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APEX ANESTHESIA FLASHCARDS > UNIT 6 Monitors & Equipment > Flashcards

UNIT 6 Monitors & Equipment Flashcards

1
Q

What components are present in the high pressure system of the anesthesia machine? What is the gas pressure in this region? How do you do a high pressure leak test?

A

begins at the cylinder & ends at the cylinder regulators.

components include:

  • hanger yoke
  • yoke block w/ check valves
  • cylinder pressure gauge
  • cylinder pressure regulators

The gas pressure is from the cylinder pressure

To do a high pressure leak test: close APL valve and pressurize the circuit to 30 cm H2O and observe the airway pressure gauge. The pressure should remain constant

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2
Q

What components are present in the intermediate pressure system of the anesthesia machine? What is the gas pressure in this region?

A

begins at the pipeline & ends at the flowmeter valve.

components include:

  • pipeline inlets
  • pressure gauges
  • ventilator power inlet
  • oxygen pressure failure system
  • oxygen second stage regulator
  • oxygen flush valve
  • flowmeter valve

gas pressure = 50psi (if pipeline) or 45psi (if tank)

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3
Q

What components are present in the low pressure system of the anesthesia machine? What is the gas pressure in this region?

How do you do a low pressure leak test?

A

begins at the flowmeter tubes & ends at the common gas inlet.

components:
- flowmeter tubes (Thorpe tubes)
- vaporizers
- check valves
- common gas outlet

gas pressure = slightly above atmospheric pressure

Low pressure leak test is also called the negative pressure leak test. It assesses integrity of low pressure circuit from the flow meter valves to the common gas outlet. The test is done by attaching bulb to common gas outlet and creating -65 cm H2O pressure

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4
Q

What are the 5 tasks of oxygen in the anesthesia machine?

A
  1. O2 pressure failure alarm
  2. O2 pressure failure device (failsafe)
  3. O2 flowmeter
  4. O2 flush valve
  5. ventilator drive gas (if pneumatic bellows)
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5
Q

Describe the pin index safety system.

A

PISS prevents inadvertent misconnections of gas cylinders

pin configuration on each hanger yoke assembly is different for each gas, making unintended connections of the wrong gas unlikely, but not impossible (>1 washer b/n the hanger yoke & stem of the tank may allow PISS to be bypassed)

air = 1,5
oxygen = 2,5
N2O = 3,5
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6
Q

Describe the diameter index safety system

A

DISS prevents inadvertant misconnections of gas hoses

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7
Q

What are the maximum pressures and volumes for the cylinders that contain air, oxygen, and N2O?

A

air (yellow): 1900psi, 625L

oxygen (green): 1900psi, 660L

N2O (blue): 745psi, 1590L
weight full = 20.7lb
weight empty = 14.1lb

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8
Q

The bourdon pressure gauge on an O2 cylinder reads 500psi. If the flow rate is 4L/min, how long will this cylinder provide oxygen?

A

full = 660L/1900psi

660L/1900psi = X/500psi = 174L
174L/4lpm = 43.5mins

some books use 2000psi

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9
Q

Is it ever safe to use an oxygen cylinder in the MRI suite?

A

not unless it’s made of nonmagnetic material such as aluminum.

An MRI safe cylinder will have two colors: most of the tank is silver and only the top is the color that signifies the gas it contains

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10
Q

List 3 safety relief devices that prevent a cylinder from exploding when the ambient temperature increases.

A

gas cylinders should never be exposed to temp >130F or 57 C = fire/explosion

  • fusible plug made of Woods metal (melts at elevated temperature)
  • frangible disk that ruptures under pressure
  • valve that opens at elevated pressures
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11
Q

Give 1 example of how the oxygen pressure failure device (failsafe) might permit the delivery of a hypoxic mixture.

A

the failsafe device checks pressure (not flow)

if there is a pipeline crossover, then the pressure of the new gas will provide the pressure to defeat the failsafe device & the patient will be exposed to a hypoxic mixture

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12
Q

Give 4 examples of how the hypoxia prevention safety device (proportioning system) might permit the delivery of a hypoxic mixture.

A
  1. oxygen pipeline crossover
  2. leaks distal to the flowmeter valves
  3. administration of a 3rd gas (helium)
  4. defective mechanic or pneumatic components
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13
Q

What is the difference b/n the oxygen pressure failure device and the hypoxic prevention safety device?

A

oxygen pressure failure device (fail safe device)
- shuts off an/or proportionately reduces N2O flow if O2 pressure drops below 20psi

hypoxia prevention safety device (proportioning device)

  • prevents you from setting a hypoxic mixture with the flow control valves
  • limits N2O flow to 3x the O2 flow (i.e. N2O max = 75%)
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14
Q

Describe the structure and function of the flow tube.

A

internal diameter of flow tube is narrowest at the base & progressively widens along it’s ascent

annular space = area b/n the indicator float & the side wall of the flow tube, also narrowest at the base & widest at the top.

laminar flow is dependent on gas viscosity (Poiseuille)
turbulent flow is dependent on gas density (Graham)

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15
Q

What is the safest flowmeter configuration on the anesthesia machine?

A

O2 flowmeter should always be furthest to the right

flowmeters are made of glass = the most delicate part of the anesthesia machine. A leak will allow O2 to escape the low pressure system –> delivery of hypoxic mixture

if a leak develops in any of the other flowmeters, it won’t reduce the FiO2 delivered to the patient

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16
Q

How do you calculate the FiO2 set at the flowmeter?

