping of transducers?
what causes damping? |
how quickly the system comes to rest after being set in motion.
air bubbles, thrombus formation, and kinking may damp the system. |
|
|
List six arterial cannulation sites, in order of preference:
|
radial.
ulnar. brachial. axillary. femoral. dorsal. |
|
|
Which site is the most common for arterial line?
|
radial.
|
|
|
Which type of catheters are preferred for radial arterial line?
|
non tapered catheters.
|
|
|
Why is the ulnar artery more difficult to insert a catheter into?
|
it is deeper and more torturous.
|
|
|
Which artery is the primary supply of blood flow to the hand?
|
the ulnar artery.
|
|
|
Where is the insertion site for the brachial artery?
|
medial to the biceps tendon.
|
|
|
What is the risk with brachial arterial line insertion?
|
median nerve damage.
|
|
|
Where is the insertion site for the axillary artery?
|
at the Junction of the pectoral and deltoid muscles.
|
|
|
What is the risk with axillary arterial line insertion ?
|
nerve damage from hematoma.
|
|
|
What is the advantage to femoral arterial line insertion during emergencies?
|
it provides easy access in low flow states.
|
|
|
What are the risks with femoral arterial line insertion?
|
the femoral artery is prone to pseudo aneurysm and formation of atheroma.
there is also risk for retroperitoneal bleed. |
|
|
Name one disadvantage of dorsal pedal a lines:
|
they are farthest from a higher so the waveform is more distorted, leading to higher systolic pressure estimates.
|
|
|
Name six factors that could cause arterial lines to develop thrombosis:
|
duration of catheterization.
larger catheter (18 versus 20gauge). catheter material (tapered Teflon has less thrombosis than polypropylene.). proximal emboli. prolonged shock. pre existing vascular disease. |
|
|
How do you determine the correct width of a blood pressure cuff?
|
the width of the blood pressure cuff should be 40% of the arm circumference.
|
|
|
Is the blood pressure reading erroneously high or low when the cuff is too narrow or wrapped to loosely?
|
erroneously high.
|
|
|
Inaccuracy of blood pressure measurements by sphygmomanometer is most often due to what?
|
improper cuff size.
|
|
|
When using a target, where can most damage occur to a limb, proximal, distal, or under the cuff?
|
the pressure under the cuff is more damaging than distal to the cuff.
|
|
|
Where is the ideal placement of the esophageal stethoscope?
|
in the lower third of the esophagus.
|
|
|
The use of an esophageal stethoscope is contraindicated in patients with either of what two conditions:
|
esophageal perforation.
patient with liver disease who could have esophageal varices. |
|
|
What seven cardiac parameters are observed or estimated with two dimensional transesophageal echocardiogram?
|
ventricular wall motion (looking for ischemia.)
valve motion. estimations of end diastolic and end systolic volumes (to measure ejection fraction.) cardiac output. blood flow characteristics. intracardiac air. intracardiac masses. |
|
|
Is tee a more sensitive indicator of ischemia than EKG?
|
yes.
|
|
|
List four types of abnormal wall motion on tee:
|
hypokinesis (less than normal motion.)
hyperkinesis. a kinesis (absence of wall motion.) dyskinesis (the ventricle has a paradoxically outward movement.) |
|
|
What is the frequent cause of end titled CO2 tracing the reaching baseline (zero mmHg) during inspiration?
how can this be corrected? |
rebreathing of dead space volume.
remove the dead space. |
|
|
Your patient is receiving agent/narcotic/nitrous oxide. You notice elevation in the end title CO2 baseline. Ventilator settings are adequate. What do you do?
why? |
increase fresh gas flow. For some reason, the patient is rebreathing CO2.
|
|
|
What three conditions could cause the end title CO2 to increase in inactivated patient under general anesthesia?
|
CO2 production exceeds ventilation (like with hyperthermia.)
