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202 Cards in this Set
- Front
- Back
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SPDD model
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The path of the gases followed from arrival to OR to disposal from OR.
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What does SPDD stand for?
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Supply, Processing, Delivery, and Disposal
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(Pipeline Supply)
Oxygen is produced by : |
the fractional distillation of liquid air.
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Oxygen is stored as a liquid at
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184 degrees C.
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O2 is supplied to hospital pipelines at
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50 psi (344 kPa)
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N2O is delivered to the hospital in large size __ cylinders
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H cylinders
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Couplers are used to connect _____ to _____
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connect gas-machine hoses TO wall outlets
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Delivery piping for both N20 and O2 use the ___ to prevent ___
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DISS to prevent misconnections
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At pipeline inlet, what 3 things are present?
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a filter, check valve, and pressure gauge are present.
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a. Check valve ensures:
b. A Filter is required to prevent |
a. unidirectional flow
b. prevent particulate matter present in the pipeline gas |
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O2 is contained in ___ cylinders
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E cylinders
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Optimal management of loss of O2 pipeline pressure has these 4 goals:
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a. Maintenance of oxygenation
b. Ventilation c. Depth of anesthesia d. Ensuring safety of o2 supply |
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If E cylinder not completely closed & pipeline fails, what will happen?
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O2 will flow from the cylinder back to the pipeline in a retrograde fashion.
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What would happen in cross-connection occurred
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Would see a decline in inspired o2 concentration
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How can cross-connection occur?
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If gas placed in wrong vaporizer
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In the event of a suspected crossover, what should you do?
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a. Open emergency o2 cylinder
b. Disconnect the pipeline c. Consider using low fresh gas flows & manual ventilation. |
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If the pipeline is not disconnected, what will happen?
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It will continue to flow due to the differences in the pipeline pressure
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What is the difference (or psi of) in Pipeline pressure vs. Cylinder pressure?
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Pipeline pressure = (50 psi)
Cylinder pressure = (45 psi) |
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What is the safety mechanism for the gas cylinders?
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PISS
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o2 (color, psi, L, & pin position)
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Green
1900 psi 660 Liters 2-5 in the pin position |
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N2o (color, psi, L, & pin position)
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Blue
745 psi 1590 L 3-5 in the pin position |
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Air (color, psi, L, & pin position)
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Yellow
1900 psi 625 L 1-5 in the pin position |
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What is the most fragile part of the cylinder?
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The cylinder valve.
Must be protected during transport. |
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What will happen if the cylinder is exposed to a fire?
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The temp & press will increase, but safety relief devises release cylinder contents in a controlled fashion.
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What 3 things may happen in response to the cylinder being exposed to fire?
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1. A frangible disk bursts under pressure
2. Or a valve will open @ extreme pressure 3. Or a fusible plug made of Wood’s metal will melt |
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What 4 things are Wood's metal made out of?
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bismuth, lead, tin, & cadmium
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HIGH Pressure System Components: (4)
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1. Hangar yoke
2. Yoke block with check valves 3. Cylinder pressure gauge 4. Cylinder pressure regulators |
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INTERMEDIATE Pressure System Components: (6)
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1. Pipeline inlets, check valves & pressure gauges
2. Ventilator power inlet 3. O2 pressure-failure devices 4. Flowmeter valve 5. O2 second-stage regulator 6. Flush valve |
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LOW Pressure System Components: (4)
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1. Flowmeter tubes
2. Vaporizers 3. Check valves 4. Common gas outlet |
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3 Functions of the hanger yolk:
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1. Provides gas-tight seal
2. Ensures unidirectional flow 3. Orients cylinders |
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Transfilling is a potential...
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Fire hazard because it generates heat
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Pressure gauge is a bourdon-type gauge that indicates...
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pressure within whichever of the cylinders for the same gas has the higher pressure
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Immediately distal to the hangar yoke for each gas is a____ which does what?
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regulator
1. The regulator converts high cylinder pressure to a constant downstream pressure of 45 psi |
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U.S. Department of Transportation issues regulations for the ____,____,____, & ____ of ______
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manufacture, handling, transport, storage, and disposal of cylinders.
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What type of cylinders may be used in an MRI environment?
