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Anesthesia > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

How are ventilators classified?

A

By inspiratory flow characteristics
There are 3 types: constant flow, non-constant flow, and constant pressure generators

Also by method of cycling (volume, pressure, or time cycled)

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2
Q

4 Divisions of the breathing cycle

A

4 divisions: inspiration, transition from insp to exp, expiration, and transition from exp to insp

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3
Q

Can you give PPV with an LMA?

A

Yes, but you could end up putting a lot of air in their stomach

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4
Q

How often should the anesthesia machine be powered down?

A

Every 24 hours

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5
Q

Organization that sets standards for anesthesia machines from 2000, forward

A

American Society for Testing and Materials (ASTM)

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6
Q

Organization that set standards for anesthesia machines prior to 2000

A

American National Standards Institute (ANSI)

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7
Q

Control that enables you to switch between mechanical and manual ventilation

A

Selector switch

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8
Q

Why is it bad to pressure the O2 flush valve while connected to the patient?

A

It delivers 35-75L/min and exposes the patient to 45-55 psi of pressure, resulting in a potential for barotrauma (especially during inhalation). Cases of awareness have been reported as well.

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9
Q

5 Components of Semi-Open Systems

A

1) Facemask
2) Pop-off valve
3) Reservoir Tubing
4) Fresh Gas Inlet
5) Reservoir Bag

The Mapleson Systems are examples of semi-open systems

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10
Q

Characteristic shared by Mapleson A, B and C

A

Pop-of valve (APL valve) is close to the patient

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11
Q

Extent of CO2 rebreathing with a Mapleson system will depend on _______

A

Minute ventilation, fresh gas flow, breathing pattern, and if the ventilation is manual or spontaneous.

CO2 rebreathing is a big concern for the semi-open system, because there is no separate inspiratory and expiratory limb

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12
Q

Mapleson configuration that is best for controlled ventilation

A

Mapleson D is best for controlled ventilation (however, the system can be used for controlled OR spontaneous). The Mapleson D is the reversed configuration of Mapleson A

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13
Q

Benefits of the Bain circuit

A

Adds more heat and humidity than the other Mapleson circuits. Uses the same rate of FGF as Mapleson D.

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14
Q

FGF requirements for Mapleson D

A

2-3 x MV if spontaneous
1-2 x MV if controlled
Why is this different? Because you get a longer expiratory pause with controlled ventilation.

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15
Q

Mapleson configuration that is missing a reservoir bag and pop-off valve

A

Mapleson E

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16
Q

Ways to decrease CO2 rebreathing in Mapleson systems

A

High FGF, low TV, and long expiratory pause

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17
Q

Unique hazard of the Bain circuit

A

Disconnection or kinking of the inner tube

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18
Q

The bain circuit is a modification of what Mapleson?

A

It is a co-axial modification of Mapleson D

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19
Q

Advantages of the Mapleson System

A

Simple components, lightweight, portable, low resistance (because no unidirectional valves or CO2 absorber), can give PPV, more predictable anesthetic concentration, and decreased rom pollution

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20
Q

Disadvantages of the Mapleson System

A

1) You have to calculate FGF, which varies with type of circuit and mode of ventilation
2) Control of anesthetic depth is variable. Agents are diluted as FGF increases.
3) CO2 buildup con occur if FGF not high enough
4) Minimal rebreathing of gases other than CO2- results in high cost and poor conservation of heat and humidity
5) Requires special assembly and the function is complex

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21
Q

The Mapleson E is a modification of what?

A

Eyre’s T-Piece, which is often used to give O2 in the ICU and PACU

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22
Q

Common characteristic of Mapleson D, E, and F

A

The FGF is the closest thing to the patient

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23
Q

Mapleson system that is best for spontaneous ventilation

A

Mapleson A. This system, however, is the worst for controlled ventilation.

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24
Q

How common is use of the various Mapleson systems?

A

A, B, and C are not used all that much, but D, E, and F are still frequently used. In the US, the Bain circuit is the most popular from the DEF group.

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25
Q

Mapleson circuit best for eliminating expired CO2

A

Bain circuit, because the FGF is aimed directly down the ET tube, which reduces dead space.

