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167 Cards in this Set
- Front
- Back
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Contemporary inhaled volatile anesthetics exist in liquid state at temperatures of what?
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Below 20 C
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What is vapor composed of?
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Molecules(gas phase) of substance that is liquid at room temperature and 1 ATM of pressure.
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When a volatile liquid is in a closed container, molecules escape from the liquid phase to the vapor phase until the number of molecules in the vapor phase is ______.
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Constant
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Molecules in the vapor phase bombard the wall of the container and create a pressure known as?
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Saturated vapor pressure (VP)
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As the temperature increases what happens to the molecules and vapor pressure?
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More molecules enter the vapor pressure and the vapor pressure increases.
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What is the definition of boiling point?
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A liquid is defined as the temperature at which VP equals the atmospheric pressure.
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What is the vapor pressure of Sevoflurane? (mmHg)
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160 mmHg
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What is the boiling point of sevoflurane? Celsius
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58.5 Celsius
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What is a mac percentage of sevoflurane? Precentage
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1.7%
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What is the vapor pressure of Isoflurane? (mmHg)
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238 mmHg
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What is the boiling point of isoflurane? Celsius
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48.5 C
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What is a mac percentage of isoflurane? Precentage
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1.15%
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What is the vapor pressure of Desflurane? (mmHg)
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664 mmHg
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What is the boiling point of Desflurane? Celsius
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23.5 C
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What is the MAC % of Desflurane?
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6%
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What is the vapor pressure of Halothane? (mmHg)
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241 mmHg
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What is the boiling point of Halothane? Celsius
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50.2 C
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What is the MAC % of Halothane?
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0.77%
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What is the vapor pressure of Ether? (mmHg)
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175 mmHg
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What is the boiling point of Ether? Celsius
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56.6 Celsius
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What is the MAC % of Ether?
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1.7%
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Which anesthetic has the lowest vapor pressure?
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Sevoflurane
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Which anesthetic has the highest vapor pressure?
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Desflurane
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What is the boiling point of Desflurane in Fahrenheit and what is the significance?
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23.5 C or 74.3 F.
These temperatures that may be encountered in clinical settings in the OR for pediatric and burn patients. |
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What happens does the remaining liquid in the chamber after evaporation?
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It cools because heat energy is carried from the liquid with the energetic, mobile, evaporating molecules.
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What is an azeotropic mixture?
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A liquid mixture of two or more components and a unique mixture with a constant boiling point.
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What happens to the vaporization rate of an anesthetic if it is cooled?
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It slows the vaporization rate.
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What is the latent heat of vaporization?
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The amount of energy that is consumed for a given liquid to be converted to a vapor. More precisely defined the number of calories required to change 1 gram of liquid into vapor without a change in temperature.
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What is the specific heat of a substance?
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Number of calories required to increase the temperature of 1 gram of a substance by 1 C. Substance can be solid, liquid, or gas.
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What is thermal conductivity?
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It is a measure of the speed at which heat flow through a substance. The higher the thermal conductivity, the better the substance conducts heat.
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What does MAC stand for and how is it defined?
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Minimum alveolar concentration of concentration of inhaled anesthetic required to prevent 50% of subjects from gross purposeful movement in response.
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What helps anesthetics from cooling?
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Materials such as copper which has high thermal conductivity (transferring environmental easily to liquid anesthetic) and high thermal capacity (acting as thermal reservoir to help stabilize liquid anesthetic temperature).
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What type of vaporizers are the Tec 4, Tec 5, Tec 7?
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Variable-bypass vaporizers
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What type of vaporizer hold desflurane?
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Tec 6
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What is the purpose of the control dial setting?
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Determines the ratio of flow that goes through the bypass chamber and the vaporizing chamber as fresh gas from the flow meters enters the vaporizer inlet.
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Each of vaporizer is equipped with an automatic temperature-compensating device why?
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It maintains constant vaporizer output over a wide range of operating temperatures.
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What does flow over refer to?
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It refers to the method of vaporization.
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What anesthetics are used in the variable-bypass vaporizers?
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Halothane, enflurane, isoflurane, sevoflurane, but NOT DESFLURANE.
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Who fills the vaporizer chamber with liquid anesthetics through the filler port?
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The Operator
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What happens if the vaporizer is overfilled or tilted?
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Liquid anesthetic can spill into the bypass chamber which could carry saturated anesthetic vapor which would result in OVERDOSE.
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What are the five components of the Generic Variable Bypass Vaporizer?