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Only nonferrous (aluminum) cylinders
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Equation for calculating how long the cylinder will last:
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Capacity Ltr's = Contents Left
Service pres psi = Gauge pres psi |
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The contents of the cylinders are regulated by:
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the FDA
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U.S Pharmacopeia sets standards for the _____ for medical gases
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purity standards
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Nitrous Oxide pressure gauge stays at ___ psi until ___ at that point the cylinder is more than___
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- 745 psi until the liquid is gone.
- Three quarters empty. |
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Change the N2O cylinders if: (1)
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It is below 745 psi.
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N2O is Flammable - or-nonflammable? and it supports ___
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Nonflammable but supports combustion.
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Required monitors : (6)
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1. Inspired O2
2. Exhaled volume 3. O2 supply failure alarm 4. Hypoxic guard system 5. Anesthetic vapor concentr... 6. Pulse ox., BP, and ETCo2 |
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All gases except __ pass through a fail-safe valve before proceeding to their flow meters.
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oxygen
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This fail-safe valve is held open by ____ in the ____ circuitry.
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pressure in the oxygen
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O2 always added to the common manifold _____ of other gases. Why?
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1. downstream
2. so that the chance of hypoxic breathing mixtures is lessened |
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An amt. equal to the fresh gas flow per minute (minus ___ , plus _____) leaves the breathing circuit and is conducted to the ___
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1. fresh gas flow/minute
2. (-)pt uptake, (+)gases excreted 3. scavenger interface |
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Five Tasks of o2:
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1. Proceeds to the FGF meter
2. Powers the oxygen flush 3. Activates fail-safe mechs 4. Activates oxygen low-pressure alarms 5. Compresses bellows |
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Glass flow tube is called a:
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Thorpe tube.
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The indicator float in the glass flow tube designed to...
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capture and display the FGF.
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O2 flow meters are calibrated to ___ accuracy at ___ temp & ___ kPa
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1. 5%
2. room 3. 101.3 kpa |
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Flow tube is narrower at the ____ so it may be referred to as a "____ ____" flow meter.
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1. bottom
2. variable orifice flow meter |
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What's the most fragile part of the anesthesia machine?
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flow meters
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Oxygen flush deliver o2 @ __ - __L/min
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35 to 75 L/min
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Purpose of the o2 flush
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to quickly fill the circuit with o2, which can dilute the gases in the circuit
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Increased risk of barotrauma can result if o2 flush...
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pushed accidently during inspiration phase.
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Fail-Safe Systems protect ____
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the patient from receiving a hypoxic mixture.
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What is one major standard of the fail-safe system?
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that the set concentration of o2 at the CGO doesn’t decline if the pipeline pressure decreases.
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Low-Pressure Alarms do what? at what psi?
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Signals the operator when pressure is lost in the o2 circuitry. It signals @ 28 psi & below.
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Ventilator Driving Gas
(2) |
1. o2 compresses the ventilator bellows in most machines
2. Use electric motors in newer models therefore it isn't dependent on O2 pipeline pressure. |
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Proportioning Systems (hypoxic guard)
1. At least need __-__% O2 w/ N2O (_:_ ratio) 2. Remember... |
1. At least need 23-25% o2 w/ N2o (3:1 ratio)
2. This isn't a fool proof system |
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Only 1 system ensures that O2 is being administered through the pipeline and that is:
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inspired oxygen analysis
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Vapor is composed of molecules of a substance that is liquid at ___ temp and _ atm of pressure
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room temp and 1 atm of pressure
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As evaporation proceeds, the remaining liquid cools. Why?
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because heat energy is carried away from the liquid
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What metal is chosen to be used in vaporizers...why? (3)
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Copper.
B/c: it prevents latent phase of vaporization, has a high thermal capacity, & high thermal conductivity. |
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Rate of vaporization depends on: (3)
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1. temperature
2. vapor pressure of the liquids 3. partial pressure of the vapor above the evaporating liquid. |
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How does Variable Bypass limit vapor output to clinically useful concentration?
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Only allows a small amount of FGF to come in contact with liquid anesthetic
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Variable Bypass splitting ratio is determined by the...
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by the internal resistance to flow
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How do you increase flow to the vaporizing chamber in a Variable Bypass machine?
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By increasing the dial concentrations
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What is the function of "wicks" and "baffles" in the Variable Bypass?
