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Anesthesia 101 > Physics and Monitoring > Flashcards

Physics and Monitoring Flashcards

1
Q

3 ways to minimize oxygen when using anesthesia machine as an ICU ventilator

A
  1. Use electrically powered ventilator
  2. Converting ventilator drive gas to air instead of oxygen for pneumatically driven bellows ventilators
  3. Using low fresh gas flows
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2
Q

Pneumatically-driven bellows ventilators generate (inspiratory/expiratory) effort. Volume of ventilator drive gas that is roughly equivalent to ______ is injected into the bellows chamber.

A

inspiratory

the pt’s tidal volume

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3
Q

In most pneumatically-driven bellows ventilators, the ventilator drive gas is _________. But it can be converted to use ____ instead to conserve it.

A

oxygen

air

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4
Q

The auxiliary oxygen tank will begin to deliver oxygen to an anesthesia machine if the pipeline pressure drops below __ PSI

A

45

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5
Q

Ultrasound is a high frequency sound with vibrations above _____ cycles per second

A

20,000

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6
Q

A full E-cylinder contains ___ L of oxygen at ____ PSIG

A

660L

2000 PSIG

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7
Q

How to calculate time remaining before a tank is depleted

A

Liters remaining / (current flow rate in Liters/min)

or

take current pressure (PSIG) divided by 3, then dividing by flow rate

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8
Q

When a vaporizer is designed for a volatile anesthetic with a lower saturated vapor pressure (SVP)is misfilled with a volatile anesthetic with a higher SVP, the output volume percentage will be (higher/lower) than the [ ] set with the dial

A

higher
- the higher the SVP, the higher the partial pressure of anesthetic, and therefore the higher percentage of total gas leaving the chamber

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9
Q

the adjustable pressure limiting (APL) valve, aka the _______ valve, cannot be positioned between the ____ and the _____ to prevent rebreathing of CO2 in a traditional circle system

A

pop off valve

patient and inspiratory

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10
Q

_______ is the most common breathing system in the US

A

The circle system

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11
Q

A unidirectional valve must be positioned between the ______ and _____ in order to prevent rebreathing of CO2 in a traditional circle system

A

patient

both the inspiratory and expiratory limbs

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12
Q

Fresh gas flow cannot come into the circle system between the ____ and the ____ in order to prevent rebreathing of CO2 in a traditional circle system

A

patient and expiratory valve

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13
Q

The circle system can be used in 3 different ways depending on the fresh gas flow

A
  1. semi-open system
  2. semi-closed system
  3. Closed system
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14
Q

Semi-open system

A

high fresh gas flows with no rebreathing

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15
Q

Semi-closed system

A

lower fresh gas flows with some rebreathing

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16
Q

Closed system

A

fresh gas flow matches pt consumption with complete rebreathing

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17
Q

_______ protect persons from electrocution by turning a normal “grounded system” (that exists outside the OR) which only needs a single fault to cause electrocution into a “protected” system in which two faults are needed to deliver a shock

A

Line isolation systems

- Isolation transformer + line isolation monitor

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18
Q

Lasers in the OR is assoc with (4)

A
  1. gas embolism
  2. retinal injury
  3. OR fires
  4. laser plume creation

*NOT shown to cause defibrillator discharge

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19
Q

Wandering baseline ECG tracing, especially in leads III and aVR, is commonly caused by _____

A

loose ECG electrode
Poor skin contact
moving pt (respirations)

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20
Q

Lead II measures the voltage between the ___ and ___ electrodes

A

Red (left leg)

white (right arm)

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21
Q

Lead III measures the voltage between the ___ and ___ electrodes

A

red (left leg)

black (left arm)

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22
Q

Lead aVR (augmented vector right) measures the voltage between the ___ and ___ electrodes

A

white (right arm)

combination of black (left arm) and red (left leg)

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23
Q 
Color code these gas types:
Carbon dioxide - 
Nitrous oxide - 
Nitrogen - 
Helium -
Oxygen -
Air -
A

Carbon dioxide - gray
Nitrous oxide - blue
Nitrogen - black
Helium - brown

Oxygen - green
Air - yellow

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24
Q

The doppler effect can be used in ECHO to determine both the ____ and ____

A

direction

speed of flow

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25
Q

_____ technique is the most commonly utilized invasive method for assessing cardiac output

A

Thermodilution cardiac output

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26
Q

Induction agent that most enhances motor evoked potential amplitudes

A

Ketamine

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27
Q

Somatosensory evoked potentials (SSEP) provides information regarding the integrity of the _____ and are measured by stimulating the peripheral or cranial nerve and measuring the resultant EEG

A

ascending neurons

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28
Q

Motor evoked potentials (MEP) are used to evaluate the integrity of the ______.