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Concentration Dial
Bypass chamber Vaporizing Chamber Filler port Filler cap |
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What regulates the relative flow rates through the bypass and vaporizing chambers?
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Concentration control dial
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Where does the flow come from that enters the inlet of the vaporizer?
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Flow meters
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The maximum safe fill level is predetermined by the position of what?
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The filler port
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What is the percentage of flow that passes "straight" through the bypass chamber to the vaporizer outlet or the bypass chamber?
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more than 80%
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What is the percentage of flow from the flow meters that is diverted through the vaporizing chamber?
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less than 20%
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What is the vaporizer outlet?
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Where the vapor leaves the vaporizer.
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What are the components that leave the vaporizer?
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The combination of flow through the bypass chamber
Flow through the vaporizing chamber Flow of entrained anesthetic vapor. |
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What is the final concentration of inhaled anesthetic?
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The ratio of the flow of inhaled anesthetic to the total gas flow.
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What does the vapor pressure of inhaled anesthetic dependent on?
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Surrounding room temperature
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What is the vapor pressure when the ambient room temperature is high?
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Vapor pressure is high.
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How does the vaporizer compensate when the ambient room temperature is high? (Ohmeda)
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The bimettalic strip leans to the right which DECREASES THE RESISTANCE TO FLOW THROUGH THE BYPASS CHAMBER and ALLOWS MORE FRESH GAS TO PASS THROUGH THE BYPASS CHAMBER which DECREASES the flow through the vaporizing chamber.
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What happens to compensate for a decrease in vapor pressure during cold OR situations?
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The bimetallic strip leans to the left decreasing the flow through the bypass chamber and increases the flow through the vaporizing chamber.
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Which element directs a proportion of gas flow through the bypass chamber as temperature increases? (Drager)
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Expansion element
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At 20C VP for isoflurane is 238, what would happen if the temperature rises to 35C.
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The vapor pressure would almost double.
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When a fixed dial setting, vaporizer output can vary with the rate of gas flowing through the vaporizer True or False
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True
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Why is the output of all variable bypass vaporizers less than the dial setting in low flow rates (less than 250 ml/min).
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Because of the relatively high density of volatile inhaled anesthetics. Insufficient turbulence is generated in the vaporizing chamber at low flow rates to upwardly advance the vapor molecules.
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When there is extremely high flow rates such as 15 L per minute, the variable bypass vaporizers is ____ than the dial setting. This is due to?
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Less. The discrepancy is attributed to incomplete mixing and failure to saturate the carrier gas in the vaporizing chamber.
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The wick system are in direct contact with the metal wall of the vaporizer to help replace ______(____) consumed during vaporization.
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Energy(heat)
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Materials such as copper are selected for vaporizers why?
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High thermal conductivity and high specific heat. These factors minimize the effect of cooling during vaporization.
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Pumping effect is more pronounced in what? (3)
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Low flow rates
Low levels of liquid anesthetic Low dial settings |
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What can increase the pumping effect? (3)
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Rapid respiratory rates
High peak inspired pressures rapid drops in pressure during expiration |
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Newer variable bypass vaporizers are immune from pumping effect due to check valve between the ________ _____ and the ____ ____ ____. And what other feature helps prevent this?
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Vaporizer outlet and the common gas outlet.
The vaporizers are smaller. |
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What helps prevent filling a vaporizer with the wrong agent?
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Agent-specific, keyed filling devices
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Vaporizers are firmly secured to the manifold reducing the risk for what?
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Tipping of the vaporizer.
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What prevents the administration of more than one inhaled anesthetic?
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Contemporary interlock systems
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What agent is popular for induction of kids?
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Sevoflurane
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Which vaporizer is used for Desflurane?
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Datex-Ohmeda Tec 6
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Desflurane's vapor pressure is _-_ times that of other agents. MAC is _-_x higher than enflurane, isoflurane, and halothane.
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Vapor pressure is 3-4 times.
MAC is 4-9 x. |
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Desflurane has a low blood gas solubility coefficient which means that people recover from anesthesia faster or slower?
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Recovery from anesthesia is more rapid than other inhaled agents.
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In what year did the FDA approve Drager of its Tec 6 version?
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2004
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What is the only difference between the tec 6 and the tec 6 plus?
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Tec 6 plus has an enhanced audible alarm.
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How is the Tec 6 and Tec 6 plus different from other delivery vaporizers?
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There are two independent gas circuits that are arranged parallel.
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The Tec 6 and Tec 6 plus are the first vaporizers to be what?
