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Monitors & Equipment > Apex- Miscellaneous Monitors (TOF/BIS/EEG/Electricity) > Flashcards

Apex- Miscellaneous Monitors (TOF/BIS/EEG/Electricity) Flashcards

1
Q

What is the BEST method of assessing a deep neuromuscular block?

A. Sustained tetany
B. Post-tetanic count
C. Double Burst Stimulation
D. TOF

A

B. Post-tetanic count

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2
Q

TOF delivers a series of 4 twitches over how many seconds
at how many Hz
with how many second intervals

A

2 seconds
2Hz
-0.5 secondintervals

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3
Q

Clinical recovery from NMB is achieved when the TOF ratio is > what

when is a reversal indicated with

A

> 0.9

< 0.9

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4
Q

Tetanus should be delivered over how many seconds at how many Hz

A

5 seconds
50Hz

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5
Q

DBS delivers two short bursts of _ Hz _ seconds apart

A

50 Hz
0.75 seconds apart

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6
Q

T/f: it is easier to detect fade with TOF compared to DBS

A

false - easier with DBS

think ur just comparing 2 instead of 4

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7
Q

TOF ratio of 0.9 = how many receptors still blocked?

A

75% blocked, 25% recovered

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8
Q

TOF wont be accurate for up to how long after tetanus assessment?

A

6 minutes

bc tetnus can cause post-tetanic potentiation
-flood the synaptic cleft with ACH that has been stored

its innacute bc ur testing the backup supply, now theres no acetylcholine to be had

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9
Q

A single twitch delivers a stimulus ranging from what to what Hz

A

0.1-1Hz

TOF = 2 hz

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10
Q

What % of Nm receptors must be blocked to lose T1

what does it mean to lose T1

A

90%

means there are no twitches

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11
Q

How many post-tetanic twitches suggest T1 will return at any moment

A

6-10

less than this suggests return of T1 is further away

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12
Q

Fade occurs when the T4/T1 ratio is less than what

A

1.0

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13
Q

What’s the advantage of DBS

A

it’s easier to detect fade with DBS than with TOF

but impairs TOF for up to 6 mins after

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14
Q

Select the statement that BEST describes cerebral ox

A. It’s invasive
B. a >/= 25% change from baseline suggests a reduction in cerebral oxygenation
C. It monitors arterial o2 sat in the cerebral blood
D. It monitors global cerebral oxygenation

A

B.

Cerebral ox is a noninvasive technique that uses near-infrared spectroscopy (NIRS) to measure regional (not global) cerebral oxygenation

based on the prinicple that decreased cerebral o2 delivery > increased cerebral o2 extration > decreased venous hemoglobin saturation

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15
Q

T/F: cerebral ox uses near infrared spectroscopy (NIRS)

what is it measuring

A

true

regional cerebral oxygenation (not global)

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16
Q

A change of what % or greater with cerebral ox suggests a reduction in CBF

A

25% or greater

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17
Q

Does cerebral ox measure arterial or venous o2 in the brain

A

venous

decreased o2 delivery = increased o2 exctraction = decreased venous hgb oxygenation

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18
Q

T/F- cerebral ox cannot detect pulsatile blood

A

true -

it measures venous o2 sat in the brain

measures venous oxyhemoglobin and o2 extraction

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19
Q

what equipment measures venous o2 sat in the brain

A

cerebral ox

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20
Q

What % of the blood in the brain is on the VENOUS side of ciruclation

A

75%

1 part artial, 3 parts venous

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21
Q

T/F: a decrease in cerebral o2 delivery will result in dereased o2 extraction

A

false

decreaed delivery will result in increased o2 extraction and decreased venous hgb sat

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22
Q

T/F- scalp hypoxia can be misinterpreted as brain ischemia

A

true

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23
Q

Rank the EEG waveforms from Highest to lowest frequency

Delta
Beta
Alpha
Theta

A
  1. Beta
  2. Alpha
  3. Theta
  4. Delta
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24
Q

Where does EEG provide information regarding electrical activity

what does it not provide great info about

A

in the cerebral cortex

subcortical structures, spinal cord, or peripheral nerves

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25
Q

During anesthesia, the EEG waveforms typically change in what 2 ways:

A
  1. they become slower (lower frequency)
  2. they become taller (higher amplitude)

slow, low > freak out big peak > slow, low > freak out big peak

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26
Q

anesthesia causes EEG waves of (higher/lower) frequency and (higher/lower) amplitude

A

lower frequency
higher amplitude

slow, low > freak out big peak > slow, low > freak out big peak

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27
Q

How does nitrous alone affect EEG

A

increae beta activity

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28
Q

which inhalational gent can increase epileptiform EEG activity

A

sevo

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29
Q

T/F: etomidate is not associated with epileptiform EEG activity

A

True

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30
Q

How does ketamine effect EEG activity

A
  • confuses it, may falsely increase activity
  • pt deeper than they appear on EEG
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31
Q