A

descending motor neuronal pathways

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29
Q

Etomidate may enhance ____ evoked potentials but does not increase ____ evoked potentials

A

somatosensory evoked potential

motor evoked potential

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30
Q

a 5 MHz probe will provide (better/worse) tissue penetration than a 7.5 MHz probe

A

better

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31
Q

Higher frequency (lower wavelength) means better ______ but worse _____

A

resolution

penetration (depth)

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32
Q

Lower frequency (increased wavelength) gives better _____ but sacrifices _____

A

penetration (depth)

resolution

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33
Q

Velocity =

A

frequency * wavelength

VWF

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34
Q

In a pt with Fontan circulation, ______ circulation bypasses the heart to reach the lungs. Used for pts with ______ cardiac system.

A 
venous
univentricular
- tricuspid atresia
- hypoplastic L or R heart
- double inlet L ventricle
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35
Q

In Fontan circulation, ______ pacing leads may be placed for permanent pacing rather than _____ pacing, d/t access.

A

Epicardial

Transvenous

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36
Q

A curved array US probe maximizes _____, and is better at _____.

A

returning US waves

deeper structures

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37
Q

A Linear array US probe maximizes _____, at the expense of _____

A

resolution

less penetration

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38
Q

Cerebral perfusion pressure =

Spinal cord perfusion pressure =

A

MAP - ICP

MAP - CSF pressure

*Two most common way to improve SCPP during aortic surgery is either increase MAP or decrease CSF pressure using lumbar CSF drain

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39
Q

SVR = ?

A

80 * (MAP - RAP) / CO

R atrial pressure = CVP

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40
Q

Half tank of N2O would read a pressure of ___

A

745 psig
- regardless of the volume of N2O in the tank, the pressure will read 745 psig until ALL liquified gas is used up (~250 L or 16%)

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41
Q

A full tank of N2O contains ____ at a pressure of 745 psig

A

1590L

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42
Q

atmospheric pressure at sea level is ____

A

14.7 psig

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43
Q

A full and Half tank of O2 would read a pressure of ___

A

Full: 2200 psig

Half: 1100 psig

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44
Q

A full tank of O2 contains ____ at a pressure of 2200 psig

A

660L

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45
Q

Raising or lowering a pressure transducer (ie. art line, pulm a. cath, intracranial pressure) relative to the pt will alter the pressure reading.
a 10 cm change in height will alter pressure reading by _____ mmHg

A
  1. 5mmHg
    - Raising transducer (lowering pt): lowers the pressure reading
    - Lowering transducer (raising pt): increases the pressure
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46
Q

What happens to the pressure reading if you:

  • Raising transducer (lowering pt):
  • Lowering transducer (raising pt):
A
  • Raising transducer (lowering pt): lowers the pressure reading
  • Lowering transducer (raising pt): increases the pressure
  • 10 cm change in height will alter pressure reading by 7.5mmHg
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47
Q

The bellows within the circle system is in a (high/low) pressure system, and will STILL function in the presence of leaks in the low pressure system

A

High

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48
Q

The flowmeters and vaporizers within the circle system is in a (high/low) pressure system, and will NOT still function in the presence of leaks in the low pressure system.

A

low

- could lead to administration of hypoxic gas mixtures or insufficient amts of anesthetics

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49
Q

The adjustable pressure limiting (APL) valve is typically taken out of the circuit when the ventilator is switched to mechanical ventilation mode. What does this mean?

A

The system will function the same regardless of whether the APL valve is open or closed

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50
Q

Which one consumes more gas, using gas from the pipeline supply or E-cylinders?