exogenous source of CO2 present (like laparoscopic insufflation, bicarbonate infusion, or rebreathing.) alveolar ventilation decreases. |
|
|
And title CO2 of 5 is indicative of what?
|
esophageal intubation.
|
|
|
What causes the burbling or feathering seen on the plateau of the entitled CO2 waveform?
|
cardiogenic oscillations.
|
|
|
What will happen to and title CO2 if the patient is ventilated and ventilation perfusion mismatch develops?
|
and title CO2 rate decrease because the ability to blow up CO2 decreases with VQ mismatching.
|
|
|
Where on the The capno graph tracing is found dead space plus alveolar ventilation?
|
dead space plus alveolar ventilation is found throughout expiration on the entitled CO2 tracing.
|
|
|
What gases are measured by mass spectrometry?
|
CO2, oxygen, nitrogen, and inhaled anesthetics such as nitrous oxide, isoflurane, sevoflurane, desflurane, halothane, and enflurane.
|
|
|
When using a mass spectrometer, what is the primary concern?
|
the sampling interval, while normally short on a to provide sufficient early warning of most events and physiological changes, may not be. Short enough for emergencies and sampling rate may not be rapid enough.
|
|
|
What happens to the gas sample drawn from the side port into the analyzer compartment of the mass spectrometer?
|
the gas sample is ionized by electron beam and passed through a magnetic field.
|
|
|
What happens to the ions formed by the passing gas through the electron beam of the mass spectrometer?
|
they follow a curved path as they pass through the magnetic field.
Ions with greater mass to charge ratios are least deflected and follow the curved path with the greatest radius. conversely, gases with the smallest mass to charge ratio are deflected most and follow the curved path with the smallest radius. |
|
|
How is the concentration of gas determined by the mass spectrometer?
|
molecules of different mass are deflected at varying angles when passed through the magnetic field. Detectors are placed at specific locations to count the number of molecules hitting the detector, which is then converted to a concentration of the particular gas.
|
|
|
Where should the mass spectrometry gas monitor sampling line replaced?
|
from side port on the elbow inserted between the endotracheal tube and the y piece of the circle system.
|
|
|
What three general problems can't be detected by mass spectrometry?
|
the mass spectrometer can:
identify equipment problems. identify the ventilator problems (low CO2, high CO2, emboli). alert the anesthetist to vaporizer malfunction. |
|
|
List 13 specific problems that can't be detected by mass spectrometry:
|
error in gas delivery (CO2, oxygen, nitrogen, or inhaled agent.
anesthesia machine elf function. disconnection. vaporizer malfunction. anesthesia circuit leaks. endotracheal tube cuff leak. poor mask or LMA hypo ventilation. malignant hyperthermia. airway obstruction. air embolism. circuit hypoxia. vaporizer overdose. |
|
|
Can the mass spectrometer detect ventilation perfusion mismatch?
explain your answer: |
no.
this is because the mass spectrometer does not assess PO2. |
|
|
Give two limitations of the mass spectrometer:
|
lung measurement delays may be encountered.
administration of isoproterenol will give false high measurement. |
|
|
What limitation exists when using mass spectrometry with a closed system?
|
the gas sampling system may withdraw from the system more gas per minute for analysis than the volume of oxygen introduced.
hypoxemia could result. |
|
|
A mass spectrometer reads 5% CO2 at sea level. What is the partial pressure of CO2?
what law is the basis for this calculation? |
(5%/100) x 760 equals 38 mmHg.