Burst suppression occurs with what 2 things

A

deep anesthesia and hypothermia

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32
Q

what EEG waveform is suggestive of cerebral ischemia

A

UNILATERAL burst suppression

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33
Q

Complete EEG supression (isoelectricity) occurs what what MAC

A

1.5-2 MAC

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34
Q

when would EEG monitoring be useful

3 examples

A

when cerebral oxygenation is at risk

CEA, deliverate hypotension, barbituate coma

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35
Q

Which brain waves occur in an awake but restful state with eyes closed

A

alpha

8-12 cycles/sec

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36
Q

label

A
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37
Q

T/F: induction of GA is associated with increased beta wave activity

A

True

beta waves = awake waves , high freq, low voltage
just think of it as the SNS stage 2 freakout before they actually go to sleep

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38
Q

Which kind of brain waves predominate during GA

A

Theta and Delta

Theta = 4-7 cycles /sec
Delta = < 4 cycles per sec (can also be assoc with brain ischemia or injury)

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39
Q

The development of what kind of waves during anesthetic maintenance might signify that the brain is at risk for ischemia

A

new delta waves

40
Q

what 3 circumstances can mimic cerebral ischemia

A
  1. deep anesthesia
  2. hypothermia
  3. hypocarbia
41
Q

Alpha, Beta, Theta, or Delta waves:

Light anesthesia

A

Beta

42
Q

Alpha, Beta, Theta, or Delta waves:
Normal sleep in kids

A

Theta

43
Q

Alpha, Beta, Theta, or Delta waves:
Deep sleep

A

Delta

44
Q

Alpha, Beta, Theta, or Delta waves:
Mental stimulation

A

Beta

45
Q

Alpha, Beta, Theta, or Delta waves:
GA

A

Theta and Delta

46
Q

Alpha, Beta, Theta, or Delta waves:
Brain ischemia

A

Delta

47
Q

Alpha, Beta, Theta, or Delta waves:
Awake

A

Beta

48
Q

T/F: Ketamine falsely elevates the BIS value

A

True

49
Q

Burst suppression begins at a BIS value of what

A

20

50
Q

T/F: there is no lag time between measuring EEG and computing the BIS value

A

False: 20-30 second lag

some people argue that titrating your anesthetic to the BIS is akin to driving using only your rear view mirrow

51
Q

BIS target for GA vs Patient safety index target for GA

A

BIS = 40-60
PSI = 25-50

both measure EEG, run data through an algorithm, and display a number to indicate the level of anesthetic depth

52
Q

What is the bispectral index monitor and how does it work?

A

BIS - uses a computer algorithm that translates raw EEG data into a number between 0-100

53
Q

BIS number of what = moderate sedation

A

80

54
Q

BIS deep hypnoti state number

A

40

GA 40-60

55
Q

4 things that influence BIS

A
  1. hypothermia
  2. EMG interference (increased muscle tone)
  3. encephalopathy
  4. ketamine
56
Q

T/F- as a sole agent, nitrous oxide does not reduce the BIS reading

A

true

57
Q

how does nitrous affect high frequency vs low frequency activity

BIS

A

increases amplitude of high freq activity
reduces amplitude of low freq activity

58
Q

T/F: ketamine increases low frequency activity

A

False - increases high frequency activity

can produce a BIS value that is higher than the level of sedation/anesthesia one would otherwise suggest

59
Q

T/F: BIS is less accurate in kids

A

True

60
Q

Select the statement that MOST accurately describes the function of the line isolation monitor:

A. If a piece of equipment becomes grounded, it cuts off the power supply to that piece of equipment
B. It protects the patient from microshock
C. The alarm sounds when the OR power supply becomes grounded
D. It isolates electrical equipment from the ground

A

C

61
Q

T/F: the electrical supply in the OR is NOT grounded

A

TRUE

the line isolation monitor is to alert the OR staff when the power supply becomes grounded
>an issue bc a second electrical fault can lead to an electric shock

62
Q

T/F: The line isolation monitor protects the patient from microshock

A

False

Line Isolation monitor

the line isolation monitor is to alert the OR staff when the power supply becomes grounded
>an issue bc a second electrical fault can lead to an electric shock

63
Q

T/F: The line isolation monior isolates the electrical equipment from the ground

A

False

Line isolation monitor

the line isolation monitor is to alert the OR staff when the power supply becomes grounded
>an issue bc a second electrical fault can lead to an electric shock

64
Q

T/F: the line isolation monitor cuts off the power supply to a piece of equipment that has become grounded

A

False

Line isolation monitor

the line isolation monitor is to alert the OR staff when the power supply becomes grounded
>an issue bc a second electrical fault can lead to an electric shock

65
Q

The OR power supply (is/is not) grounded and the equipment (is/is not grounded)

A

power supply = grounded
equipment = not grounded

on the first fault, the OR power supply becomes grounded - no completed circuit, no shock
second fault - circuit is complete and electric shock occurs

66
Q

The line isolation monitor assesses the integrity of hte (grounded/ungrounded) power in the OR

A

the ungrounded power system

67
Q

The line isolation monitor alarms if the sum of all currents exceeds what

what should you do if it alarms?

A

2-5mA

unplug the last piece of equipment that was plugged in (most common reason why it alarms)

68
Q

Max allowable current leak in the OR

A

10 MICROamps

microshock voltage for vfib is 100 MICROAMPS; so the allowable current leak is ssignifiantly lower

69
Q

Macroshock for VFIB

microshock

why are they different?

