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Gen Exam 2 > PNS Stimulator > Flashcards

PNS Stimulator Flashcards

1
Q

T/F
The Nerve stimulator is a comprehensive, all-encompassing assessment of muscle relaxation.

A

False
Highly subjective
prone to errors/misreading
its a tool, not the end all be all

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2
Q

Feeling for twitches vs. watching

A

feeling for the twitch is a more accurate assessment

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3
Q

What affects lead contact?

A

sweating
hair
edema/gross anasarca
wounds

anything that interferes with conduction of stimulating current

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4
Q

Adductor Pollicis Muscle
innervation

A

innervated by ulnar nerve

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5
Q

When stimulating the adductor pollicis muscle, we see…

A

thumb adduction/twitching

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6
Q

Which muscle group is a good indicator that upper airway muscle fxn has recovered?

A

Adductor pollicis muscle

thumbs UP for UPPER airway

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7
Q

Adductor pollicis muscles are sensitive to ___ and recovers (before/after) the diaphragm, laryngeal adductors and abd muscles.

A

NMB
after

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8
Q

T/F
If our adductor pollicis muscle TOF is 0/4, this is a good indicator the pt is no longer breathing on their own.

A

False
Addctr pollcs could be zero, but patient could be breathing

the addctr pollcs recovers AFTER the diaphragm, laryngeal adductors and abd muscles.

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9
Q

Adductor Pollicis muscle residual could indicate….

A

upper airway obstruction!

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10
Q

Do we see twitches return faster in the face or in the ulnar region?

A

Face twitches disappear faster, but they return quicker (than ulnar region)

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11
Q

Adductor pollicis lead placement

A
  1. palm up, relaxed
  2. leads are above ulnar nerve’s path
  3. black/distal lead @ level of wrist on ulnar surface of flexor crease
  4. second/proximal/red lead 1-2 cm more proximal; parallel to flexor carpi ulnaris tendon
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12
Q

Which color is the distal lead?

A

black

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13
Q

what color is the proximal lead?

A

red

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14
Q

what locations are part of facial nerve stimulation?

A

orbicularis oculi

corrugator supercilli

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15
Q

Orbicularis oculi
location
response

A

covers eyelid

NMB reponse similar to adductor pollicis (thumb)

eyelid squint

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16
Q

corrugator supercilli
location
response

A

covers eyebrow

similar to laryngeal adductors, but faster onset and recovery

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17
Q

What should we stimulate to assess good intubating conditions and profound blocks?

A

Eyebrows (corrugator supercilli)

(note: orbicularis oculi is better for intubation d/t its onset & recovery being more similar to the laryngeal muscles)

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18
Q

Cautions when using corrugator supercilli/eyebrow for TOF

A

it recovers FASTER than the upper airway & addctr pollicis (airway may still be paralyzed!!!)

Full twitches here do NOT indicate full strength has returned

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19
Q

T/F
4/4 twitches in the corrugator supercilli indicate full muscle strength has returned.

A

FALSE

cor.supercil recovers faster than the airway

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20
Q

T/F
TOF assessment is imprecise and subjective.

A

true

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21
Q

Facial Nerve lead placement

A
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22
Q

T/F
The diaphragm is (more/less) resistant to blockade. It requires ___ the dose to paralyze than the ____.

A

more resistant
needs 2x dose of addctr pollcs

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23
Q

T/F
a pt may have no twitches in thumb, but be breathing, coughing or moving their vocal cords.

A

True
diaphragm requires 2x the dose of paralytic to paralyze than the addctr polcs

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24
Q

___ and ___ are less sensitive to blocks than the adductor pollicis.

A

Laryngeal muscles
diaphragm

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25
Q

Which medication may alter the expected pattern of muscle recovery?

A

Succinylcholine

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26
Q

The face indicates when we can ___, but not when we can ___.

A

can indicate when to ETT

doesn’t indicate if we can ExTT

face twitches return faster than spont. breathing (laryngeal/diaphragm); pt may be apneic even if TOF 4/4 on face

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27
Q

T/F
Facial nerves paralyze faster but recover slower than peripheral nerves.

A

False
central paralyzes and recovers faster

(facial vs ulnar)

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28
Q

T/F
Complete recovery at the corrugator supercilli indicates full recovery at the adductor pollicis.

A

False
Can have full recovery of C.S. but incomplete recovery of A.P.

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29
Q

Posterior Tibial Nerve is good for which cases?

A

No access to face/arms
trauma
burns

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30
Q

Posterior Tibial nerve
location
response

A
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31
Q

Posterior Tibial Nerve is comparable to….

A

adductor pollicis (ulnar nerve/thumb)

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32
Q

Posterior tibial nerve lead placement

A
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33
Q

Peripheral nerve stimulator

A

stimulation of periph nerve and its response

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34
Q

Peripheral nerve stimulator delivers currents at…

A

0-70 miliamp (mA)

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35
Q

Peripheral nerve stimulator contains _________ to decrease resistance.