5% CO2 exerts a partial pressure of 38. Dalton's law of partial pressure is the basis for this calculation. |
|
|
What are the contraindications to pulse oximetry?
|
there are no contraindications to pulse oximetry.
|
|
|
List four examples of low perfusion states that can cause pulse oximetry artifact:
|
low cardiac output.
anemia. hypothermia. increased systemic vascular resistance. |
|
|
Give 10 factors, unrelated to low perfusion, that interfere with accurate pulse oximetry readings:
|
carboxy hemoglobin.
methemoglobinemia. low oxygen saturation (it comes inaccurate.) excessive from ambient light or overhead infrared lights. tremors or vibrations of the patient. methylene blue. venous pulsations. deeply pigmented skin. fingernail polish. light leaking from the light sources to the light detectors. |
|
|
Do fetal hemoglobin or bilirubin interfere with pulse oximetry?
|
no.
|
|
|
What two hemoglobin alterations will yield false high pulse oximetry readings?
|
carboxy hemoglobin.
methemoglobin. |
|
|
Describe how methemoglobin produces false high saturation readings:
|
methemoglobin has the same absorption coefficient at both red and infrared wavelengths. The resulting 1:1 ratio corresponds to a saturation reading of 85%, so the oximeter is "locked" at 85% by the presence of methemoglobin.
desaturation is less than 85%, the reading will be falsely high. |
|
|
Which of the following will not cause pulse oximetry artifact:
fetal hemoglobin, hemoglobin less than 7. bilirubin. carboxy hemoglobin. methemoglobin? |
fetal hemoglobin and bilirubin do not cause pulse oximetry artifact.
|
|
|
Explain how the pulse oximeter works:
|
two different wavelength of light are used. One is visible (red at 660 nm) and the other is infrared (at 990 nm.)
infrared light is absorbed by oxyhemoglobin and red light is absorbed by deoxyhemoglobin. The differences in absorption are used to calculate oxygen saturation. |
|
|
Identify the two light sources in the photo diode of the pulse oximeter:
|
red light 660 nm.
infrared light 990 nm. |
|
|
what two principles are combined in the pulse oximeter to measure oxygen saturation in arterial blood?
|
pulse oximeter is combined the principles of oximetry and plethysmography to measure oxygen saturation in the arterial blood.
|
|
|
What does a finger plethysmograph detect?
|
changes in finger volume.
it uses light emitting diode and a photoelectric cell to detect changes in finger volume. |
|
|
the Lambert beer law is based on what observation and applies to monitoring modality?
|
it is based on the observation that oxygenated hemoglobin and reduced hemoglobin differ in their absorption of red and infrared light.
this law forms the basis of pulse oximetry. |
|
|
Can the pulse oximeter detect ventilation perfusion mismatch?
why or why not? |
yes.
this is because PO2 decreases when ventilation perfusion mismatch develops. since saturation decreases when PO2 decreases below 100, pulse oximeter can detect ventilation perfusion mismatch. |
|
|
What monitor can detect aspiration ?
|
pulse oximeter.
this is because low saturation occurs when ventilation perfusion mismatch develops. |
|
|
What five monitors can detect disconnection?
|
pulse oximeter.
mass spectrometer. entitled CO2. stethoscope. spirometer. |
|
|
What are the best monitors to detect disconnection?
|
entitled CO2 and spirometer.
|
|
|
What four monitors can detect esophageal intubation?
|
pulse oximeter.
mass spectrometer. end titled CO2. stethoscope. |
|
|
What two monitors can detect bronchial intubation?
|
pulse oximeter and stethoscope.
|
|
|
What monitor can detect pneumothorax question mark
|
pulse oximeter.
the ventilation perfusion mismatch may cause drop in saturation. |
|
|
What two measurements assess blood oxygen?
|
PO2 and saturation.
|
|
|
Why would we perform EEG monitoring?
|
to assess the adequacy of cerebral perfusion during surgery.
|
|
|
Identify one specific procedure where we would do EEG monitoring:
|
carotid endarterectomy.
|
|
|
How many millivolts a generated on the skin by EEG signals?
how many micro volts is this? |
0.1 mV.
this is 100 micro volts. |
|
|
In what micro volts range are brain waves generally?
|
10 to 100.
|
|
|
When would you use sensory evoked potential monitoring?
|
to assess continually the function and integrity of neural pathways, including the spinal cord (somatosensory) or cranial nerve eight (brainstem auditory), or cranial nerve two (visual).