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26
Q

Describe the Mapleson F system

A

This is also known as the Jackson-Rees system, which is a modification of Mapleson E. Basically, it is Mapleson E with a APL valve at the end of the reservoir bag. This is a very popular system in pediatrics because there are no moving parts except the APL valve, and there is minimum dead space and resistance.

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27
Q

Most commonly used anesthetic breathing systems

A

1) Mapleson F (Jackson-Rees)
2) Bain Circuit
3) Circle System

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28
Q

The ambu bag is a modified Mapleson __

A

A

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29
Q

Disadvantages of ambu bags

A

Requires high FGF and the reservoir is self-filling. A self inflating bag is heavier and gives you less tactile information about ventilation.

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30
Q

What does the term insufflation refer to?

A

The act of inhaling a substance

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31
Q

Formula for normal TV

A

4-6mL/kg of ideal body weight

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32
Q

Back-pressure in the vent can come from ____

A

The patient’s airway resistance and lung/thorax compliance

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33
Q

Where is flow rate calculated?

A

From the connection of the breathing system to the patient

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34
Q

3 types of inspiratory characteristics

A

Constant flow, non-constant flow, and constant pressure

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35
Q

4 Methods of cycling

A

Time, volume, pressure, and flow

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36
Q

Time Cycling

A

You set the time for the I:E ratio. Cycle to the exp phase once the predetermined interval elapses from the start of inspiration.

In this case, TV is a product of the set insp time and insp flow rate

Most of our vents are time cycled***** This is electronically controlled with a volume limiting aspect. There is a set inspiratory time, but the volume given can not go over a certain value.

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37
Q

Volume Cycling

A

Inspiration terminates once the predetermined TV is delivered. There is also a limit on inspiratory pressure to protect against barotrauma.

A percentage of the TV is always lost to compliance of the system (about 4-5cc/cmH20)

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38
Q

Pressure Cycling

A

Cycle into the exp phase once a predetermined airway pressure has been reached for a certain amount of time. TV and insp time will vary.

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39
Q

Flow Cycling

A

Pressure and flow sensors allow the vent to monitor inp flow at a preselected, fixed, insp pressure. Once the flow reaches that level (at the set pressure), the vent will cycle to expiration

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40
Q

How much volume per kg do we give during PPV?

A

about 10-15cc/kg of ideal body weight

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41
Q

Double-Citcuit Bellows

A

The bellows are compressed by a driving gas and pneumatically driven (the gas takes a DOUBLE circuit- some goes to the patient, and some goes to drive the bellows)

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42
Q

Piston-Bellows

A

Compressed by electricity

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43
Q

What is the driving gas?

A

The gas that compresses the bellows

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44
Q

Is the vent relief valve open during inspiration or expiration?

A

It is ONLY open during expiration, and any scavenging occurs at this point.

Exhaled gases from the patient first fill the bellows (because the valve ball produces 2-3cmH20 of back pressure). Any excess pressure after the bellows are filled will go to scavenge.

On inspiration, the pressure relief valve closes, the the contents of the bellows are delivered to the patient.

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45
Q

Do piston ventilators have bellows?

A

No. There is no driving gas. Electricity is used to power the vent

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46
Q

Three modes of controlled ventilation in anesthesia vents

A

Volume control, SIMV, and pressure control

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47
Q

Inspiratory pause / sigh

A

Inhalation time is increased by 25%. During this time, the volume of gas is held in the lungs to hopefully recruit more alveoli. This extra time detracts time from the expiratory phase.

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48
Q

Relationship between PaCO2 and end tidal CO2

A

End tidal is usually 5 less than the true PaCO2

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49
Q

Typical TV and RR set on the vent

A

10-15cc/kg and 8-12 breaths/min

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50
Q

What is the normal physiologic I:E ratio?

A

1:2

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51
Q

Normal flow rate for the vent

A

4-6 x the MV. This is how fast and how much gas is driving the bellows. Without adequate flow, the vent will not work.

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52
Q

Formula for inspiratory time

A

Ti = TV / Flow rate

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53
Q

How does hypoventilation affect PaO2?