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They ensure full saturation of the carrier gas
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The concentration of carrier gas is diluted where and with what (in variable bypass)?
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It's diluted at the vaporizing chamber outlet with FGF that bypassed the vaporizing chamber
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Why can't Des be in a normal vaporizing chamber in the Variable Bypass?
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Bc at room temp, it can cause hypoxic mixtures
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Why is a temperature compensation device is built into the variable bypass vaporizers
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So that more gas is directed into the vaporizing chambers as the vaporizer cools
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How is a "Measured Flow Vaporizer (Vernitrol)" operated?
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The operator determines how much gas should be bubbled through the anesthetic liquid by a formula
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With a "Measured Flow Vaporizer (Vernitrol)," what needs to be done if the vaporizer cools?
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new formulas must be determined. (manual temp. compensation).
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Tec 6 Injector is a
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Heated, dual-circuit vaporizer
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How does the 1st circuit of the Tec 6 Injector work?
(2 steps) |
1. FGF passes through vaporizer in 1 circuit (never in contact with the liquid agent).
2. Vapor is then added to the FGF. |
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How does the 2nd circuit of the Tec 6 Injector work?
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The 2nd circuit has 2 control points:
- a concentration control dial and - a transducer that is responsive to the amt of FGF. |
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What agent can be added to a Tec 6 vaporizer?
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Desflurane
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Des is near boiling point near what temperature?
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Room temp
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What kind of system is in place to prevent more than 1 gas to be administered at a time?
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Interlock system
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What mechanism is in place to prevent the chance of filling a vaporizer with the wrong agent?
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Keyed filler mechanism
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Why should you not overfill your vaporizers?
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b/c it can result in d/c of the liquid anesthetic from the vaporizer outlet that can lead to patient injury
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Why is tipping hazardous?
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b/c the entry of liquid agent into the control assembly at the top of the vaporizer can have unpredictable effects on its fxn.
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What are the most common reasons for vaporizer leaks?
(4) |
1. malposition
2. accidental dislodgement 3. loss of gaskets 4. mechanical damage. |
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Overpressure can be combined with low flows, but 18% of 2 L contains ___desflurane molecules than 18% of 6 L
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fewer
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Why shouldn't you institute low gas flows too early?
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Because it will prolong induction
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"wash in" is based on the concept of a...
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time constant
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-One time constant brings system to ___% of the way to equilibrium
- Two time constants to___% - Three time constants to ___% |
1 = 63%
2= 86% 3= 95% |
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What is the purpose of the breathing circuit
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delivery of O2 and anesthetic and the elimination of CO2.
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CO2 is eliminated by? (3)
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1. washout
2. adequate fresh gas flow 3. absorption into CO2 absorbent granules. |
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How do you minimize resistance in the circuit? (5)
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1. reducing the length
2. increasing its diameter 3. avoid the use of sharp bends 4. eliminating valves 5. maintain laminar flow |
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What happens when exhaled nitrogen that isn't eliminated from the breathing circuit is rebreathed?
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it delays the establishment of the desired agent concentration.
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How do you prevent/decrease the rebreathing of exhaled nitrogen?
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Use high FGF during induction
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The rebreathing of Co2 causes what undesirable pt outcome?
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Respiratory acidosis
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Why are tidal volumes set higher than a normal spontaneous breath?
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To compensate for dead space ventilation
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Alveolar ventilation is determined by what equation?
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= min.vent - dead space
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If the patient's min vent is fixed, increasing dead space ___es alveolar ventilation and ___es arterial Co2 tension
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decreases, increases
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Why are dry gasses used for the anesthesia machines?
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So that the problems of internal corrosion and bacterial colonization are avoided.
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What type of breathing system allows pts to have access to atmosphere?
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open systems
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In non-breathing circuits, if FGF is sufficient, then
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no alveolar gas is rebreathed
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Factoids about non-breathing circuits (4)
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a. lacks unidirectional valves
b. lack soda lime CO2 absorption c. Amt of rebreathing highly dependent on FGF d. Amt of resistance is low in all -good for kids to adults |
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Examples of non-breathing circuits (3)
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1. Mapleson D
2. Mapelson F 3. Brain system |
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What is one feature of the "brain system?"
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Has FG hose directed coaxially within the corrugated limb. Giving inhaled gases heat & humidity
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What happens if the "brain circuit" get kincked?