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Electrically heated and pressurized
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Why does desflurane need a different vaporizer?
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It requires new systems to contain, transfer, and vaporize it.
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Trace the fresh gas flow through the tec 6.
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Fresh gas flows through the flow meters at the fresh gas inlet, then it passes through a fixed restrictor and exits at the vaporizer gas outlet.
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What is the desflurane sump's temperature controlled at? What does the sump serve as?
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39 C which is well above Desflurane's boiling point. It serves as a reservoir for the desflurane vapor.
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At 39 C the vapor pressure in the sump is about ____ mmHg absolute or about _ atm absolute.
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1300mmHg and 2 atm
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After the vaporizer warms up. the shut off valve full opens when the concentrating control valve is turned __.
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On
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A pressure regulating valve which is located downstream from the shut off valve down regulates the pressure to what and a FGF rate of __L/min?
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1.1 atm
FGF 10L/min |
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Operator controls the output of desflurane by adjusting the _____ ______ ______, a variable restrictor.
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Concentration control valve
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What equalizes the pressure between the FD circuit and the vapor circuit?
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The Control electronic system
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How is the FG flow and Vapor flow interfaced? (3)
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Differential pressure transducer
Control electronic system pressure regulating valve |
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When a constant FGF rate encounters the fixed restrictor R1, the FGF pushes against what?
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The diaphragm of the control differential pressure transducer.
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What is an electrically heated, thermostatically controlled, constant-temperature, pressurized, electromechanical coupled dual circuit, gas vapor blender?
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Tech vaporizer
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When the FGF rate increases the working pressure?
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Increases proportionally
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Given concentration setting even when varying the FGF rate, the vaporizer output is constant because....
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The amount of flow through each circuit remains proportional
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Why is the Datex-Ohmeda S/5 ADU unique?
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Single electronically controlled vaporizer designed to deliver 5 different anesthetics (halothane, isoflurane, enflurane, sevoflurane, AND desflurane). It provents retrograde flow of the vapor back into the bypass chamber.(which is crucial when delivering desflurane if room temp is higher than the boiling point).
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The DOA has a central processing unit, where does it receive its information?
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Concentration control dial
Pressure sensor inside the vaporizing chamber Temperature sensor inside the vaporizing chamber Flow measurement unit inside bypass chamber Flow measurement unit in the outlet of vaporizing chamber Flow Meters |
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What is in the bypass chamber that causes flow from the vaporizer inlet to split into two flow streams (bypass and vaporizing chambers)?
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Fixed Restrictor
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What is the DOA comprised of?
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Bypass chamber and vaporizing chamber.
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What type of vaporizer is the DOA?
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Variable bypass vaporizer
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During high FGF rates or dial settings or both what happens to the anesthetic liquid?
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Large amounts are vaporized rapidly
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What is the DOA equipped with to offset a cooling effect of late heat of vaporization?
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Warmed fan
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When is the fan activated? (2)
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Desflurane induction and maintenance
Sevoflurane induction |
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Vaporizers are sercured to AM in what?
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Manifolds
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User is prevented from delivering more than one agent simultaneously by what?
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Interlock system
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To fill, turn ___ vaporizers, check _____ _____ and ____ it in.
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Off
check correct agent pour it in |
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How do you find the percent of concentration??
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=VP agent/BPx100
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What is a breathing system (circuit)?
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A large bore corrugated hose that provides a flexible low resistance light weight connection from one part of the system to another.
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When the vaporizer exits the AM at the CGO, it enters the _____ _______.
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Breathing circuit
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Where does the breathing circuit begin and end?
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Extends from the Fresh gas inlet to the point at which gas escapes to the atmosphere or scavenging system but THE SCAVENGING SYSTEM IS NOT A PART OF THE BREATHING CIRCUIT.
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What are the 5 basic functions of the breathing system?
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Receives the gas mixture from the Anesthesia Machine
Delivers gas to the patient Removes CO2 and the conditions temperature and humidity of the inspired mixture Allows continuous flow from the AM to be converted into an intermittent flow Allows spontaneous, controlled, or assisted respirations, and provides for other functions such as gas sampling and air pressure, flow, and volume monitoring. |
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When were the first anesthetics administered?