A

FiO2 = [ (21air flow rate) + (100oxygen flow rate) ] / total flow rate

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17
Q

An anesthesia machine uses fresh gas coupling. How do you determine the total Tv that will be delivered to the patient?

A

Vt on vent + FGF - volume lost to compliance

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18
Q

When using a ventilator that couples FGF to Tv, what types of ventilator changes will impact Tv delivered to the patient?

A

making nearly any change will ultimately impact the Vt delivered to the patient:

Vt increases with:

  • decreased rr
  • increased I:E ratio (1:2–> 1:1)
  • increased FGF
  • increased bellows height

Vt decreases with:

  • increased rr
  • decreased I:E ratio
  • decreased FGF
  • decreased bellows height
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19
Q

What is the vaporizer splitting ratio?

A

modern variable bypass vaporizers split fresh gas into two parts:

  1. gas that enters the vaporzing chamber & becomes 100% saturated w/ IA
  2. gas the bypasses the vaporizing chamber & doesn’t pick up any IA

before leaving the vaporizer, these two fractions mix & this determines the final anesthetic concentration exiting the vaporizer

by setting the concentration on the dial, you determine the splitting ratio

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20
Q

What is the pumping effect?

A

can increase vaporizer output

anything that causes gas that has already left the vaporizer to re-enter the vaporizing chamber can cause the pumping effect. This is generally d/t PPV or use of the O2 flush valve

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21
Q

compare and contrast the variable bypass vaporizer w/ the injector type vaporizer.

A

variable bypass
- flow over vaporization
- automatic temp compensation
- elevation compensation

injector (des)
- tec6, drager D
- dual circuit (fresh gas isn’t split)
- vaporized by heat, then injected into the fresh gas
- electronically heated to 39C
- no compensation for elevation

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22
Q

What does the O2 analyzer measure?

A

monitors O2 concentration (not pressure) and is the only device downstream of the flowmeters that can detect a hypoxic mixture.

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23
Q

What are 2 things you must do in the event of an oxygen supply line crossover?

A
  1. turn on the O2 cylinder
  2. disconnect the pipeline
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24
Q

Pressing the O2 flush valve exposes the breathing circuit to ___ O2 flow & ___ O2 pressure.

A

flow 35-75L/min

pressure 50psi (pipeline pressure

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25
Q

What are 2 risks of pressing the O2 flush valve?

A

barotrauma (if pressed during inspiration)

awareness (gas doesn’t contain IA)

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26
Q

Describe the function of the ventilator spill valve in relation to using the O2 flush valve

A

if O2 flush valve is pressed during inspiration, the patient will be exposed to flows of 35-75L/min and a pressure of 50psi.

If it is pressed during expiration, the excess flow will first fill the bellows then the rest is vented out the scavenger

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27
Q

compare and contrast VC & PC ventilation

A

VCV: delivers a preset Tv over a predetermined time. Since Tv is fixed, the inspiratory pressure will vary as the pt’s compliance changes. Inspiratory flow is constant during inspiration

PCV: present inspiratory pressure over a predetermined time. Since pressure & time are fixed, Tv & inspiratory flow will vary depending on pt’s lung mechanics. Tv goal may not be achieved.

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28
Q

A patient is receiving pressure controlled ventilation. What conditions can alter the Tv delivered to the patient?

A

decreased w/:

  • decreased compliance (pneumoperitoneum, trendelenburg)
  • increased resistance (bronchospasm, kinked ETT)

increased w/

  • increased compliance (release of pneumoperitoneum, T-burg to supine)
  • decreased resistance (bronchodilators, removing a/w secretions)
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29
Q

You notice that soda lime has become exhausted in the middle of a surgical procedure. What is the best action to take at this time?

A

You may be tempted to increased the MV. Although this removes a greater amount of CO2 from the body, it doesn’t prevent the pt from rebreathing CO2 & may lead to hypercarbia

Instead, if you can’t replace the CO2 absorbent, then you should increase FGF (convert circle system to semi-open system)

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30
Q

What is desiccation & how does it apply to soda lime?

A

water is required to facilitate the reaction of CO2 w/ the CO2 absorbent. The granules are hydrated to 13-20% by weight. When it is devoid of H2O, it is said to be desiccated.
- ethyl violet informs you about exhaustion but doesn’t provide info about H2O content of the absorbent

in the presence of halogenated anesthetics, desiccated soda lime = increase CO production (des > iso&raquo_space;> sevo) & compound A production (sevo)

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31
Q

List 7 ways to monitor for disconnection of the breathing circuit

A

4 ways to monitor for circuit disconnect: pressure, volume, EtCO2, vigilance

  • precordial stethoscope
  • visual inspection of chest rise
  • capnography
  • respiratory volume monitors
  • low expired volume alarm
  • low peak pressure alarm
  • failure of bellows to rise w/ an ascending bellows (not w/ descending or piston)
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32
Q

What are the OSHA recommendations regarding IA exposure for health care workers in the OR?

A

halogenated agents alone <2ppm
N2O alone <25ppm

together: <0.5ppm halogenated, <25ppm N2O

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33
Q

compare and contrast the 4 types of breathing circuits, and list examples of each.