A

It decreases

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54
Q

Increasing FiO2 by 10% will increase PaO2 by _____

A

50mmHg

For reference:
FiO2 of 21% is PaO2 of 100mmHg
30% --------> 150mmHg
40% --------> 200mmHg
Etc.
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55
Q

A sustained pressure alarm will be triggered if ______

A

System pressure has been 15cm H2O for more than 10 seconds

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56
Q

High peak pressure alarm is triggered if ______

A

pressure in the system reaches 60cm H2O

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57
Q

Subatmospheric pressure is triggered at a pressure of ______

A

-10 cmH2O

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58
Q

Do ICU vents have a CO2 absorber?

A

No

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59
Q

Volume that will be measured by the respirometer

A

TV + FGF + volume lost in system

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60
Q

Most common vent mode in the OR

A

Volume Control (VC)

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61
Q

Volume Control Characteristics

A

Provider sets TV and RR, and these are delivered to the pt, independent of pt effort.

Time initiated, volume limited, and cycled by volume or time (depending on machine type)

Flow rate is fixed during inspiration. Won’t work if too low. If too high, can cause insp pauses or high peak pressures.

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62
Q

Pressure Control Characteristics

A

Provider sets inspiratory pressure

Gas flow decreases as a/w pressures rise, and flow stops once the set peak pressure is reached.

TV is not fixed. It depends on rise time and set pressure.

Increasing the inspiratory rate will shorten time and volume.

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63
Q

When is Pressure Control used?

A

In situations where pressures can be high. Often helpful in neonates and premature infants.

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64
Q

What vent mode is used when a patient is waking up from anesthesia?

A

SIMV

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65
Q

What size are the tidal volumes in high frequency ventilation?

A

Small. Often less than dead space.

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66
Q

How much TV is usually lost due to compliance of the system?

A

About 4-5cc / cmH2O

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67
Q

Do piston ventilators use a driving gas?

A

No. No bellows, no driving gas.

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68
Q

Advantages of piston ventilators

A

Quiet, able to give no PEEP (2-3cm are mandatory on bellows-type), more precise delivery of TV (due to compliance and leak compensation ,fresh gas decoupling, and the rigid piston design), eliminates the need of a bulky and costly sensor close to the patient’s airway (to measure compliance and leaks), and uses electricity as the driving force of the piston.

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69
Q

Disadvantages of the piston vents

A

Unable to use bellows to visualize pt breathing patterns, quiet (not as easy to hear the cycling of breaths), can entrain air - resulting in delivering tidal volumes with less oxygen than intended

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70
Q

Inspiratory pause increases the inspiratory time by ___%

A

25%

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71
Q

Normal flow rate for ventilators

A

4-6 x minute ventilation

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72
Q

The respirometer is made of what two parts?

A

The transducer cartridge and tidal volume sensor clip

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73
Q

NIOSH recommendations for maximum room concentrations of anesthetic gases

A

Volatile agent alone- 2ppm
Nitrous alone - 25ppm
Volatile agent with nitrous - .5ppm

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74
Q

How often is the air in the OR turned over?

A

20 times per hour
OR
Once every three minutes

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75
Q

Gases to go to scavenge come from what two sources?

A

The APL valve and ventilator relief valve.

May also come from capnogram (if gases are taken for sampling) and driving gas.

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76
Q

Characteristics of transfer means tubing

A

Short and wide (30mm or 19mm) to decrease resistance. Kink resistant. Female fitting. Looks different than the other tubing (yellow and stiff).

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77
Q

The scavenging interface limits pressures downstream from the gas collecting assembly between _______cmH2O

A

-.5 to +5 cmH2O

In this way, pressures in the scavenging system are prevented from being transferred to the breathing system

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78
Q

In a closed scavenging interface, gases are released into the OR atmosphere if pressure within the system reaches ____cmH2O

A

+5cm H2O

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79
Q

In the closed interface, room air is entrained into the system if the system pressure reaches ____cmH2O. A backup valve exists in case this primary release valve fails, and it opens at ______cmH2O

A

-.5 cmH2O and -1.8 cmH2O

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80
Q

Most hospital vacuums can receive gases at a rate of ______L/min

A

75 L/min

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81
Q

Is a passive or active scavenging more common in hospitals?