evoked potentials are used during resection of spinal cord tumors, corrected surgery of the spine, and cranial tumor resection. |
|
|
How are somatosensory elicited?
|
they are listed by electrically stimulating tibial, ulnar, or radial nerves.
|
|
|
What types of neurons are stimulated with somatosensory evoked potential's?
|
low threshold sensory neurons (those that carry touch and pressure sensations) are excited.
|
|
|
What is the value of somatosensory evoked potential monitoring?
|
they monitor the integrity of the posterior (dorsal) spinal cord where the sensory tracts (cutaneus anf gracilis) of the dorsal lemniscal system are located.
|
|
|
Somatosensory evoked potential monitoring processes the integrity of which regions of the spinal cord:
dorsal, lateral, or ventral? |
dorsal.
|
|
|
Where are recording electrodes placed for somatosensory evoked potential monitoring if the tibial nerves are stimulated bilaterally?
|
between the ears on the scalp.
the crucial electrode is placed midway between each year. |
|
|
What happens to the somatosensory evoked potential when the patient undergoing laminectomy is paralyzed with muscle relaxant?
|
nothing.
neuromuscular blockade will not alter transmission of action potentials in the sensory tract. |
|
|
What effect does Paul anesthetics have on somatosensory evoked potential's?
|
they produce dose dependent increases in latency and decreases in amplitude of the evoked potentials.
especially in doses greater than one Mac. |
|
|
Which volatile anesthetic least depresses the amplitude and increases the latency of somatosensory evoked potentials ?
|
halothane.
|
|
|
Which volatile agent most depresses amplitude and most increases latency of somatosensory evoked potential's?
|
enflurane.
|
|
|
How does nitrous oxide affect latency and amplitude of somatosensory evoked potentials?
|
nitrous oxide decreases able to and causes no change in latency when used with narcotic or alone.
|
|
|
List five physiologic factors that may alter sensory evoked potential's:
|
temperature.
low blood pressure. hypoxia. low CO2. isovolemic hemodilution. |
|
|
Which physiologic factor has the greatest effect on sensory evoked potentials?
|
altered temperature.
|
|
|
what effect does hypothermia have on evoked potentials?
|
hypothermia will increase latency and decrease amplitude by 1ms for every one degree Celsius in temperature.
|
|
|
What effect does hyperthermia have on sensory evoked potentials?
|
it will decrease in amplitude by up to 15%, and potential are lost at 42°C.
|
|
|
What physiologic factor least effects sensory evoked potentials?
|
hemodilution.
|
|
|
flow through what spinal arteries is monitored by somatosensory evoked potentials?
|
the posterior spinal arteries.
|
|
|
Brainstem auditory evoked potential monitoring is useful during operations involving which nerves?
|
cranial nerve eight.
|
|
|
Is brainstem auditory evoked potential monitoring appropriate for surgery for acoustic neuroma?
why or why not? |
yes.
this is because cranial nerve eight carries acoustic messages. |
|
|
Monitoring of which evoked potentials may be useful during pituitary surgery?
|
visual.
this is because visual evoked potential monitoring is helpful in assessing direct compression of or compromise blood flow to the optic nerve and optic chiasm. |
|
|
Which evoked potential monitoring is used during trans sphenoid surgery?
|
visual evoked potential.
it is done if the tumor is large and involves the optic nerves (cranial nerve two.) |
|
|
Which evoked potential is most easily depressed by volatile anesthetics?
|
visual evoked potential.
|
|
|
Which evoked potential is most resistant to depression by volatile anesthetics?
|
brainstem auditory evoked potential's.
|
|
|
Which evoked potential is intermediate resistant to volatile anesthetics?
|
somatosensory evoked potential.
|
|
|
Where are motor evoked potentials stimulated?
|
over or in the motor region of the cerebral cortex.
|
|
|
How are motor evoked potentials stimulated ?
|
by either trans cranial electrical stimulation.
or trans cranial magnetic stimulation. or direct stimulation of the motor cortex with an electrode. |
|
|
Where they motor evoked potential to be monitor?