A

open

  • no rebreathing
  • no reservoir
  • insufflation, simple mask, NC, open drop

semi-open

  • no rebreathing
  • reservoir
  • mapleson, circle system if FGF > MV

semi-closed

  • partial rebreathing
  • reservoir
  • circle system w/ FGF
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34
Q

What is the purpose of the unidirectional valves in the breathing circuit?

A

to ensure that gas moves in one direction

  • if a valve becomes incompetent, the pt will rebreathe exhaled gas
  • the definitive fix is to correct the valve
  • if this cannot be done, then a closed or semi-closed system should be converted to a semi-open system
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35
Q

Which Mapleson circuit is most efficient for SV? Which is best for controlled ventilation?

A

spontaneous: “All Dogs Bite”
- best = mapleson A (A > DFE > CB)
- worst = mapleson B

controlled: “Don’t Be Arrogant”
- best = mapleson D (DFE > BC > A)
- worst = mapleson A

Mapleson A requires FGF 20L/min for controlled ventilation

Bain is modified Mapleson D, to prevent rebreathing FGF 2.5x min ventilation

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36
Q

Describe the mapleson breathing circuits

A

A: FGF, reservoir, APL, pt
B: reservoir, FGF, APL, pt
C: B w/ shorter circuit
D: reservoir, APL, FGF, pt
E: no reservoir, just FGF, pt (aka Ayre’s T piece) 0 valves
F: APL, reservoir, FGF, pt (aka Jackson-Rees) 1 valve

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37
Q

What conditions decrease pulmonary compliance? How does this affect the peak pressure and plateau pressure?

A

Decreased pulmonary compliance is usually d/t a reduction in the static compliance (PIP & PP increase)

  • endobronchial intubation
  • pulmonary edema
  • pleural effusion
  • tension pneumo
  • atelectasis
  • chest wall trauma
  • abdominal insufflation
  • ascites
  • Tburg position
  • inadequate NMB
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38
Q

What conditions increase pulmonary resistance? How does this affect the peak pressure and plateau pressure?

A

Usually d/t a reduction in dynamic compliance (PIP increases, PP remains unchanged)

  • kinked ETT
  • endotracheal cuff herniation
  • bronchospasm
  • bronchial secretions
  • compression of the airway
  • foreign body aspiration
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39
Q

Describe the 4 phases of the normal capnograph

A 
phase I (A-B) = exhalation of anatomic dead space
phase II (B-C) = exhalation of anatomic dead space + alveolar gas 
phase III (C-D) = exhalation of alveolar gas
phase IV (D-E) = inspiration of fresh gas that doesn't contain CO2
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40
Q

Discuss the significance of the alpha and beta angles on the capnograph.

A

increased alpha angle = expiratory airflow obstruction: COPD, bronchospasm, or kinked ETT

beta angle is increased = in rebreathing

in the case of CO2 absorbent exhaustion, the beta angle remains normal, but the baseline increases

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41
Q

recall all of the abnormal CO2 waveforms you can (there are 9)

A
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42
Q

Think of all the causes of increased & decreased EtCO2 that occur as a result of changes in CO2 production

A

increased EtCO2 d/t increased production:

  • increased BMR (increased VO2)
  • MH
  • thyrotoxicosis
  • fever
  • sepsis
  • seizures
  • laparoscopy
  • tourniquet or clamp removal
  • NaHCO3 removal
  • anxiety, pain
  • shivering
  • increased muscle tone (post NMB reversal)
  • medication side effect

decreased EtCO2 d/t decreased production:

  • decreased BMR (decreased VO2)
  • increased anesthetic depth
  • hypothermia
  • decreased pulmonary blood flow
  • decreased CO, hypotension
  • pulmonary embolus
  • V/Q mismatch
  • medication side effect
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43
Q

Think of all the causes of increased & decreased EtCO2 that occur as a result of changes in alveolar ventilation or equipment malfunction.

A 
INCREASED EtCO2
decreased alveolar ventilation 
- hypoventilation
- CNS depression
- residual NMB
- COPD
- high spinal anesthesia
- NM disease
- metabolic alkalosis
- medication side effect

equipment malfunction

  • rebreathing
  • CO2 absorbent exhaustion
  • unidirectional valve malfunction
  • leak in circuit
  • increased apparatus dead space
DECREASED EtCO2
increased alveolar ventilation
- hyperventilation
- inadequate anesthesia
- metabolic acidosis
- medication side effect

equipment malfunction

  • ventilator disconnect
  • esophageal intubation
  • poor seal w/ ETT or LMA
  • sample line leak
  • airway obstruction
  • apnea
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44
Q

What wavelengths of light are emitted by the pulse oximeter? What law is used to make the SpO2 calculation?

A

2 wavelengths of light:

  • red light (660nm); preferentially absorbed by deoxyHgb
  • near infrared light (940nm); preferentially absorbed by oxyHgb

Beer-Lambert law is used; relates the intensity of light transmitted through a solution and the concentration of a solute within the solution

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45
Q

Which conditions impair the reliability of the pulse oximeter?

A

decreased perfusion (vasoconstriction, hypothermia, Raynaud’s)

dysfunctional Hgb (carboxyHgb, MetHgb, but NOT HgbS or HgbF)

altered optical characteristics (methylene blue, indocyanine green, indigo carmine, NOT fluorescein)

nonpulsatile flow (CBP, LVAD)

motion artifact (shivering, movement)

other (electrocautery, venous pulsation, NOT jaundice or polycythemia)

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46
Q

What factors affect the accuracy of the NIBP measurement?