A

Active

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82
Q

2 components necessary to receive an EtCO2 reading

A

Ventilation AND perfusion

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83
Q

Gold standard for proper ETT placement

A

EtCO2

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84
Q

What are the contraindications to capnography?

A

PSYCH! There are none.

85
Q

During general anesthesia, how much higher is PaCO2 than the EtCO2 reading?

A

2-5mmHg

86
Q

CO2 gradient can be used to evaluate the amount of _____

A

Dead space

87
Q

How is CO2 measured with calorimetrics?

A

Uses metacresol purple impregnated paper, which changes color in the presence of carbonic acid

88
Q

Can CO2 be measured transcutaneously?

A

Yes, but we didn’t really learn about it.

89
Q

What is the most common method of measuring EtCO2 and how is it done?

A

Infrared absorption spectrophotometry. A sample of the gas is subjected to IR radiation at different wavelengths. The amount of CO2 is determined by detecting the absorbance at specific wavelengths and filtering absorbance related to other gases.

90
Q

Disadvantages of mainstream capnography are related to

A

The heat created by the sensor and the weight of the sensor

91
Q

Which is more common, sidestream or mainstream capnography?

A

Sidestream. The sensor should be placed as close to the patient as possible, or else the sample will be diluted with other gases.

92
Q

How much air does a sidestream capnograph aspirate per minute?

A

Usually 50cc/min, but may be as high as 500

93
Q

Problem with sidestream capno in prediatrics

A

They have lower TV, which may dilute the sample

94
Q

Normal EtCO2 reading

A

30-40mmHg

95
Q

Does proper EtCO2 indicated that the ETT is placed properly?

A

No.

96
Q

In severe hypotension, would you expect EtCO2 to increase or decrease?

A

Increase

97
Q

Describe the Capno waveform for obstructive lung diseases (COPD, asthma, bronchoconstriction, acute obstruction)

A

Takes longer to expire, so there will be a slow rise in Phase II and a very short or absent Phase III

98
Q

Phase I on Capno may be higher than 0 if

A

CO2 absorber is exhausted, equipment deadspace, inadequate FGF

99
Q

The little blip in the EtCO2 tracing when a patient is showing a return of spontaneous ventilation is called

A

a “curare cleft”

100
Q

Cardiac oscillations in capno are caused by

A

reflections of cardiac impulses through the airways

101
Q

Causes of rising CO2 when ventilation has been unchanged

A

Exhaustion of CO2 absorber, release of tourniquate, release of a major vessel clamp, insufflation of CO2 into peritoneal cavity, IV bicarb administration, equipment defects, and MALIGNANT HYPERTHERMIA.

102
Q

Basic end-products of CO2 absorption

A

Water, a carbonate, and heat

103
Q

Two common CO2 absorbents

A

Soda lime and Amsorb Plus (Calcium hydroxide lime)

104
Q

Components of Soda Lime

A 
4% NaOH
1% KOH
15% H2O
.2% silica
80% CA(OH)2
105
Q

The average person expels ______L per hour of CO2

A

12-17L

106
Q

What will happen to the color indicator with rest?

A

Color reverts back with rest, but will change color to what it should be as soon as it is exposed to CO2.

107
Q

What is the most common color indicator?

A

Ethyl violet. The absorber is white when new and purple when exhausted.

108
Q

Sie of CO2 absorber granules

A

4-8 mesh

109
Q

Hardness number for granules should be at least

A

75

110
Q

What can happen with excessive granule powder?

A

Channeling resistance and caking

111
Q

What can cause granules to dry out?

A

High flows

112
Q

Desiccated soda lime can degrade sevoflurane, isoflurane, and enflurane into _______

A

Carbon monoxide

113
Q

Desiccate soda lime can degrade sevoflurane and halothane into ______

A

Compound A, which is a nephrotoxic compound.

114
Q

Is it ok to change just one of two absorbant canisters?

A

No. Both must be changed at the same time. They are best friends and don’t like to be separated.

115
Q

Who specifies and enforces the purity of medical gases?