A

E-cylinders

- so you should hand ventilate if there is a failure with the pipeline supply

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51
Q

The a typical ascending (standing) bellows ventilator, the bellows (rise/fall) during pt exhalation

A

rise

*the bellows can act as an indicator of a leak or disconnected circuit

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52
Q

The a typical ascending (standing) bellows ventilator, the bellows (rise/fall) during pt inhalation

A

fall

*the bellows can act as an indicator of a leak or disconnected circuit

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53
Q

3 most important preop anesthesia machine checks

A
  1. Oxygen analyzer calibration
  2. low pressure circuit leak
  3. circle system test
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54
Q

A suction bulb is attached to the _____ and must remain collapsed for at least _____ seconds to pass a negative pressure leak test. If this is successful, the flowmeter or vaporizer is considered safe.

A

Common gas outlet

10 s

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55
Q

Fresh gas flow must be greater than or equal to ___ times minute ventilation in Mapelson ____ circuits.

A

1-2x

D, E, F

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56
Q

Mapelson D, E and F are ____ circuits that are not very efficient for spontaneous ventilation, but is most efficient for ______.

A

Semi-open circuits

Controlled ventilation

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57
Q

Advantages of a Bain circuit (Mapelson D) (4)

A
  1. conservation of moisture d/t partial rebreathing
  2. warming of fresh gas inflow
  3. scavenging waste is easier from APL valve
  4. advantageous when access to the pt is limited
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58
Q

Which mapelson circuit requires higher fresh gas flows (2.5x minute ventilation)?

A

D (bain)

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59
Q

Mapleson __ is better for spontaneous respirations, and ___ is better for controlled ventilation

A

A - spontAneous

D - controlleD

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60
Q

If a pt is able to do a head lift, or hand grip, or effective cough, the TOF ratio is ____

A

0.7 < TOF Ratio < 0.9

T4:T1 height ratio

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61
Q 
How much receptor is suppressed?
1 Twitch
2 Twitch
3 Twitch
4 Twitch
A

1 Twitch: > 90%
2 Twitch: 80-90
3 Twitch: 70-80%
4 Twitch: 65-75%

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62
Q

Limitations to:

MAP = 2/3 diastolic BP + 1/3 Systolic BP

A

Can only calc if systolic and diastolic P are known (ie: auscultation)

Heart rate dependent (only good if HR are normal, not fast)

63
Q

During oscillometric non-invasive BP measurement, how is MAP determined?

A

Point of maximal amplitude of oscillations

  • point when inflated cuff is completely compressing artery
  • point when deflated cuff is not able to sense oscillations
64
Q

The ______ leak test may check for leaks in the low-pressure system of the anesthesia machine.
- ie: suction bulb compression

A

negative pressure leak test

65
Q

ECG “wandering baseline” usually happens in leads ____, which is commonly caused by _____

A

Leads III and aVR

Loose ECG electrodes

66
Q

What does interference from an alternating current (AC) on ECG look like?

A

Thick ECG tracing that alternates up and down 60 times/second (60 hertz)

67
Q

What is the first sign that a hypoxic mixture is being delivered (ie. pipeline crossover or mix-up where O2 switched with another gas)?
What should you do?

A

alarming of oxygen analyzer

- at this point, disconnect the pipeline supply gases

68
Q

The oxygen supply alarm goes off, the oxygen analyzer detects _______, you should now disconnect the machine from the hospital’s oxygen supply (pipeline supply gases)

A

decreasing FiO2 delivery

- hypoxic mixture is being delivered (ie. pipeline crossover or mix-up where O2 switched with another gas)?

69
Q

Which lead is most sensitive for monitoring atrial electrical activity on ECG? Second most?

A

Lead II

  • parallel to normal axis of atrial depolarization
  • p waves are most prominent

*lead V1 is second most sensitive

70
Q

Which lead is most sensitive for monitoring arrhythmias on ECG?

A

Lead II

71
Q

Three lead (RA, LA, and LL) ECG monitoring allows for uninterrupted monitoring of Lead I, II, or III, which is good for monitoring for ______, but poorly sensitive for ______.

A

Good

  • atrial arrhythmias
  • R wave changes

Bad

  • ST segment changes
  • Complex ventricular arrythmias
72
Q

What do these leads contribute to sensing on ECG?

  • V1
  • V4
  • V5
A
  • V1: arrhythmia detection

- V4 or V5: ischemia detection

73
Q

WHat happens to BP cuff reading if the point of measurement is elevated above the heart?