|
over or at:
the spinal cord. a peripheral nerve. the involve muscle. never at the site of stimulation. |
|
|
What is the wake up test, and how is it performed?
|
the wake up test is used to assess the integrity of the spinal motor pathways.
it is performed by lightning the anesthetic depth. The patient is asked to squeeze a hand and move his/her feet and toes. after these maneuvers are performed, anesthesia is quickly deepened. |
|
|
The wake up test monitors what region of the spinal cord, dorsal, lateral, or ventral?
|
ventral, which is supplied by the anterior spinal artery.
|
|
|
What complications can occur during the wake up test?
|
exhibition in the prone position.
recall. myocardial ischemia. self injury. this lodgment of instrumentation. air embolism from open sinuses if the patient is breathing spontaneously and inhaled vigorously. |
|
|
What agents will not alter bispectral index monitoring?
|
opioids or analgesics.
nitrous oxide. |
|
|
What effect does ketamine have on bispectral index monitoring?
|
minimal.
|
|
|
What two lasers are commonly used for laser surgery on the upper airway?
|
carbon dioxide lasers.
nd yag lasers. |
|
|
List five surgical advantages of using nd yag lasers:
|
less bleeding.
ability to coagulate small vessels. maintenance of sterile conditions. less tissue trauma. increased precision of dissection. |
|
|
State what the CO2 laser does and what is commonly used for:
|
CO2 laser is well absorbed by water and superficial surface cells.
it is commonly used for laryngeal lesions. |
|
|
Why is the carbon dioxide laser suitable for removing lesions on the vocal cords and larynx?
|
because the beam is so strongly absorbed by water, it damages tissues only to a depth of 200 µm.
because of this, the laser can cleanly remove lesions without damaging underlying tissues. |
|
|
Laser light offers surgeon what advantages?
|
excellent precision and hemostasis with minimal postoperative edema or pain.
|
|
|
Why is the CO2 laser most commonly used in medical practice?
|
because it has a longer wavelength and is absorbed to a greater extent by water, so less tissue is penetrated.
|
|
|
What is the cause of recurrent respiratory papillomatosis?
|
human papilloma virus.
|
|
|
What is the most effective treatment of respiratory papillomatosis?
|
surgical removal, most commonly, laser vaporization.
|
|
|
A carbon dioxide laser will be used to remove human papilloma virus from the airway. What three concerns should you have about conducting anesthesia for this procedure?
|
airway fire is the most threatening hazard of airway laser surgery.
the major risks for operating room personnel and the patient during laser surgery are damaged to the eyes and cutaneous burns from errant (reflected) laser rays. laser smoke plume produces debris, possibly including aerosolization of human papilloma virus. |
|
|
Carbon dioxide laser will be used to remove human papilloma virus. What three safety precautions must be taken?
|
do everything possible to prevent an airway fire and be prepared to treat an airway fire.
all operating room personnel must wear safety glasses appropriate for CO2 laser and the patient's eyes should be taped shut. transmission of human papilloma virus can be minimized by suctioning the laser plume, wearing gloves, and using high efficiency mask. |
|
|
What is the most serious complication of airway laser surgery?
|
fire in the airway.
|
|
|
What two endotracheal tubes resist burning when the laser is being used?
|
double cuffed silicone coated metal tubes of the safest but most expensive.
wrapping up regular endotracheal tube in metallic tape increases the mean time to admission from 40 to 60 seconds. |
|
|
What are the first two actions to take in an airway fire?
|
stop ventilation.
remove the tube. |
|
|
After the first two actions following an airway fire, then what do you do?
|
immediately turn off/disconnect oxygen.
mask ventilate, reinsert endotracheal tube. diagnose injury, bronchoscopy/laryngoscopy. administer short term steroids. monitor the patient released 24 hours. administer antibiotics, postoperative ventilation if necessary. |
|
|
Which gases are safe to use during laser surgery?