A

US Pharmacopoeia specifies and the FDA enforces it

116
Q

This organization is responsible for manufacturing, filling, qualification, transportation, storage, handling, maintenance, re-qualification, and disposition of medical gas cylinders and containers

A

the Department of Transportation (DOT)

117
Q

What does the “service pressure” refer to on a gas cylinder

A

The pressure that should not be exceeded inside the container

118
Q

An engraved star on the cylinder neck means

A

The cylinder may be retested every 10 years instead of every 5

119
Q

An engraved + sign on the cylinder means

A

The cylinder can be charged up to 10% in excess of its service pressure

120
Q

Pin sizes in the PISS system

A

The pins are 4mm wide and 6mm long, except pin 7, which is slightly thicker

121
Q

The cylinder color can always be used to identify its contents

A

No. You should always read the label.

122
Q

Vapor pressure of enflurance

A

172mmHg

123
Q

Vapor pressure of isoflurance

A

240mmHg

124
Q

Vapor pressure of halothane

A

244mmHg

125
Q

Vapor pressure of sevoflurane

A

160mmHg

126
Q

Vapor pressure of desflurance

A

669mmHg

127
Q

Solubility of O2 in blood

A

.003mL / 100mL blood / mmHg partial pressure

128
Q

Solubility of CO2 in blood

A

067mL / 100mL blood / mmHg partial pressure

129
Q

What is the critical temperature of O2?

A

-119 C. Above this temperature, the gas will not liquify no matter how much pressure is applied. If we want liquid oxygen, we have to cool it to at LEAST -119 C.

130
Q

Critical temp for N2O

A

39.5 C. Room temp is 20 C. Therefore, we can liquify N2O at room temp with enough pressure (745psi to be exact)

131
Q

What is adiabatic cooling?

A

A temperature change that occurs without gain or loss of heat. This occurs when matter changes phase, ex- when N2O tank is opened fully, frost can form on the outlet due to cooling

132
Q

Joule-Thompson Effect

A

Expansion of a gas causes cooling. Ex- as gas leaves the cylinder, it feels cool, and condensation may accumulate on the cylinder

133
Q

This determines flow when flow is laminar

A

Viscosity. Flow is laminar at low flow rates. At low flow rates, viscosity determines rate of flow.

134
Q

This determines flow when flow is turbulent

A

Density. Flow is turbulent at high flow rates. At high flow rates, density determines rate of flow. Ex- using heliox will improve flow at high flow rates because it is less dense.

135
Q

How can you minimize turbulence and decrease WOB?

A

Decrease the flow rate

136
Q

Factors that switch laminar to turbulent flow

A

Increased velocity, irregularities in the tube, and bends more than 20 degrees

137
Q

The Venturi tube works using what theorem?

A

Bernoulli’s Theorem

138
Q

Clinical application of Beer’s Law

A

Pulse-oximeter

139
Q

Oxyhemoglobin absorbs this wavelength

A

940nm

140
Q

Deoxyhemoglobin absorbs this wavelength

A

660nm

141
Q

Will carboxyhemoglobin give you a false high or false low pulse ox reading?

A

False high. Carboxy is not picked up by the pulse oximeter

142
Q

How do HgbF and HgbS effect pulse-ox?

A

PSYCH AGAIN! They don’t!

143
Q

Effect of methylene blue and isosulfan blue on pulse ox reaing

A

FALSE LOW

144
Q

Effect of indocyanine green and indigo carmine on pulse ox

A

Slight decrease

145
Q

Effect of blue nail polish on pulse-ox

A

False low

146
Q

Micro-shock

A

Current applied in or near the heart. Due to pacing wires or faulty equipment during cardiac cath. Micro-shock requires direct connection to the heart muscle.

Usually 50-100 microamps

147
Q

Macro-shock

A 
Current is distributed though the body. Usually due to faulty wiring or improper grounding.
Btw 1-6000 milliamps 
1mA - skin tingling/perception
5mA - maximal "harmless" current
10-20mA - let go of source
50mA - pain, LOC, mechanical injury
100-300mA - V-fib, resp intact
6000mA - complete physiologic damage
148
Q

What does 2% lidocaine mean?