A

Decrease

  • inversely proportional to height of the heart
  • 0.75 mmHg per cm
74
Q

Sites correlating with core temperature

A
  1. Esophageal
  2. Tympanic
  3. Pulmonary artery
  4. Nasopharyngeal
75
Q

How does a microshock occur?

How to prevent it?

A

Result of a new grounded current that can result in electric shock with small current values

Prevention:

  • Equipment ground wire
  • prevent grounding of anesthesiologist and pt
76
Q

What device is placed to monitor current imbalance in grounded circuits?

  • Breaks the current flow if there is an imbalance of current flow btwn “hot” and “neutral” wires
  • Threshold is 5 mAmps (prevents macroshocks)
A

ground fault circuit interrupter (GFCI)

77
Q

What device is used to measure the total leakage current of the non-grounded isolated power circuit in the OR?

A

Line isolation monitor

78
Q

What device is a very low impedance wire that is used to allow leakage current to pass through to prevent build up of leakage current? It also prevents electric shock with pt grounding (electricity follows path of least resistance - wire instead of pt)

A

Equipment ground wire

79
Q

What device prevents macroshock?

microshock?

A

macroshock

  • ground fault circuit interrupter
  • line isolation monitor

microshock
- Equipment ground wire

80
Q

The radius of a vessel is directly proportional to ____ and inversely proportional to ____

A

flow

resistance

81
Q

How do these changes affect blood flow:

  • Double blood viscosity
  • Half the blood viscosity
  • Double radius of artery
  • Half the radius of artery
A

Double blood viscosity
- half the flow

Half the blood viscosity
- double the flow

Double radius of artery
- exponentially increase blood flow (Q ~ r^4)

Half the radius of artery
- exponentially reduce blood flow

82
Q

Which Law dictates flow in relation to radius, viscosity, and length?

A

Poiseuille Law

83
Q

Rebreathing of exhaled gases will occur if _____ exceeds fresh gas flow, which causes lower FiO2

A

minute ventilation
- average ~ 5L/min

*need to keep FGF at least equal to MV to prevent rebreathing

84
Q

What is the vital capacity of an average 70kg pt with nl PFT?
How much would their minute ventilation be if they took 2 vital capacity breaths in 1 minute?

A

5 L

5 L * 2 = 10L/min

85
Q

What is SUPERIOR when it comes to preoxygenating pts, 4 deep breaths (vital capacity) over 30 seconds, or 3 min of tidal volume breathing?

A

3 min of TV

86
Q

How is pressure of inspired oxygen (PiO2) correlated to fraction of inspired oxygen (FiO2)?

A

Directly proportional

- doubling PiO2 -> doubling FiO2

87
Q

At sea level with room air, FiO2 =

A

21%

88
Q

When is the sub-ambient pressure alarm on the ventilator triggered?

*This is different from high or low pressure alarm

A

Pressure in the breathing circuit falls below atm pressure (typically -10cm H2O)

  • NG tube placed in trachea
  • Pt inhaling against collapsed reservoir bag
89
Q

The ____ electrode is used to measure partial pressure of oxygen and required a voltage/ power source (ie. battery) to maintain linearity btwn measurements

A

Clark

- ie: ABG or anesthesia machines

90
Q

A _____ electrode is used to measure oxygen content, through electrons and their relation to electrolyte fluid. A batter is not needed.

A

Galvanic

- ie: scuba equipment

91
Q

A _____ electrode is used to measure pCO2, based on the principle that pH and pCO2 change in a linear fashion with temp.

A

Severinghaus

92
Q

Infrared (IR) absorption spectrophotometry is used to detect _____, bc each gas absorbs a different wavelength of infrared light.

It is the most commonly used method for gas analysis with anesthesia machines.

A

Volatile anesthetics
CO2
N2O

93
Q

Clark, galvanic, and paramagnetic electrodes measure _____.

Severinghaus electrode measures _____.

Sanz electrode measures ____.

A

Oxygen

CO2

pH

94
Q

How do different elevations affect the MAC of anesthetic gases delivered through a variable bypass vaporizer (sevo, iso, enflurane)?

A

Minimal effect on MAC at higher / lower elevations

95
Q

How do different elevations affect the MAC of anesthetic gases delivered through a dual-gas blender (desflurane)?