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It turns the whole hose into dead space and can cause respiratory acidosis.
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The brain circuit can be used for which weight range?
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children at least 10-20kg
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Brain system advantages (4)
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Advantage: lightweight, convenient, easily sterilized and scavenged
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Brain system disadvantages (3)
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1. unrecognized disconnection can cause respiratory acidosis
2. need higher FGF 3. loss of heat from patient. |
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Where does gas enter and exit the circle system?
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ENTERS the breathing circuit from the common gas outlet by way of the FG delivery hose, & EXITS the circle via the APL valve
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What is the function of the APL valve?
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It creates an adjustable leak during manual ventilation
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Whats the function of the unidirectional valves?
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valves enforce a pattern of gas flow by which exhalations are made to pass through the CO2 absorbent
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There are only 2 common reasons for an increase in inspired CO2
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1. absorbent granules have been exhausted
2. unidirectional valves are faulty |
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What should you do if inspired CO2 of more than 1-3 mmHg is detected on the capnograph?
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the FGF should be increased to 5-8 L/min
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Why should you increase the FGF to 5-8L if >1-3 insp Co2 detected?
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this converts the system to a semi-open configuration in which rebreathing of exhaled gases is minimized.
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Circle System advantages (4)
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1. constant inspired concentration
2.conserve of resp heat &humidity 3. min. OR & environmental pollution 4. low resistance |
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Circle systems are useful for which types of systems? (3)
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1. closed -system
2. low-flow 3. semi-open configurations. |
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Circle system disadvantages (2)
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1. complex
2. malfxng unidirectional valves |
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Open unidirectional valves cause:
Closed unidirectional valves cause: |
Open: rebreathing
Closed: occlusion, less portable, increased dead space. |
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What is the diameter of breathing hoses? is it the same size as the scavenger hose?
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1. 22mm
2. no |
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What is the equation for measuring how quickly a breathing system reaches equilibrium
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time constant= capacity / flow
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What happens if flows are substantially HIGHER than minute ventilation
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Each breath reflects the dialed concentration of the agent dialed due to no rebreathing of exhaled gases
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What types of patients are LOW flows contraindicated in? (3)
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1. smoke inhalation injury
2. malignant hyperthermia 3. when washout of dangerous gases or a high O2 uptake is expected. |
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Relative contraindications of HIGH flows include:(4)
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1. when using older equipment that is less leak proof
2. face mask anesthesia 3. during rigid bronchoscopy 4. uncuffed endotracheal tubes. |
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What are 2 advantages for use of HMEF's?
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1. prevent nosocomial infections
2. good for humidification. |
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Co2 absorbers do what? (2)
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1. Makes rebreathing of exhalations possible
2.Conserves gases, agent & humidity while preventing acidosis. |
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A circle system with FGF of 0.3-0.5 L/min provides what?
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near-total rebreathing & full reliance on absorbent for prevention of rebreathing of CO2.
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What should you do if you have hypercarbia associated with absorbent exhaustion?
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Increase FGFs
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CO2 + H2O ↔
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H2CO3
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H2CO3 + NaOH (or KOH) ↔
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Na2CO3 (or K2CO3) + H20 + energy
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Na2CO3 (or K2CO3) + Ca(OH)2 →
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CaCO3 ↓ + NaOH (or KOH)
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Why is an appropriate water content (10-20%) important?
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For speed & efficiency of the reactions. Dry granules become exhausted faster.
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Absorption of 1 mole of CO2 produces ____ kcal of _____
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13,000 kcal of heat energy
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What is the name of the additive in absorbents that changes colors when exhausted?
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Ethyl violet
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At what pH does ethyl violet change from colorless to blue/purple?
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pH of 10.3
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What is soda lime mainly made out of?
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calcium hydroxide
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What is the water content of soda lime?
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13-20%
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How large are the soda lime granules? what does that mean?
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1. 4-8 mesh
2. they will pass through screens with 4-8 holes per linear inch. |
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Selection of granule size involves a compromise between ____ and ______.
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1. resistance to flow
2. absorption efficiency |
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What agent is degraded the most and which the least?
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1. Sevo (most)
2. Des (least) |
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Sevo may be degraded so much at low flows in desiccated barium hydroxide lime. What is the problem with that?