A

There are 2g of lidocaine in 100cc.

Alternatively, there are 20mg per mL

149
Q

What does 1:100,000 epi mean?

A

1g per 100,000mL

Alternatively, there are 10mcg per mL

150
Q

How many mcg/mL are in a 1:200,000 concentration?

A

5mcg/mL

151
Q

In the Tec-6 Vaporizer, the desflurane is heated to ____C to provide a vapor pressure of _____mmHg

A

39C and 1500mmHg (2atm)

152
Q

Essential requirements of the breathing system

A

CO2 removal
Minimal Deadspace
Low resistance

153
Q

Desirable breathing system characteristics

A

Economy of fresh gas, conservation of heat and humidity, light weight, portable, adaptability (for children, adults, spont/controlled ventilation), environmental pollution reduction

154
Q

T/F: Higher FGF is associated with less CO2 rebreathing in any circuit

A

True

155
Q

When does the concentration inspired most closely resemble that delivered from the common gas outlet?

A

When REbreathing is minimal or absent. Otherwise, you don’t know exactly how much is circling back to be mixed with the FGF. Less mixing means more delivery of what is coming out of the common gas outlet.

156
Q

Why is acidosis bad?

A

Will cause increased HR, arrhythmias, and decreased contractility

157
Q

Two types of open systems

A

Insufflation/Blow-By and open drop

158
Q

A nasal cannula is an example of what type of system?

A

Open system

159
Q

Characteristics of open systems

A

No rebreathing
No valves
No reservoir bag

160
Q

Examples of insufflation

A

Blow-by, tent, bronchoscopy port, nasal cannula, steal induction

161
Q

Disadvanages of open systems

A

Can’t assist ventilation, poor control of anesthetic depth, lots of environmental pollution, may have CO2 accumulation depending on method

162
Q

Schimmelbusch Mask uses what anesthetic agents?

A

ECH:
Ether
Chloroform
Halothane

163
Q

The Mapleson system without corrugated tubing

A

C (very short system)

164
Q

Difference between Mapleson A and B&C

A

A has FGF from the end with the APL valve closest to patient. B&C also have APL valve closest to the patient, but the FGF is much closer.

165
Q

Thing to remember with controlled ventilation with Mapleson regarding APL

A

If giving manual breaths, you will have to close the APL valve in order to do so. This will result in less CO2 being removed from the system

166
Q

What should you do if your EtCO2 is increasing on a mapleson system?

A

Increase flows

167
Q

Normal minute ventilation

A

We learned that about 7L/min is normal for minute ventilation.

168
Q

Is the Bain circuit really used anymore?

A

Not really, but they ask about it on boards

169
Q

How does the ambu bag prevent CO2 rebreathing?

A

It has non-reabreathing valves and you use a high FGF rate

170
Q

Can you give inhalational gases with Mapleson systems?

A

Yes. Just need to use various adapters.

171
Q

Components of the circle system

A 
FGF source
Insp and exp limbs
Insp and exp unidirectional valves
Y-piece connector
APL valve
Reservoir bag
CO2 absorber
172
Q

Available lengths of the circle system tubing

A

40, 60, or 72 inches

173
Q

All breathing tubes will be this diameter, while facemasks and ETTs have a standard opening of this size

A

Breathing tubes are 22mm

Adapter will be available because the openings for facemask and ETT are 15mm

174
Q

Single-Limb Universal F Circuit. What da fuck is it?

A

It is for a circle system, but the exp and insp limbs are contained inside a single tube that has a bifurcation down the middle

175
Q

The circle system can be used in what three ways?

A

Semi-open, semi-closed, and closed. Depends on adjustment of APL valve. FGF will have to vary for what system is being used.

176
Q

Size of the neck of the reservoir bag

A

22mm

177
Q

Reservoir bag is made of _____

A

neoprene or rubber

178
Q

Reservoir bag can hold this much gas and can extend to this pressure before the pressure is delivered to the patient

A

3L and 60cmH2O

179
Q

During mechanical ventilation, does the APL valve come into play at all?

A

No.