A

ideal bladder length = encircle 80% of the extremity

ideal bladder width = 40% of the circumference of the patient’s arm

falsely increased BP:

  • BP cuff too small
  • BP cuff too loose
  • BP measured on extremity below the level of the heart

falsely decreased BP

  • BP cuff too large
  • BP cuff deflated too quickly
  • BP measured on extremity above the level of the heart
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47
Q

How does the site of measurement affect the BP reading?

A

as pulse moves from the aortic root toward the periphery, the SBP increased, DBP decreases, and pulse pressure widens. MAP remains constant

at the aortic root: SBP is the lowest, DBP is the highest, PP is the narrowest

at the dorsalis pedis: SBP is the highest, DBP is the lowest, PP is the widest

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48
Q

How does arm position affect the NIBP reading? How about when an arterial line is used?

A

If BP cuff > heart, BP will be falsely decreased
If BP cuff < heart, BP will be falsely increased

For every 10cm change, the BP changes by 7.4mmHg
For every 1inch (2.5cm) change, the BP changes by 2mmHg

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49
Q

What information can you learn from the arterial BP waveform?

A 
systolic BP = peak
diastolic BP = trough
pulse pressure = peak-trough
contractility = upstroke
SV = area under the curve
closure of aortic valve = dicrotic notch
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50
Q

Discuss damping and the interpretation of the high pressure flush test.

A

optimally damped: baseline is re-established after 1 oscillation

underdamped: baseline is re-established after several oscillations (SBP is overestimated, DBP is underestimated)

overdamped: baseline is re-established after no oscillations (SBP is underestimated, DBP is overestimated)
Causes can include an air bubble or clot in the pressure tubing or low flush bag pressure, loss of diacritic notch will tell you if it’s overdamped

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51
Q

How do you determine the appropriate distance to thread a CVC or PA cath?

A
  1. you must know the distance from the site of entry to the vena cava junction
  2. you must know the distance from the VC junction to where the tip of the catheter should be placed

insertion site –> RA junction:

  • SC = 10cm
  • R IJ = 15cm
  • L IJ = 20cm
  • femoral = 40cm
  • R median basilic = 40cm
  • L median basilic = 50cm

RA junction –> catheter tip

  • RA = 0-10cm
  • RV = 10-15cm
  • PA = 15-30cm
  • PAOP position = 25-35cm
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52
Q

What are the 3 waves and 2 descents on the CVP waveform? What does each one signify?

A

a wave = RA contraction
c wave = tricuspid valve elevation into RA (RV contraction)
x descent = downward movement of contracting RV
v wave = RA passive filling
y descent = RA empties through open tricuspid valve

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53
Q

How do the waves and descents on the CVP waveform correlate w/ the electrical events in the heart?

A

A wave = RA contraction, just after P wave

C wave = RV contraction, just after QRS

X descent = RA relaxation, ST segment

V wave = passive filling of RA, just after T wave begins

Y descent = RA empties through tricuspid valve, after T wave ends

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54
Q

What factors increase or decrease the CVP?

A

increase:
- transducer below the phlebostatic axis
- hypervolemia
- RV failure
- tricuspid stenosis or regurg
- pulmonic stenosis
- pHTN
- PEEP
- VSD
- constrictive pericarditis
- cardiac tamponade

decrease

  • transducer above phlebostatic axis
  • hypovolemia
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55
Q

What conditions cause loss of the a wave on the CVP waveform?

A

occurs when synchronized contraction of the RA is lost

  • afib
  • V pacing
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56
Q

What conditions cause an increased “a wave” on the CVP waveform?

A

large a wave is produced when the atria contracts and empties against high resistance

  • tricuspid stenosis
  • diastolic dysfunction
  • MI, ischemia
  • chronic lung dz –> RV hypertrophy
  • AV dissociation
  • junctional rhythm
  • V pacing (async)
  • PVCs
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57
Q

What conditions cause a large v wave on the CVP waveform?

A
  • tricuspid regurg
  • acute increase in intravascular volume
  • RV papillary m ischemia
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58
Q

How does the waveform change as the PA cath is guided into position? What are the normal pressures at each step?

A
  1. RAP 1-10mmHg (CVP waveform)
  2. RVP 15-30/0-8mmHg (larger, steeper waveform)
  3. PAP 15-30/5-15mmHg (“step up” in the waveform + dicrotic notch)
  4. PAOP 5-15mmHg (mirrors CVP waveform)
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59
Q

The tip of the PA cath should be positioned in West lung zone ___?

A

zone III
in this region, there is a continuous column of blood b/n the tip of the PAC & the LV. Since LVEDP reflects back through the pulmonary circulation, a tip positioned in zone III provides the most accurate LVEDP estimate.

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60
Q

What is the equation for mixed venous oxygen saturation?

A

SVO2 = SaO2- [VO2/(Q1.34Hgb*10)]

Q = CO 
VO2 = O2 consumption

normal = 65-75%

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61
Q

What conditions are associated with a decreased SvO2? How about an increased SvO2?

A

decreased d/t:

  1. increased consumption (stress, pain, thyroid storm, shivering, fever)
  2. decreased delivery (decreased PaO2, decreased Hgb, decreased CO)

increased d/t:

  1. increased delivery (increased PaO2, increased Hgb, increased CO)
  2. decreased consumption (hypothermia)
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62
Q

relate the phases of the cardiac action potential to the EKG

A

phase 0, depolarization (Na+ inward) = QRS

phase 1, initial repolarization (Cl- in, K+ out) = QRS

phase 2, plateau (Ca++ in, K+ out) = ST segment

phase 3, final repolarization (K+ out) = T wave

phase 4, resting phase (Na+ out) = end of T wave –> QRS

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63
Q

What region of the myocardium does each EKG lead monitor? What coronary arteries are monitored by each lead?