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It is impossible to attain 1 MAC in the breathing circuit, regardless of the dial setting.
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Sevo produces compound A and it is lethal at ___ ppm, and may cause renal injury at ___ ppm in rats.
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1. 130-340 ppm
2. 25-50 ppm |
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Not recommended to run sevo at total FGF less than ___ for more than____
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1-2 L/min for more than 2 MAC-hours
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CO is produced by ___ much more than ___ when these agents are in contact with absorbent granules.
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desflurane
iso |
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What bases are implicated in CO problems with ethyl methyl ethers?
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Strong bases (the activators NaOH, and particularly KOH)
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What is another benefit of Co2 absorbers?
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Works as a trap for water and dust that prevents the passage of dust toward the patient
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In the Co2 absorber...where is the lowest resistance pathway?
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the outer edge
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If granules do become exhausted, a safer alternative strategy is to...
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change FGF to one to two times the minute ventilation.
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Each 100 g of granules can absorb as much as __L of CO2 before the outlet concentration is 1%.
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15 L of Co2
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What is the average to maximum production of Co2 by the anesthetized adult?
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12-18L/hr
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With total rebreathing the top canister might last approx. ___ hours.
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8-10hrs
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Ethyl violet may become inactivated by ___ or ___
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gas flows or intense light around the wall of the canister
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What will cause a more rapid dehydration of the granules? (2)
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1. If higher FGF are used
2. Excessively flushing o2 |
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What type of bellows contains the gas inspired & expired by the patient & separates it from the surrounding driving gas.
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Gas-Driven Bellows
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What occurs during the inspiratory phase of the gas-driven bellows?
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The driving gas closes this relief valve, preventing gas within the bellows from exiting to the scavenger as the bellows are compressed
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What does the ventilator relief valve do in a gas driven bellows?
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Buildup of volume and pressure within the breathing circuit is prevented by a ventilator relief valve that remains open during expiratory phase.
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How much PEEP is maintained with in the gas driven bellows circuit?
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2-3cm water of PEEP
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What doesn't occur in the event of disconnect when using a standing bellows?
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The bellows wont fill
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Theory of Operation-Piston Driven Ventilators
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a. No driving gases utilized so they may be used without depleting the O2 cylinder in case of O2 pipeline failure.
b. (+) and (-) pressure relief valves built in. |
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Operation-Piston Driven Ventilators have was unique feature built in?
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+ and - pressure valves
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What happens if the piston pressure reaches +75 or falls to -8cm in a Piston Driven Ventilator?
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- If +75, then pressure relief valve opens
- If -8, then pressure relief valve opens? |
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Advantages of Piston Driven Ventilator? (4)
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1. quiet
2. no PEEP in the circuit 3.precision in delivered tidal volume 4. fewer compliance losses |
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How does Volume Controlled Ventilation work? (2)
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1. Desired tidal volume (VT) is set & delivered at a constant rate.
2. Volume limited, time cycled, and constant flow |
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What is one aspect of using volume controlled ventilation that is not controlled?
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Peak inspiratory pressure is uncontrolled & varies according to compliance & airway resistance.
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Typical initial settings in adult w/ a VCV are: VT __mL/kg, RR _-_ breaths/min, PEEP__cm H2O, & I:E ratio _:_.
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VT: 10 mL/kg
RR: 6-12 breaths/min PEEP: 0 cm H2O I:E ratio 1:2. |
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How does Pressure Controlled Ventilation work? (2)
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a. Insp pressure controlled rather than volume.
b. Insp volume varies w/ changes in compliance & airway resistance |
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One risk when using PCV with patients with low compliance?
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PCV may produce higher tidal volumes than VCV.
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When using PCV, what should you do initially and then change?
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High flow needed at first, and less flow is required to maintain this pressure
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Typical PCV initial settings: Pressure limit __cm H2O, RR _-_ breaths/min, PEEP _cm H2O, I:E _:_.
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Pressure limit 20cm H2O
RR 6-12 breaths/min PEEP 0 cm H2O I:E 1:2. |
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How does SIMV run?
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Like VCV, it is VC'd ventilation, but the intermittent mandatory breaths are delivered in synchrony with, & triggered by, the pt’s spontaneous efforts.
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How doe SIMV work?
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Works off of a trigger window
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How can SIMV be used?