A

Anesthetic gas will be directly proportional to atmospheric pressure change
- aka gas delivered will be inversely proportional to altitude
- ie: normal atm = 760 mmHg
if pt was at sea level and atm = 380 mmHg, MAC of desflurane is 0.5.

96
Q

6% desflurane at 0.5 atm = to __% desflurane at 1 atm, or about ___ MAC

A

3% desflurane

0.5 MAC

97
Q

Desflurane
6% Des is 1 MAC at 1 atm (760 mmHg)
- To achieve 0.25 MAC, barometric pressure needs to be ___
- To achieve 1 MAC at 0.5 atm, des dial needs to be ___

A

190 mmHg
- Anesthetic gas will be directly proportional to atmospheric pressure change

12%
- gas delivered will be inversely proportional to altitude

98
Q

In the absence of electricity, what can you still provide under GA?

A
  1. Manual positive pressure ventilation
    - breathing bag w/ APL valve
  2. Air and N2O
  3. Oxygen delivery
  4. Anesthetic gases if Vaporizer is mechanical (variable bypass)
99
Q

In the absence of electricity, what CAN’T you provide/monitor under GA?

A
  1. Capnography
    - mass spectrometer and IR analyzer both use electricity
  2. Monitoring capabilities
  3. Desflurane
    - requires proper heating
  4. Cassette-type vaporizers
100
Q

_____ law indicates that at a constant temp, the [ ] of a dissolved gas in solution is DIRECTLY proportional to partial pressure of that gas

A

Henry’s law
C = kP

K = solubility constant

*increasing volume % of anesthetic gas -> increases alveolar partial pressure -> increases speed of induction

101
Q

_____ law indicates that a fixed mass of gas at a constant temp will have a constant pressure-volume

A

Boyle’s law
P1V1 = P2V2

  • If gas is pressurized, it takes up a smaller volume
  • Water boyles at a constant temperature
102
Q

_____ law states that the pressure of a given mass of gas is DIRECTLY proportional to its temperature when at a constant volume

A

Guy-Lussac’s law
P1/T1 = P2/T2

*Air in ETT cuff at room temp, gradually warms to body temp, and pressure in cuff increases as well

103
Q

_____ law states that the volume of a given mass of gas is directly proportional to its temperature when at a constant pressure

A

Charles law
V1/T1 = V2/T2

*prince Charles is under constant pressure to be king

104
Q

_____ law indicates that the total pressure exerted by a mixture of gases is the sum of the individual gases’ partial pressures.

A

Dalton’s law
- Pt = P1 + P2 + P3 ect

  • explains why pts with elevated PaCO2 will have a reciprocal decrease PaO2
  • explains why E-cylinders containing a mixture of different gases, will have the partial pressures equal the total gas pressure
105
Q

(True/False) A noncompensating pneumatic bellows ventilator system takes into account the added volume of fresh gas flow during inspiration when delivering a set tidal volume

A

False

  • You need to also factor in fresh gas flows on top of the set delivered tidal volume
  • ie: if you set 800mL, but pt is also getting O2 and Air fresh gas flow, you need to know that the pt is getting actually more than 800 mL per breath
106
Q

Minute ventilation is ____

A

TV * RR

amt of air person breaths / min

107
Q

What types of carbon dioxide absorbents are more likely to cause formation of carbon monoxide?

A

Absorbents with Strong bases (KOH or NaOH)

  • Baralyme (4.6% KOH)
  • Sodalime (2.5% KOH)
108
Q

Which new absorbents contain mostly Ca(OH)2 and almost no strong bases (KOH and NaOH), making them at little risk of Carbon monoxide formation?

A 
Sodasorb
Sodalime II
Spherasorb
Lithium hydroxide
Amsorb
109
Q

Carbon dioxide absorbents are used in modern anesthetic practice in ____ and _____ systems

A

semi-closed

closed

110
Q

All volatile anesthetics undergo degradation by absorbents that contain sodium and/or potassium hydroxides.
Sevoflurane, desflurane, enflurane, and isoflurane degrade into ____

A

Sevo: compound A

Desflurane, enflurane and Isoflurane: Carbon monoxide

111
Q

______ allows preferential use of the pipeline oxygen when the higher pressure in this system is sensed, sparing the lower pressure, back up oxygen tank for emergencies.

A

First stage oxygen regulator

112
Q

What nail polish color is LEAST likely to interfere with pulse oximeters (which analyzes two wave light: red 660 and infrared 940 nm light)?