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150 years ago
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Breathing Circuits
Type Reservoir Rebreathing Open |
Type Reservoir Rebreathing
Open No No |
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Type Reservoir Rebreathing
Semi-open |
Type Reservoir Rebreathing
Open Yes No |
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Type Reservoir Rebreathing
Semiclosed |
Type Reservoir Rebreathing
Semi-closed Yes Yes(partial) |
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Type Reservoir Rebreathing
Closed |
Type Reservoir Rebreathing
Closed YES Yes complete |
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Which system is the only system to has access to atmosphere?
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Open
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Fresh gas flow varies ________ with the amount of rebreathing. As the fresh gas flow increases the rebreathing in circuit _______.
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Inversely
Decreases |
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What type of system is one in which the exhaled gases containing carbon dioxide are removed from the system.
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Nonrebreathing systems
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What type of system is the inhalation of previous respired gases may or not have been removed?
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Rebreathing systems
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What is the volume in a breathing circuit occupied by gases that are rebreathed without any change in composition?
How can it be minimized? |
Mechanical (apparatus) dead space
By separating the inspiratory and expiratory gas streams as close to the patient as possible |
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What are the advantages of rebreathing?
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Increase in tracheal warmth and humidity and decrease in the potential for exposure of waste gases
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Rebreathing exhaled 02 has no effects but nitrogen _____ induction.
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Slows
N2 that is not eliminated from the circuit delays the establishment of the desired agent concentration therefore higher FGF is appropriate during induction |
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In contrast, rebreathing of exhaled agents during the maintenance phase is highly desirable for _____and _________ _______.
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Cost and environmental considerations
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Why do you want to avoid rebreathing CO2?
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Produces resipiratory acidosis
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Dead space is _______ to some degree with the use of any respiratory equipment. Rebreathing of exhaled CO2 is more ______. That is one reason why tidal volumes on a vent are larger than spontaneous respiration.
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Increased
likely |
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In a circle system the dead space ends at the __-_______.
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Y-piece
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What are advantages of using dry gases?
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To avoid internal corrosion and bacterial colonization.
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Active humidification is less common because?
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Less effective at preventing hypothermia
Added moisture can clog gas analysis line and soda lime granules or obstruct unidirectional valves |
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How do anesthetist passively humidify and heating inspired gases?
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With heat and moisture exchanger and by using low FGF.
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In the lungs, gases flow _____ their concentration gradients, interchanging between pulmonary and blood gases.
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Down
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In a non rebreathing circuit what is used for as a wash out?
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High FGF
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What are common features of nonrebreathing circuits?
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All lack unidirectional valves
All lack sode lime CO2 absorption Amount of resistance is low in ALL. Amount of rebreathing is highly dependent on the FGF in all. |
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In the mapleson system what are the designated letter and when was f introduced?
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A-F, F was added in 1975.
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What are the mapleson systems called sometimes?
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CO2 washout circuits or flow controlled breathing system.
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What are the 5 common components of the mapleson system?
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FACEMASK
SPRING-LOADED POP-OFF VALVE RESERVOIR TUBING FRESH GAS INFLOW TUBING RESERVOIR BAG |
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What are the three distinct functional groups
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A
BC DEF |
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Describe the Mapleson A or Magil circuit.
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Fresh gas flow enters at the opposite end of the circuit near the reservoir bag. There is a spring loaded pop-off valve located near the facemask. A corrugated tubing connects the bag to the adjustable pressure limiting valve at the end of the patient's system.
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During spontaneous ventilation what is the APL valve's position? What about when there is controlled or assisted ventilations?
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Fully open
when giving respirations the APL valve is partied closed so there is sufficient pressure to inflate the lungs. |
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What are the pro's and cons of the Mapleson A?
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It has the best efficiency of the 6 systems when spontaneous ventilation occurs but it has the WORST when CONTROLLED VENTILATION takes place.
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What FG flow rate is needed to prevent rebreathing in the mapleson A?
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one times the minute volume in spontaneous but may take up to 20L/min to prevent rebreathing.
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During spontaneous ventilation which mapleson systems are the best?
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A>D/F/E>C/B
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During controlled ventilation how is the mapleson system graded?
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D/F/E>B/C>A
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What is the main difference between the B/C mapelson compared to the mapelson A? What is the downfall of this system?
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The spring loaded Pop off valve is in the same spot by the mask but they fresh gas flow is now moved up to the mask area.
The reservoir tubing and breathing bag serve as blind limb where FG, dead space, and alveolar gas can collect. |
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During spontaneous ventilation (APL valve) and when are gases expelled?
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Fully open, gases are expelled during exhalation.
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During controlled ventilation (APL valve) and when are gases expelled?
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Significantly closed and during inhalation
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B and C are almost effective as A when expiratory pause is ______but less efficient when expiratory pause______.