A

We commonly use 12 leads to look at the heart’s electrical activity from a variety of different angles. We can divide these leads into 3 groups:

  1. bipolar leads (3), I, II, III
  2. limb leads (3), aVR, aVL, aVF
  3. precordial leads (6), V1-V6
CxA = I, aVL, V5, V6 (lateral)
RCA = II, III, aVF (inferior)
LAD = V1-V4 (septum, anterior)
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64
Q

List the conditions that can cause L & R axis deviation

A

R axis deviation:

  • COPD
  • acute bronchospasm
  • cor pulmonale
  • pHTN
  • PE

L axis deviation

  • chronic HTN
  • LBBB
  • aortic stenosis or regurg
  • mitral regurg
65
Q

recite the heart block poem

A

if “R is far from “P” then you have a first degree

longer, longer, longer, drop then you have a Wenckebach

if some “P”s don’t get through then you have a Mobitz II

if “P”s and “Q”s don’t agree then you have a third degree

66
Q

What is the mechanism of action for each antiarrhythmic class (I-IV)? List examples of each.

A

I Na+ channel blockers:

IA; mod phase 0 depression, prolongs phase 3 repol

  • quinidine, procainamide, disopyramide

IB; weak phase 0 depression, shortened phase 3 repol

  • lidocaine, phenytoin

IC; strong phase 0 depression

  • flecainide, propafenone

II BB; slows phase 4 repol in SA node

  • esmolol, metoprolol, atenolol, propanolol

III K+ channel blockers; prolong phase 3 repol (increased QT), increased effective refractory period

  • amiodarone, bretylium

IV CCB; decreased conduction velocity via AV node

  • verapamil, diltiazem
67
Q

What EKG findings are consistent with Wolff Parkinson White syndrome?

A
  • delta wave caused by ventricular preexcitation
  • short PR interval
  • wide QRS complex
  • possible T wave inversion
68
Q

What conditions increase the risk of torsades de pointes?

A

Phenothiazines
methadone, droperidol, amio w/ hypokalemia
ICH
Type I antiarrhythmics
(low K+, Ca++, or Mg++)
Romano Ward and Timothy syndrome

69
Q

What is the treatment for torsades de pointes?

A

reversing the underlying cause and/or shortening the QT interval

  • magsulfate
  • cardiac pacing to increase HR will reduce the AP duration & QT interval
70
Q

List 5 indications for cardiac pacemaker insertion

A
  • symptomatic SA node disease
  • symptomatic AV node disease
  • long QT syndrome
  • dilated cardiomyopathy
  • IHSS
71
Q

What is the significance of the NBG pacemaker identification code?

A 
position I = chamber paced
position II = chamber sensed
position III = response to sensed event
position IV = programmability
position V = pacemaker can pace multiple sites
72
Q

How does atrial pacing affect the QRS complex? How about ventricular pacing?

A 
a-paced = no QRS change
v-paced = widened QRS
73
Q

What conditions increase the risk of failure to capture?

A

when the myocardium becomes more resistant to depolarization

  • hyper/hypokalemia
  • hypocapnia (affects K+ shift)
  • hypothermia
  • MI
  • fibrotic tissue buildup around pacing leads
  • antiarrhythmic medications
74
Q

How does the cerebral oximeter work? What value is considered a significant change from baseline?

A

utilizes near infrared spectroscopy to measure cerebral oxygenation (similar to SpO2)

  • doesn’t have the ability to detect pulsatile flow, thus it’s primarily a measure of venous oxyHgb saturation & oxygen extraction
  • decreased delivery –> increased extraction –> decreased venous Hgb sat
  • >25% change from baseline suggests a reduction in cerebral oxygenation
75
Q

Describe the different types of EEG waveforms.

A

beta

  • high frequency, low voltage
  • awake mental stimulation & “light” anesthesia

alpha

  • awake but restful w/ eyes closed

theta

  • 4-7 cycles/sec
  • GA & children during normal sleep

delta

  • <4 cycles/sec
  • GA, deep sleep, brain ischemia or injury

burst suppression
- GA, hypothermia, CPB, cerebral ischemia (esp if unilateral)

isoelectricity
- very deep anesthesia, death

76
Q

How do brain waves change during GA?

A
  • induction = increased beta wave activity
  • light anesthesia = increased beta wave activity
  • theta & delta waves predominate during GA
  • deep anesthesia produces burst suppression
  • 1.5-2MAC, GA = isoelectricity
77
Q

name 2 drugs that are likely to reduce the reliability of the BIS value

A

N2O (increases amplitude of high frequency activity & reduces amplitude of low frequency activity). This doesn’t affect the BIS value

ketamine increases high frequency activity –> can produce a BIS that is higher than the level of sedation/anesthesia would otherwise suggest.

78
Q

What is the difference b/n micro and macro shock?

A

macroshock: comparatively larger amount of current that is applied to the external surface of the body. Impedance of the skin offers a high resistance, so it takes a larger current to induce vfib

microshock: smaller amount of current applied directly to the myocardium. High skin resistance is bypassed, so takes smaller current to induce vfib

79
Q

What are the key threshold values for macroshock and microshock?