A

Red

- absorbs little light at 660 and 940, so causes minimal interference

113
Q

The potency of volatile anesthetics is a function of ______ (NOT inspired percent concentration).

A

Partial pressure

- changes with altitude

114
Q

The international color code of oxygen containers

A

White

*in the US its green

115
Q

Quick way to calculate volume remaining in oxygen tank

A

Pressure (PSIG) / 3

Then divide that by flow (L/min), and you should get time remaining

116
Q

A _____ circuit system is a low flow technique using a circle system in which total fresh gas flow (oxygen and inhalational anesthetic) is equal to oxygen consumption and inhalational anesthetic metabolism

A

Closed circuit

117
Q

In a ______ circuit system, the majority of the gas inhaled with each breath is that which was exhaled in the previous breath (nitrogen, water, unmetabolized volatile anesthetic)

A

Closed circuit

118
Q

Advantages of closed circuit or low flow circuit (5)

A
  1. decrease use of fresh gas
  2. decrease volatile anesthetic use
  3. conservation of heat and humidity
  4. improved mucociliary function
  5. decreased microatelectasis
119
Q

Disadvantages of closed circuit or low flow circuit

A
  1. Rebreathing noxious gases (acetone, CO)

2. Increase risk PONV

120
Q

The rate of rise of the fractional concentration of inspired anesthetic (FI), initially follows which order kinetics?

A

First order

- rate of rxn depends on [ ] of one reactant

121
Q

Gas flow rate through the annular space of a conventional flowmeter is primarily affected by _____ at low fresh gas flow (FGF) rates

A

gas viscosity

  • laminar flow
  • Hagen-Poiseuille equation
122
Q

Gas flow rate through the annular space of a conventional flowmeter is primarily affected by _____ at high fresh gas flow (FGF) rates

A

gas density

  • turbulent flow
  • Graham’s law
123
Q

The (ascending / descending) bellows will CONTINUE to fill the ventilator chamber with a leak in the system

A

Descending

  • not reliable sx of leak
  • continue to fill with room air

*ascending bellows have advantage of providing a visual sx of a system leak

124
Q

(ascending/descending) bellows have advantage of providing a visual sx of a system leak

A

ascending

125
Q

When pts have decreased compliance (obesity, laparoscopic sx, pneumothorax, supine), they will need an increase in (pressure / volume)

A

pressure

126
Q

_____ will cause an abrupt drop in ETCO2 to zero on capnography

A

acute obstruction of ETT

Circuit disconnect

127
Q

_____ will cause a sudden drop in ETCO2, (value above zero)

A

Partial airway obstruction

Circuit leak

128
Q

When measuring blood flow velocity using doppler US, accuracy is significantly affected by _____.

A

the ANGLE btwn the US beam and the direction of blood flow velocity

129
Q

The higher the blood-gas solubility coefficient, the (faster / slower) the uptake in the blood

A

fastest

*the blood-gas coefficient is a representation of solubility of volatile anesthetics

130
Q

The uptake of volatile anesthetics is (directly / inversely) proportional to the rise in FA/FI.

A

Inversely

  • low solubility = faster onset
  • If there is quick uptake in the alveoli, there is less anesthetic available to create a [ ] gradient.
  • agents with lower solubility will have a lower uptake of anesthetic into the blood, more of a gradient available, faster onset
131
Q

Desflurane has a (high/low) blood-gas coefficient and therefore the lowest anesthetic uptake, and the FA/FI rapidly equilibrates and speed of anesthetic equilibration is rapid

A

lowest

132
Q

*the blood-gas coefficient is a representation of _____ of volatile anesthetics

A

solubility

133
Q

Isoflurane has a (high/low) blood-gas coefficient and therefore the highest anesthetic uptake, and the speed of anesthetic equilibration is slower

A

high

134
Q

Solubility from most to least for anesthetic gases

*Highly soluble drugs: larger uptake into blood: FA/FI ratio is lowered

A

Halothane > isoflurane > Sevoflurane > nitrous oxide > desflurane

135
Q

Why do certain dyes (methylene blue, indocyanine green, indigo carmine, nitrobenzene) show a falsely low oxygen saturation?

A

These dyes absorb light at 660 nm more than 940 nm.