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Minimal
increased |
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B and C FGF for spontanous
B and C FGF for controlled ventilation |
2 x minute volume
2-2.5 during controlled ventilation |
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What are the Mapleson D,E, and F referred to as?
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T-piece group
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What is different about the D,E, and F Mapleson?
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Fresh gas flow is up towards the mask, while the pop off valve is at the opposite end of the circuit.
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How is rebreathing eliminated with the Mapleson D?
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FG flows in pushing the expired air towards the other end of the circuit
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What are the pros of mapleson E
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Convenient switch between A and D/E arrangements.
Easy to preform IPPV |
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What is another name for mapleson F and what is the benefit?
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Jackson-Rees modification which was introduced in 1975. It offers very low resistance to breathing and can be used in any age. FGF should be at least 2-3 times to prevent rebreathing
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What are affecting factors CO2 rebreathing associated with the mapleson system?
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FG flow rate
Minute volume Tidal volume Respiratory rate CO2 sample site Duration of expiratory pause ventilation through ETT Ventilation through mask Peak inspiratory flow Duration of expiratory pause Inspirator to expiratory ratio Volume of breathing bag Volume of reservoir tube Mode of ventilation |
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What is the most popular nonrebreathing system in the united states and which mapleson system is it closest too?
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The bain circuit
Mapleson D |
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What are some benefits of using the bain system?
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Give inhaled gases greater heat and humidity
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What does the fresh gas flow need to be to prevent rebreathing?
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2.5 times minute ventilation
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What are the disadvantages of the bain system?
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The unrecognized kinking or disconnect of the hidden FG hose converts it into dead space.
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What is pethick's test?
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Detects fault inner tubes in the co-axial bain circle)
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What are the advantages of nonrebreathing systems?
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Lightweight
Convenient Easily sterilized Bain system may give heat and humidity of inhaled gas |
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What are the disadvantages of nonrebreathing systems?
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Pollution increased costs of agents and gases because of the need for higher flow
loss of heat from the patient bain system there are unrecognized kinks may need disconnected of FG supply hose and scavenger connection and may be reassemble improperly |
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What is the traditional breathing system referred to as?
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Universal F or single limb circuit
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How is the CO2 rebreathing prevented?
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Through CO2 absorbents but it allows rebreathing of other exhaled gases.
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What are the 7 Major components of the Traditional circle breathing system?
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Fresh gas flow source
Inspiratory and expiratory unidirectional valves Inspiratory and expiratory corrugate tubes (limbs) Y piece connector Overflow or apl valve Canister contain CO2 absorber |
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Traditional Circle Breathing System
To revent rebreathing of CO2, what are the THREE rules? |
Unidirectional valve must be located between the patient and the reservoir bag on both inspir and expir limbs.
FG inflow cannot enter the circuit between the patient and the expiratory valve. APL valve cannot be located between the patient and inspiratory valve |
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What are the advantages of the Circle system?
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constant inspired concentrations
conservation of respiratory tract heat and humidity minimal OR and enviromental pollution Uses for all APL valve positions Low resistance |
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What are the disadvantages of the Circle system?
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Relatively complex
Opportunites for misconnect or disconnect Malfunction of unidirectional flows can cause serious problem Less portable than nobreathing Increased dead space |
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What are causes of circle system obstruction?
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Manufacturing defects
Debris Patient secretions Particulate obstruction from other odd sources such as albuterol nebulization |
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In flows such as ___L/min to ____L/min total rebreathing and full reliance is on the absorbent.
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0.3 to 0.5
High flows are not reliant on the co2 absorber |
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What are two commonly used absorbants?
|
SODA LIME
CALCIUM HYDROXIDE LIME |
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What is the composition of high moisture soda lime?
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80% Calcium hydroxide
15% water 4% sodium hydroxide 1% potassium hydroxide |
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What is the catalyst for CO2 absorptive properties?
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Sodium hydroxide
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What are the factors of producing compound A with use of sevoflurane?
|
Low-flow or closed circuit anesthesia techniques
use of baralyme rather than sode lime high absorbent temperatures fresh absorbent high sevoflurane in the anesthestic circuit YOU CAN ONLY USE FLOW RATES OF 2L or less for 2 HOURS with THE USE OF SEVOFLURANE |
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What is compound A harmful too?
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Kidneys
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Smaller the granule, the _______the surface area available for absorption. As particular size decreases, airflow resistance _______.
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greater
increases |