|
30% oxygen in nitrogen or helium.
helium may be useful to replace nitrous oxide and maintain oxygen concentrations at most acceptable level. |
|
|
High concentrations of which two gases should be avoided during laser surgery of upper airway requiring general endotracheal anesthesia?
|
oxygen and nitrous oxide.
|
|
|
During endoscopic laser surgery, what anesthetic gas with best be avoided?
why? |
nitrous oxide.
this is because oxygen and nitrous oxide both support combustion. |
|
|
Since oxygen and nitrous oxide support combustion, what can you dilute with oxygen to prevent fire laser surgery?
|
nitrogen, air, or helium.
|
|
|
The concentration of inspired oxygen should be reduced to less than what percentage during laser surgery?
|
less than 30%.
|
|
|
Describe the second most serious complication of the laser for airway surgery, and explain how this potential problem can be minimized:
|
damage to the eyes.
operating room personnel should wear goggles, and the patient's eyes should be covered. |
|
|
List four actions that can be taken for the patient will undergo laser surgery:
|
tape the eyes and cover with moist gauze.
25 to 30% oxygen administered with nitrogen or helium. fire resistant endotracheal tube. endotracheal tube cuff can be filled with saline as a precaution against being hit by laser. |
|
|
What is the most important precaution whenever airway nd yag lasers are used an endotracheal tube in place?
|
inspired oxygen concentration should be titrated to the lowest possible level.
specially constructed endotracheal tubes has both advantages and disadvantages during airway laser surgery, so the use of the low priority compared with other measures to prevent airway fire. the most important thing is to decrease inspired oxygen. |
|
|
Describe the ocular damage that may occur from the laser based upon the laser wavelength:
|
ultraviolet lasers are 200 to 315 nm in wavelength, may cause corneal photo keratitis and cataract formation.
near ultraviolet visible and near infrared are 400 to 1400 nm (argon, ktp yag, nd yag, and ruby lasers cause retinal damage. mid IR (1400 to 3000 nm) lasers may cause cataract. far IR lasers (3000 to 10,000 nm) such as CO2 laser, cause corneal burns. |
|
|
Can you rely on the color of protective lenses to indicate they are used for specific lasers?
|
no.
|
|
|
What protective eyewear criteria should be adhered to for proper ocular protection during laser surgery?
|
protective lenses must have the appropriate optical density and reflective properties based upon the wavelength of the beams encountered.
for example, protective eyeware for nd yag laser should be marked "OD5 or greater for 1064 nm. |
|
|
what site gives the most reliable approximation of core body temperature?
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the lower 25% of the esophagus gives a reliable approximation of blood and cerebral temperature.
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What site/method is the most accurate indication of body temperature ?
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the tympanic membrane and aural canal temperature correlate well with esophageal temperature.
truly, the most accurate reflection of temperature is pulmonary artery catheter thermistor, but this is not routinely performed. |
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Which temperature monitoring device best correlates with brain temperature?
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tympanic thermometer.
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What three things are grounded in the operating room?
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the power supply.
the patient. the floor. |
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Is the electrical equipment in the operating room grounded or isolated?
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it is isolated with isolation transformers.
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Electrical equipment in the operating room is monitored by what?
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line isolation monitor.
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What is the function of the line isolation monitor?
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it monitors isolation of the transformer in every operating room suite.
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How does the line isolation monitor work?
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every operating room has electricity that is isolated from the main power by an isolation transformer.
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What triggers the alarm of the line isolation monitor?
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if either the isolated power line is less than 6000 ohms or if a fault would draw more than 2 milliamps.
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What should be done if the all I'm of the line isolation monitor goes off?
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unplug the equipment that triggered it to prevent someone from being electrically shocked.
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How is macroshock, or, electrocution, prevented in the operating room?
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by isolating the operating room power supply from the ground.
the operating room power supply is isolated from the ground by an isolation transformer which is not grounded and provides to live uncrowded voltage lines for operating room equipment. |