A

macro:
1mA touch perception
5mA max for harmless shock
10-20mA “let go” current
50mA loss of consciousness
100mA

micro:
10mcA max allowable current leak in the OR
100mcA vfib

80
Q

What is the role of the line isolation monitor? What should you do if it alarms?

A

assesses the integrity of the ungrounded power system in the OR. It tells ou how much current could potentially flow through you or a patient if a second fault occurs

  • primary purpose is to alert the OR staff of the first fault
  • does NOT protect you from macro/micro shock
  • will alarm when 2-5mA of leak current is detected
  • if alarm sounds, the last piece of equipment that was plugged in should be unplugged.
81
Q

A nondepolarizing block is characterized by several factors when assessed by a peripheral nerve stimulator. What are three of the factors?

A

1) Decrease in twitch tension
2) Fade during repetitive stimulation
3) Post-tetanic potentiation

(Got this from prodigy)

82
Q

What type of EEG activity would most likely be seen during the awake state?

A

High frequency, low voltage activity

83
Q

In an oxygen-driven ventilator, the amount of oxygen required to operate the ventilator is

A

Based off the minute ventilation of the patient

Also if your pipeline supply runs out: switch to hand bagging them

84
Q

According to U.S. Department of Transportation, the gas cylinder label must include:

A
  • Serial number
  • Date of last inspection
  • Type of metal used to construct cylinder
  • Max filling psi
  • Manufacturer/Owner
85
Q

Which monitor will be the first to detect an oxygen pipeline crossover?

A

Oxygen analyzer

86
Q

A negative deflection is observed on the airway pressure wave from when the mechanical ventilator is activated. Which mode of ventilation is the pt most likely receiving? (Select 2)

A. Controlled mandatory ventilation
B. Inverse ration ventilation
C. Biphasic positive airway pressure
D. Pressure support

A

Biphasic positive airway pressure and pressure support

A negative deflection before a breath indications a patient triggered breath. A machine initiated breath will only show a positive deflection

87
Q

Which situations would produce negative pressure inside the breathing circuit? (Select 2)

A. Tear in the bellows
B. OGT placed in trachea
C. Circuit disconnect
D. Malfunction of closed system scavenger

A

B. And D.

88
Q

What is the most likely cause of a lower than expected concentration of sevo inside the breathing circuit?

A. Bellows leak
B. Delivery at altitude
C. Tipped vaporizer
D. Pumping effect

A

Bellows leak- it allows gas to escape from circuit and there’s a risk of awareness

89
Q

Review the circle system and know where the valves are

A

Semi- open circuit: FGF exceeds minute ventilation

Semi-closed circuit: FGF is < 1 minute ventilation

Closed circuit: FGF is just enough to support pt’s O2 consumption

Disadvantages of circle system: unidirectional valves can malfunction:
- if it’s stuck open: rebreathing
- if it’s stuck closed: obstruction

90
Q

Advantages of mapleson circuit:

A
  • Less airway resistance so it’s good for peds
  • Convenient
  • Bain circuit prevents heat loss
91
Q

Disadvantages of mapleson circuits:

A
  • more apparatus dead space
  • requires high FGF to prevent rebreathing
  • loss of heat/humidity (except for Bain, it prevents heat loss)
  • unrecognized kinking seen in Bain circuit
92
Q

Bain circuit

A
  • tested with pethick test before use
  • inner tubing has FGF
  • outer tubing has exhaled gas (this is how incoming FGF is warmed)
  • prevents heat loss
  • disadvantage is inner tube is at risk of kinking/disconnection
  • modified mapleson D
  • can be used for spontaneous and controlled
  • to prevent rebreathing FGF should be 2.5x min ventilation
93
Q

Which component in the circle system protects the patient from excess airway pressure during SV?

A

The reservoir bag- it does it exceed internal pressure of 60 cm H2O if the bag is inflated 4x its size

94
Q

Which factors affect the extent of rebreathing exhaled gas in the circle system?

A
  • FGF
  • Arrangement of components in the circuit
  • Proper functioning of the unidirectional valves
95
Q

Benefits of mapleson circuit?

A. Low airway resistance
B. Allows rebreathing of exhaled gas
C. Simplicity of design
D. Minimal fresh gas requirement

A

A & C

Disadvantages: risk of rebreathing CO2 and there is a higher FGF requirement compared to a circle system

96
Q

Benefits of using low fresh gas flow in a circle system include:

A. Faster FA/FI equilibriation
B. Increased humidity in the system
C. Reduced risk of barotrauma
D. Slower reduction in body temperature

A

B & D

Lower FGF preserves humidity in the breathing system and slower reduction in body temperature

97
Q

What components are excluded from the mapleson circuit?

A. Unidirectional valves
B. APL valve
C. Carbon dioxide absorber
D. Reservoir bag

A

A & C.

No unidirectional valves or carbon dioxide absorber

98
Q

Dynamic compliance formula

A

Dynamic compliance = TV / PIP - PEEP

99
Q

What pulmonary compliance is a function of both airway resistance and elasticity of the chest wall?

A

Dynamic compliance

Static compliance is a function of elasticity only

100
Q

Compliance:

A

Change in volume / change in pressure

101
Q

Review this image

A
102
Q

What occurs with an increased PIP with no change in PP?
NEED TO KNOW THIS

A

Increased resistance

  • kinked ETT
  • bronchospasm
  • ETT cuff herniation
  • bronchial secretions
  • compression of airway
  • foreign body aspiration
103
Q

What is occurring here?