A

stimulating electrodes w/ silver-silver-chloride interface

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36
Q

P. Nerve stimulators use ____ current.

A

direct curent (DC)

current goes to and from
(instead of going in one direction)

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37
Q

What battery can we put in the PN stimulator?

A

9 volt

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38
Q

⭐️
T/F
The PNS is a quantitative measuring tool.

A

False
QUALitative

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39
Q

Why is the PNS assessment considered subjective and variable?

A

interpretation amongst providers

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40
Q

TOF assessment when giving succinylcholine

A

assess TOF after giving and before providing additional doses

Pt may have unknown pseudocholinesterase deficiency & if twitches don’t return, we won’t know what caused it

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41
Q

Limitation of surface electrodes

A

don’t always stimulate all nerve fibers

may take several mins until optimal effect

subject to resistance

-aren’t close to nerve
-improper placement
-obesity
-hair

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42
Q

Which has greater ability to stimulate all nerves?
surface electrodes
needle electrodes

A

needle

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43
Q

How much current and frequency can we use to asses TOF without inducing muscle fatigue?

A

0.1 Hz once Q10 secs
increase to brief tetanic stimulation, 50 Hz

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44
Q

___ Hz will cause sustained muscle contraction, known as ___. Fade will be (present/absent)

A

50 Hz
tetanus
no fade

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45
Q

Supramaximal PNS stimulation occurs at ___ Hz and causes…

A

> 70 - 200
muscle fatigue/fade

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46
Q

What contributes to the presence of fade on TOF?

A

muscle fatigue
(excessively high Hz and/or overly frequent TOF assessment)

47
Q

T/F
Increased frequency of stimulation can restrict blood flow to the area.

A

False

dont spam the button

48
Q

T/F
We can stimulate the nerve as desired without it affecting our assessment of block depth.

A

False
It can

Again…don’t spam the button

49
Q

Five main patterns of stimulation

A
50
Q

0.1 Hz means we stimulate every….

A

10 seconds

51
Q

Which pattern of stimulation is least precise?

A

single twitch

52
Q

Single twitch frequency range

A

0.1 Hz (1 stimulus every 10 secs)
1.0 Hz (1 stimulus per second)

53
Q

Single twitch requirements

A

needs baseline comparison (perform before giving paralytic)

54
Q

Can single twitch be used to determine recovery?

A

No
determines onset of a block but not recovery

55
Q

TOF
____ stimuli @ ___ Hz

A

4 repetitive stimuli at 2 Hz (2/sec)

56
Q

⭐️
Even with TOF 4/4, ___ receptors may be still be ____.

A

75%
blocked

TOF is not very accurate!

57
Q

Which type of NMB agent is associated with fade in TOF?

A

non-depolarizing

58
Q

minimum TOF to determine extubation readiness

A

TOFr >0.9

59
Q

T4/T1
definition

A

fade ratio
size of fourth twitch/size of first

60
Q

Fade ratio of 1.0 occurs when…

A

no muscle relaxant given

61
Q

Fade ratio of 0 occurs when…

A

full muscle relaxation. (4/0 = 0; went from from 4 to 0; fully relax)

62
Q

Can TOF detect a phase II block?

A

Yes!

63
Q

Your patient’s fade ratio is 0.5. What does this mean?

A

first 2 twitches are equal; 50% of twitches are equal

considered partial block

bottom example in picture

64
Q

T/F
TOF 3/4 twitches means the ratio is .75

A

No
Twitch height determines ratio, however, we cannot determine this by naked eye.

65
Q

What is the TOF ratio here?

A

0.40 or 40%
T4/T1

66
Q

What type of NMB?

A

nondepolarizing

67
Q

What type of NMB?

A

depolarizing
succinylcholine (phase I)

68
Q

No twitches but diaphragm might move
___% blocked

A

95

69
Q

___% blocked
1/4 TOF w/ relaxed abd muscles

A

90

70
Q

TOF
Pt can sustain head lift & hand grasp. What % blockage?

A

30
this does not guarantee pt won’t fall back asleep and become apneic

71
Q

Normal VC and TV are restored at ____% blockage.

A

70-75
accompanied by 4/4 TOF

72
Q

T/F
Fade is never exhibited with succinylcholine

A

False
Depends on phase
Phase II = fade

73
Q

Tetanic (TET) Stimulation is a sensitive indicator to…

A

residual NMB

74
Q

Tetanic (TET) Stimulation
how does it work?

A
75
Q

TET fades/fatigues at (full/partial/no) block.