180
Q

Semi-Open circle system

A

APL valve is open all the way, no rebreathing of gases (everything escapes via the APL valve because the scrubber has more resistance), because no rebreathing you need high FGF (10-15L/min), no conservation of gases, heat or humidity

181
Q

Most common type of circle system in the US?

A

Semi-closed. Uses lower flows (1-3L/min), APL valve is partially closed, CO2 absorber comes into play, we rebreathe other gases, and heat and humidity are retained.

182
Q

Closed circle system

A

APL is closed all the way, so we have to use VERY low flows. Provide JUST enough oxygen to meet O2 consumption. This conserves gas as much as possible. Used in third world countries.

183
Q

Typical flow with a closed system

A

200mL/min

184
Q

O2 Consumption formula (for an average healthy patient)

A

10 x kg^3/4

185
Q

A third of malpractice suits result from

A

Disconnects and misconnects of the circle system circuit. The system has at least 10 points of connection. Higher probability of error.

186
Q

Circle System Leak Test

A

Set all gas flows to zero, close the APL valve, and occlude the Y piece. Pressurize the system to 30cmH2O using the O2 flush valve. Make sure that the system sustains the pressure for at least 10seconds and that the sustained pressure alarm goes off. Then depressurize the system by opening the APL valve to ensure that is working properly. This does NOT assess the integrity of unidirectional valves

187
Q

What is contained in the intermediate pressure system?

A 
THE PNEUMATIC PART OF THE MASTER SWITCH
Pipeline sources
Pressure regulators
O2 Flush Valve
O2 Pressure Failure Device
O2 supply failure alarm
Flow meter control valves/knobs
188
Q

What is the name of the chain linked mechanism between nitrous and O2?

A

Hypoxia prevention safety device

189
Q

What is the pressure threshold for the O2 pressure sensor shut-off valve?

A

20psi. This will shut off nitrous and air

190
Q

What is the OFPD?

A

Oxygen failure pressure device. Proportioning type system for the pressure sensory shut-off

191
Q

Are second stage regulators present in all machines?

A

No

192
Q

Most important monitor on the machine?

A

Oxygen analyzer

193
Q

What is the only monitor that detects problems downstream from the flow control valves?

A

The oxygen analyzer

194
Q

1993 Negative-Pressure Leak Test

A

Turn off the machine master switch, all flows and vaporizers. Attach the suction bulb to the CGO. Bulb should remain collapsed for at least 10 seconds.

195
Q

Two checks of the circle system

A

Leak Test (occluding the Y piece and stuff)

Flow test (checking the unidirectional valves)

196
Q

An open scavenging interface requires a

A

vacuum

197
Q

Scavenging System Check

A

Ensure all connections are correct
Fully open APL valve.
With low flows, ensure that the bag collapses and that the pressure gauge reads 0.
Press the O2 flush valve to fully inflate the reservoir bag and ensure that the pressure does not exceed 10cmH20.

198
Q

EtCO2 is a reflection of what?

A

PACO2 AND PaCO2

199
Q

When would you see a decrease in EtCO2?

A

PE (causes a V/Q mismatch and you would see an elevated A-a CO2 gradient), cardiac arrest, disconnection, hyperventilation, sampling error (high sampling rate with elevated FGF)

200
Q

At what point do you change the absorber?

A

With 50-70% color change

201
Q

Air space occupies what percent of the volume of the canister?

A

48-55%

202
Q

Which anesthetics can degrade to carbon monoxide if exposed to a desiccated absorber?

A 
DIES
Desflurane
Isoflurane
Enflurane
Sevoflurane
203
Q

These anesthetics degrade into Compound A if exposed to desiccated absorber?

A

Sevoflurane

Halothane

204
Q

Latent heat of vaporization

A

Number of calories required to change 1g of liquid in vapor without a temperature change

205
Q

Can you do a case without an oxygen analyzer?

A

Absolutely not.

206
Q

The bimetallic strip is called the

A

Temperature compensating valve

207
Q

What is the critical temp of O2?

A

-119C

208
Q

What is the critical temp of N2O?

A

39.5C

209
Q

Effect of Methgb on pulse ox

A

SaO2 > 85 = FALSE LOW

SaO2 < 85 = FALSE HIGH

Anesthesia (1 decks)

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