List of examples:

A

Increased PIP and PP: causing decreased compliance

  • Atelectasis
  • Endobronchial intubation
  • Pulmonary edema
  • Pleural effusion
  • Pneumo
  • Chest wall edema
  • Abdominal insufflation
  • Ascites
  • Trendelenburg
  • Inadequate muscle relaxation
104
Q

Mainstream in-line CO2 monitor:

A

Attached to ETT, faster, doesn’t require water trap or pumping mechanism, there is increased apparatus dead space

105
Q

Sidestream CO2 monitor

A

Slower, requires water trap to prevent contamination, has pumping mechanism

106
Q
A

Biphasic expiratory plateau
- occurs after single lung transplant
- second peak is the alveolar gas from diseased lung, air is trapped in it so longer time constant
- biphasic expiratory plateaus seen in severe kyphoscoliosis

107
Q
A
  • Metabolic acidosis (hyperventilation)
  • P.E. (Increased Deadspace)
  • Inadequate seal with LMA (equipment failure)

This waveform shows abnormally low EtCO2 which can result from reduced CO2 production, increased Deadspace, hyperventilation, or equipment failure

108
Q

Best SpO2 reading locations on body

A

Fast: Ear, nose, tongue, esophagus, forehead

Middle: finger

Slow: toe

109
Q

Pulse ox reads 80%, estimate the PaO2:

A

50 mmHg

110
Q

SpO2 80% = PaO2 mmHg?
SpO2 70% = PaO2 mmHg?

A

SpO2 90% = PaO2 60 mmHg
SpO2 80% = PaO2 50 mmHg
SpO2 70% = PaO2 40 mmHg

111
Q

Right or left shift in oxyhemoglobin curve?

Increased 2,3 DPG
Increased CO
Increased H+
Decreased pH

A

Right shift (occurs in metabolically active tissue)

112
Q

Right or left shift in oxyhgb curve?

  • decreased co
  • decrease H+
  • increase pH
A

Left shift (occurs in lungs)

113
Q

Pulse oximter is a useful monitor of:

A. Ventilation
B. Bronchial dilation
C. Anemia
D. Vascular compression

A

D. Vascular compression (think about Innominate artery compression during mediastinoscopy)

114
Q

Pulse oximeter is a noninvasive monitor of what 3 things

A

1) hemoglobin saturation BUT NOT ANEMIA OR VENTILATION
2) heart rate
3) fluid responsiveness

It can also assess perfusion

115
Q

Methomoglobin

Absorbs what two nm equally?

A

660 nm and 940 nm

The 1:1 absorption reads 85%.
It falsely underestimates SpO2 if O2 sat >85%
It falsely overestimates if SpO2 if O2 sat <85%

116
Q

Carboxyhemoglobin absorbs what nm?

A

660 nm same degree as oxyhgb, they will look the same on the pulse oximeter

117
Q

How do these affect pulse ox reliability

  • Hgb S and F
  • Jaundice
  • Fluorescein
  • Polycythemia
  • Acrylic nails
A

THESE DO NOT AFFECT IT

THINGS THAT DO: LVAD, CABG, Shivering, icg, methylene blue, vasoconstriction, Raynaud’s

118
Q

Most common method of measuring exhaled gases inside the breathing circuit?

A. Mass spectrometry
B. Raman scattering
C. Piezoelectric crystals
D. Infrared absorption

A

D. Infrared absorption

119
Q
A

PIP increase with unchanged plateau pressure: increased resistance

  • kinked ETT
  • bronchospasm
120
Q
A

Dysfunctional inspiratory unidirectional valve. Stuck in the open position leads to rebreathing exhaled CO2, this increases PaCO2 and etCO2 but the gradient becomes SMALLER

Where as venous embolism increases dead space and the gradient increases

121
Q
A

Carboxyhemoglobin bc it absorbs the same 660 nm light as oxyghemoglobin (pulse ox can’t distinguish between them)
Creating falsely increased SpO2 and overestimation of PaO2

Shivering and venous pulsation seen in tricuspid regurgitation can falsely reduce the SpO2

122
Q
A

Check the gas analyzer

This waveform represents sample line leak

123
Q

What is the most reliable monitor for detection of bronchial intubation?

A. Pulse ox
B. O2 analyzer
C. Chest auscultation
D. Capnograph

A

C. Chest auscultation

Key takeaway pulse ox and capnography are NOT reliable monitors to detect bronchial intubation

124
Q

Which monitors can be used to measure O2 concentration in the breathing circuit?

A

Clark electrode, paramagnetic analysis, or galvanic cell

INFRARED ABSORPTION SPECTROPHOTOMETRY CANT MEASURE O2

125
Q
A

Hemorrhage/hypovolemia = acute reduction in EtCO2

126
Q

Review how these correlate

A
127
Q

Central venous pressure is:

A. Falsely increased by placing the transducer above the zero point
B. Increased by PEEP
C. Decreased by pericardial tamponade
D. Unchanged by a VSD

A

B. Increased by PEEP

PEEP increases PVR

128
Q

CVP is a function of

A

Intravascular volume
Venous tone
RV compliance

Things that decrease CVP: transducer is above phlebostatic axis and hypovolemia

129
Q

Normal CVP in adult:
When do you measure it during respiratory cycle?