- Pulse ox interprets this as greater [ ] of DEOXYHEMOGLOBIN (relative to oxyhemoglobin)

136
Q

What happens when a Line isolation monitor begins to sound (exceeds 2mA)?

A

Unplug the last item that was plugged in

- if it still goes off and you can’t ID source, cancel the elective case

137
Q

Pulse oximetry operates on the principle of the _____ law, which correlates [ ] with light absorption

A

Beer-Lambert law

138
Q

The intensity of light detected by infrared spectrophotometer is (directly / inversely) proportional to the CO2 partial pressure

A

INVERSELY

- A greater partial pressure of CO2, will absorb a greater amount of infrared light, thus less will reach the detector

139
Q

(Increased/Decreased) atmospheric pressure will result in an increased vaporizer output

A

DECREASED

- ie. moving from sea level (760 mmHg) to Denver (632 mmHg),

140
Q

Partial pressure or anesthetic potency of gases will (increase/decrease) with altitude

A

remain unchanged

141
Q

If you fill sevoflurane (lower vapor pressure 160 mmHg) into a vaporizer that is calibrated for isoflurane (higher vapor pressure 240 mmHg), you will have a (Higher / Lower) concentration of delivered gas

A

Lower vaporizer output

142
Q

The gauge pressure of nitrous oxide remains 745 PSIG (full) until approximately ____ % or ____ L of Nitrous oxide remains

A

16%

253L

143
Q

Examples of non-liquified gases (permanent gases that do NOT become liquid at room temp, even at very high pressures)

A

Oxygen
Air
Helium
Nitrogen

144
Q

Examples of Liquified gases (gases that become liquid at room temp when stored under pressure)

A

Carbon dioxide
Nitrous oxide
Propane

  • as gas is removed, liquid is vaporized to restore equilibrium, this is why the pressure gauge remains constant until the gas is nearly empty.
  • more reliable to determine amt left base on weight than pressure
145
Q

Nitrous oxide and Carbon dioxide

  • PSI of full cylinder
  • L of full cylinder
A

PSI of full cylinder

  • Nitrous oxide: 745 PSIG
  • CO2: 830 PSIG

L of full cylinder

  • Nitrous oxide: 1590 L
  • CO2: 1590 L
146
Q

Oxygen and Air

  • PSI of full cylinder
  • L of full cylinder
A

PSI of full cylinder

  • Oxygen: 1900 PSIG
  • Air: 660 PSIG

L of full cylinder

  • Oxygen: 1900 PSIG
  • Air: 660 PSIG
147
Q

The only type of fresh gas used in a closed circuit technique is ____

A

oxygen

- possible to maintain FiO2 < 30%, safe for head/neck surgery

148
Q

relative contraindications to closed circuit or low flow anesthetic techniques

A
  1. Sevoflurane (compound A)
  2. Alcohol intoxication (acetone intox)
  3. Manutrition (ketoacid intox)
  4. Heavy smokers (carboxyhemoglobin)
  5. Cirrhosis
  6. Ketoacidosis
149
Q

PLacement of the APL valve between the patient and the inspiratory valve can lead to _____

A

rebreathing

150
Q

3 requirements to avoid rebreathing of carbon dioxide in traditional circle system

A
  1. unidirectional valve must be positioned btwn pt and both inspiratory and expiratory limbs
  2. FGF cannot come into the circle system btwn the pt and expiratory valve
  3. APL valve cannot be positioned btwn pt and inspiratory valve
151
Q

The circle system can be used 3 ways depending on fresh gas flows:

A
  1. Semi-open
    - High FGF with no rebreathing
  2. Semi-closed
    - lower FGF with some rebreathing
  3. Closed
    - FGF matches pt consumption with complete rebreathing
152
Q

Rank vapor pressures of volatile anesthetics from greatest to least

*vapor pressure indicates substance is MORE likely to evaporate at a given temp than a substance with a lower vapor pressure

A

Desflurane > isoflurane > sevoflurane

Des: 681
Iso: 240
Sevo: 160

153
Q

mneumonic to help remember useful circuits for spontaneous ventilation

A

All Dogs Can Bite

A > D > C > B

154
Q

mneumonic to help remember useful circuits for controlled ventilation

A

Dead Bodies Can’t Argue

D > B > C > A

Anesthesia 101 (38 decks)

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