A

100mA

100 MICROAMPS

bc the surface of the skin offers a high resistance, so it takes a larger current to induce vfib
microshock is a current applied directly to the myocardium- no skin to be bypassed, a lot less voltage needed

70
Q

Macroshock vs microshock

A

macroshock = current applied to outside of body
microshock - current applied directly to myocardium

skin offers high resistance, so larger current is required for macroshock

71
Q

threshold for touch perception of electrical shock

max current for a harmless electrical shock

“let go” current before sustained contraction

A

1mA

5mA

10-20mA

72
Q

what voltage does LOC occur at

A

50mV

73
Q

For an electric shock to occur in the OR, there must be how many faults in the system

A

Two

After the first fault, the OR power supply becomes grounded. There is no completed circuit and no shock
After the second fault, the circuit is complete and electric shock occurs

-when your at home, an electric shock can occur with teh first fault since the power outlet is already grounded , the circuit is complete and electric schok occurs

74
Q

What is required to supply ungrounded power to the OR

A

an isolation transfomer

conceptually, you can think of this as a device that sits between the power coming from the power company and the OR

75
Q

T/F- the isolation transformer can tell usif theres a problem

A

false - the line isolation monitor is needed to assess the integrity of the ungrounded power system

76
Q

Does the LIM protect you from macro or microshock

A

no- neither - it’s primary purpose is to alert the staff of the first fault, meaning OR has become grounded, and if a second fault occurs, someone could get electrocuted

77
Q

Max allowable current leak in the OR vs when the LIM will alarm

A

max leak = 10 milliamps
LIM alarms at 2-5mA

*all electrical devices leak a small amount o current but if the sum of all the currents exxceeds 2-5mA, the alarm will sound,

78
Q

Do central lines and PACs increase the risk of microshock or macroshock

A

microshock- direct line to the heart, only 100milliaps required to produce vfib compared to 100mA for microshock thru the skin

79
Q

T/F: the return pas (bovie pad) grounds the patient

A

NO - grounded the patient is bad
gounded pt = complete circuit = shock

80
Q

What happens if the return pad fails

A

pt is at risk for burns

if too small or doesnt make good contact with skin- the current will find another way to exit the body > EKG pads/Jewelery/temp probes or anything else with conductive properties

81
Q

Why doesnt the bovie/electrocautery unit (ESU) provide a risk of vfib?

A

bc it uses a high-freuqency current that have low tissue penetration and dont affect excitable cells

500,000 - 1 million Hz

used to cut, coagulate, dissect, or destroy tissue

so they can destroy tissue but not penetrate it well? sure

82
Q

what does the return pad actually do?

A

It provides an exit point for the current by providing a low impedance surface area for the electrical current to exit the body thru and return to the generator

83
Q

Why is there no need for a return pad if using a bipolar ESU

A

bc the electrical current is not dispersed throughout the patient’s body since the ESU (forcepts) contain the active and return electrodes

84
Q

Why shouldn’t the bovie return pad be placed over bony porminences or metal implants

A

bc it needs to be in direct contact with the patietn’s skin to prevent burns

85
Q

what are the risks associated with the presence of body jewelry when the ESU is in use

A

it can cause a burn by reconcentrating the electrical current from the ESU

86
Q

what if the pt has a piercing on the right that wont come out and surgery is being done on the left- where should hte bovie pad be placed

A

on the left - dont place it in a place wehre jewelry would be in the direct path

87
Q

T/F: if somone cant get their metal jewelry out, they could use a capacitive-coupled return electrode instead

A

FALSE - this increases the burn risk

88
Q

If jewelry cont come out, it should be taped to the skin so that the largest surface area of contact esists between the jewelry and the skin

A

True

ex. belly button ringshould be taped flat agaisnt skin

this ocnfuses me

89
Q

if somone tells you they cant get their jewelry out, what are your thoughts

A
  1. are we using bovie
  2. where is the jewerluy in relation to the surgical site
  3. place the return pad away from it
  4. tape it
90
Q

What is the real name for the “grounding pad”

A

the return pad or return electrode

91
Q

why is the return pad so large?

A

bc a large, low impedance surface area is needed for the electrical current to exit the body and return to the power generator

92
Q

When assessing train-of-four, what degree of post-junctional nicotinic receptor blockade is consistent with teh disappearance of T4?

A

80%

93
Q

Cerebral oximetry:

A. Requires pulsatile flow
B. Measures venous oxygen saturation in cerebral blood
C. Monitors global cerebral oxygenation
D. Is an invasive monitoring technique

A

B.

uses near infrared spectroscopy (NIRS)

decreased o2 delivery = increased o2 extraction = decreased venous hgb sat

> /= 25% change from baseline = concern

94
Q

Match: Voltage, current, and impedance with:

CO, BP, and SVR

A

Voltage = BP
Current = CO
Impedance = SVR

95
Q

What is the minimum macroshock current required to produce vfib (enter answer in mA)

What about minimum microshock and answer in microamps

A

100mA

100 microamps

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