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Can be used for full to partial ventilatory support.
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How does Pressure-Support Ventilation (PSV) work?
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a. Like PCV, but with a RR of 0.
b. Responsive to the pt’s efforts, & delivers a breath within a trigger window. |
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Who is PSV good to use with?
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Useful for patients who are breathing spontaneously
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Primary settings for PSV
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1. No minimum minute ventilation
2. 1* setting is the PS level, w/adults can start at 10 cm H2O. |
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What is a good alternative for pts who can't tolerate VCV?
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PCV
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Which two vent modes are good for getting pts back in spontaneously breathing?
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SIMV & PSV
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What 2 machine checks should be done b/n cases?
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Electronic leak & compliance test is part of the morning checklist, & must be repeated b/n cases
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What is one perk of newer ventilators in relation to TV and FGF?
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Newer ventilators compensate delivered tidal volume for changes in fresh gas flow.
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What are some advantages to low FGFs? (4)
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1. reduce pollution, cost of volatile agents & N2O
2. preserve tracheal heat & moisture 3. prevent soda lime from drying 4. help preserve pt body temp. |
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What is the most common preventable equipment-related cause of mishaps?
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Failure to ventilate caused by disconnection
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Where is the most common site for disconnect?
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B/n the breathing circuit & the ETT.
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What is the 1* monitor for disconnect? (3)
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continuous auscultation of breath sounds w/ a precordial or esophageal stethoscope, as well as direct visual observation of chest movement.
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What can cause high pressure alarm (7)
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Occlusion, bellows leaks, failure of gas supply, failure of the ventilator relief valve, inadvertent application of suction to the airway, failure to remove plastic wrap from soda lime canister, insertion of occluded disposable PEEP
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What should you do if you have a high pressure alarm?
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Assess the pt for bronchospasm
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If circuit pressure is sustained during manual ventilation with the circuit, it is likely that...
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The scavenger is obstructed or relief valves have failed.
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What should you do if MH is suspected? (4)
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1. Stop using the triggering agent
2. Hyperventilate w/ o2 100% 3. increase FGF 4. change the breathing circuit components & granules |
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What should you do if you are planning to administer anesthesia to a pt with a HX of MH
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Change the breathing circuit & granules, disable the vaporizers, and flush the machine at a rate of 10L for 20min
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What is the fxn of the scavenging system?
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Collection of waste anesthetic gases from the breathing circuit & ventilator, and their removal from the OR.
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How much is scavenged per minute?
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An amount = to the FGF rate
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Who publishes a standard for exposure to anesthetic waste?
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OSHA
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What is the max allowable exposure to halogenated agents, N2o, and Halothane?
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Halogentaed: 2ppm (0.5 is w/ N20)
N2o: 25ppm Halothane: 85ppm |
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Is there any proof that chronic exposure to volatile agents?
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No, but N2o should definitely be avoided
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What is the most important part of the scavenging system?
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The interface, b/c it protects the pt from excessive buildup of + pressure & from exposure to suction
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When in closed interface useful?
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Where passive scavenging is used
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How does closed interface communicate to the atmosphere? What does that mean?
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- Only through valves.
- Therefore a means for relief of + pressure is mandatory for all closed interfaces. |
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What happens if a closed interface is attached to suction?
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(-) pressure relief valve opens to draw in room air when suction is excessive to prevent emptying of gas from circuit
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How does open interface work?
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Has large open holes or ports around the top. No valves to impede flow.
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What will notify you if a closed interface is leaking gas?
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you will hear soft intermittent hiss
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How do you know if an open interface is working correctly?
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You will hear a continuous hissing sound
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Definition of Department-Level aspects:
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A detection system designed to predict failures & ensure that precautions to prevent pt harm are taken.
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What does the The Safe Medical Device Act of 1990 require? (3)
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1. That hospitals report instances where medical devices cause or contribute to death, serious illness, or serious injury.
2. Results must be reported to FDA within 10 working days if medical devices cause problems. 3. Equipment should be sequestered if it is thought to be a cause of injury in a patient. |
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What is the most effective test for leaks in the low-pressure system?
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Negative-Pressure test
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Leaks in the low pressure system can lead to: (2)
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1. Hypoxic breathing mixtures
2. Awareness under anesthesia. |