A

1-10mmHg

Measure CVP at end expiration

Things that increase it: PEEP, RV failure, tricuspid stenosis and regurgitation

130
Q
A

Tricuspid stenosis
Diastolic dysfunction

A wave correlates with atrial contraction, if a wave increases it is due to tricuspid stenosis or decrease compliance of the right ventricle (diastolic dysfunction), AV dissociation

131
Q

Large V wave on CVP:

A

Tricuspid regurgitation and RV papillary muscle ischemia

132
Q
A

When the tip enters the pulmonary artery:

The diastolic blood pressure increases and Diacrotic notch appears during pulmonary valve closure

133
Q

Review PA catheter

A

RAP is the same as CVP
RVP: 15-30/ 0-8 diastolic is equal to CVP
PAP: 15-30/ 5-15 diastolic rises and dicrotic notch forms
PAOP (wedge pressure): 5-15

Look at each range

134
Q

PA catheter

A

Review the waveform and values

PAOP reads pressures in the left atrium!

135
Q

When does pulmonary artery occlusion pressure overestimate left ventricular end-diastolic volume?

A. PA cath tip in west zone 3
B. PEEP
C. Diastolic dysfunction
D. Aortic insufficiency

A

PAOP overestimates LVEDV: PEEP and Diastolic dysfunction

PAOP underestimates LVEDV: Aortic insufficiency

136
Q

When would standard CO thermodilution method be used over continuous cardiac output?

When measuring CO with the thermodilution method what factors can overestimate CO?

What factors make it unable to predict CO?

A

CO standard thermodilution technique is used for a hemodynamic ally unstable patient

things that cause overestimation of CO:
- Low volume and too warm of injectate = overestimation of CO
- Partially wedged PAC
- Thrombus tip on catheter

Intracardiac shunt and tricuspid regurgitation = unable to predict effect on CO

137
Q

Factors that increased mixed venous oxygen saturation:

A. SNP
B. Thyroid storm
C. Sepsis
D. Anemia

name other things that increase mixed venous oxygen saturation:

A

SNP and sepsis

things that increase SvO2:
Increase O2 delivery:
- O2 therapy, increased hgb, increased CO

Decrease O2 consumption:
- hypothermia, cyanide toxicity

138
Q

Name things that decrease SvO2 mixed venous oxygen saturation:

A

Increased O2 consumption: stress, pain, thyroid storm, shivering, fever

Decrease O2 delivery: decreased SaO2, anemia

139
Q

2 conditions that limit reliability of the esophageal Doppler monitor:

A. Hypovolemia
B. Aortic valve disease
C. Aortic cross clamp placement
D. Esophageal disease

A

Alveolar valve disease and Aortic cross clamp

Other limitations: after CPB, pregnancy, and disease of thoracic aorta

140
Q
A

Reverse T burg

141
Q
A

Light anesthesia and anemia

SvO2 is reduced by things that increase O2 consumption or decrease O2 delivery

142
Q
A

Dorsalis pedis artery

Because systolic BP increases along the arterial tree

143
Q
A

22/9

Tip of PA cath is in the main Pulmonary artery
PAP Systolic range 15-30
PAP Diatolic range 5-15

144
Q

What is the most accurate measurement provided by oscillometric method of blood pressure measurement?

A. SBP
B. DBP
C. MAP
D. Pulse pressure

A

MAP

145
Q
A

Atrial systole and ventricular diastole

A wave is produced when the right atrium contracts to prime the right ventricle

146
Q
A

Aortic insufficiency

PAOP underestimates the LVED, so left ventricular volume is more than what is predicted by the PAOP

147
Q

Things that cause PAOP to overestimate the LVEDV include:

A

Myocardial ischemia

COPD

Left to right shunting

148
Q

What components of the CVP waveform correlate with ventricular systole?

What correlates with ventricular diastole?

A

C wave and x descent: ventricular systole

A wave and y descent: ventricular diastole

149
Q

What rhythm is this?

A

Wenckebach

2nd degree mobitz 1

Longer, longer, drop you have wenckebach

150
Q

What rhythm is this?

A

First degree block

R is far from P you have first degree

151
Q

What rhythm is this?

A

If some P’s don’t get through you have Mobitz 2

There is a p but no QRS

152
Q

What rhythm is this?

A

P’s and Q’s don’t agree you have 3rd degree

153
Q

Which heart blocks may need a pacemaker?

A

Second degree mobitz type 2 block

Third degree block

154
Q
A

Atrial- ventricular reentry

Most commonly seen in WPW is orthodromic AV nodal reentry and this is the one you can give lidocaine and adenosine

155
Q

Pt with WPW develops a.fib what is the best tx?

A

Procainamide + cardioversion and ablation

Only for antidromic AVNRT (wide) WPW, this one is more dangerous

156
Q

WPW orthodromic

A

More common

Narrow QRS

Can cardiovert, do vagal maneuvers, adenosine, BB, veramapil, amiodarone

Delta wave on the slope of R wave

Ablation is definite treatment for both types of WPW

157
Q

Things that can increase likelihood of torsades

A
  • hyperventilation, lasix, methadone, droperidol, bradycardia, zofran, hypomagnesia = prolong QT

Tx: mg and cardiac pacing

158
Q

What frequency would you use for superficial structure on U.S.?

A

> 10 mHz if it’s < 3cm below the skin

APEX ANESTHESIA FLASHCARDS (14 decks)

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