A

partial

76
Q

Posttetanic Count (PTC)

A

helps predict with TOF twitches will return

1) 5 second, 50 Hz tetanic stimulus
2) 3 second break
3) single twitch stimuli @ 1 Hz. “PTC predicts”

77
Q

One of the best ways to use TET stimulation is…

A

in combination with TOF to assess for residual NMB

TOF could be 4/4, but a fade on TET shows residual NMB

78
Q

When should we use Posttet count (PTC)?

A

profound block with 0/4 TOF

“Use PTC for Profound”

79
Q

PTC
Less twitches in the single-twitch portion means that…

A

longer time until TOF response returns

(PTC: profound block; predicts TOF return
TET: test for residual block)

80
Q

PTC is used to guide ___ especially with ___.

A

reversal
sugammadex

81
Q

What effect does the tetanus of PTC cause?

A

-mobilizes Ach at prejunctional membrane
-more is available at endplate to get PT (post-tetanic) twitches

82
Q

Double Burst Stimulation (DBS)

A
83
Q

Double burst stimulation (DBS) has a (greater/lesser) muscle response than TOF.

A

greater

84
Q

In Double burst stimulation, fade is detected…

A

In partial blocks
-second burst
- if TOF ~0.6

85
Q

What causes muscle fasciculations

A

-pre jxnal action of suxx
-stimulating ACh receptor on motor nerves
-repetitive firing
-release NT

86
Q

recovery of Phase I block

A

suxx diffuses away from NMJ
metab by plasma cholinesterase

86
Q

Phase II block is caused by…

A

prolonged exposure of suxx in NMJ (infusion, repeated dosing)

87
Q

Phase I block twitches

A

4 equal twitches before giving and after administration

88
Q

Depolarizing block is characterized by…

A

Decreased twitch tension
no fade on tetanic or TOF(repeated stimulation)
No post-tet potentiation

89
Q

Phase I or II?
Symmetrical decreased in size of all responses to TOF

A

Phase I

90
Q

Phase I or II?
No fade

A

Phase I

91
Q

Phase I or II?
T4/T1 ratio is 1.0 until ALL twitches disappear together

A

Phase I

92
Q

Phase I or II?
TOF acts like NDMR

A

Phase II

93
Q

Phase I or II?
Fade develops in response to TOF

A

Phase II

94
Q

Phase I or II?
results from too much/repeated depolarizer

A

Phase II

95
Q

Which muscles face faster onset and recovery of blocks?

A

central muscles with good blood supply

96
Q

Upper airway muscles & pharynx behave as (central/peripheral) muscles at onset. Their recovery is (fast/slow) d/t to their (sensitivity/resistance) to NMB drugs)

A

central
slow recovery b/c they’re sensitive to NMB drugs

97
Q

ideal muscle to monitor during induction/intubation
why?

A

-orbicularis oculi
-more similar to central muscle
onset similar to laryngeal/diaphragm muscles

(note: the corrugator supercili is also good, but not as good b/c its onset & recovery is faster than the laryngeal muscles)

orbicularis is optimum for onset!

98
Q

most valuable stimulation pattern at induction
why?

A

TOF
disappearance of TOF corresponds to optimal intubation conditions
(use single twitch stimulation to allow max stimulation level)

99
Q

T/F
TOF 0/4 is needed for induction

A

False
not necessary for induction but it is for surgical conditions

100
Q

T/F
Using the adductor policis for TOF during maintenance of anesthesia can indicate good diaphragm paralysis.

A

False
Adductor policis may be 0/4 TOF, but the diaphragm may not be paralyzed.

The diaphragm is resistant to blocks. The adductor policis is more sensitive.

101
Q

Which site should be monitored during the maintenance of anesthesia?

A

orbicularis oculi
reflects diaphragm more closely

102
Q

Most useful measurements during profound NM block

A

PTC and TOF

103
Q

TOF should be at least ___ before administering NM antagonist

A

1 or 2
more is better! d/t waiting times for reversal agents to start working

104
Q

during reversal and recovery, which location should be monitored?

A

adductor policis (peripheral muscles)

face recovers faster than diaphragm/laryngeal muscles

105
Q

T/F
Head lift is considered subjective monitoring.

A

True

feeling and looking = subjective
hard numbers = objective

106
Q

Acceleromyography (AMG)
mechanism

A

ulnar nerve

measure acceleration of a muscle response –> ratio

TOFR based

107
Q

AMG requirements

A

thumb must be allowed to move (cannot tuck)

susceptible to pt movement

108
Q

drugs that can potentiate NMB action (7)

A

antiBx (aminoglycosides)
loop diuretics (furosemide)
mag sulfate
lithium salts
Ca Ch blockers
quinidine
procainamide

CALM People Love Questions

109
Q

Besides drugs, what can potentiate NMB drugs?

A

hypothermia

acid-base imbalance

110
Q

If residual NMB is not recognized and we extubate, what could happen?

A
111
Q

Evidence of inadequate NM recovery

A
112
Q

T/F
Sedatives should not be used when attempting to manage an extubation in the presence of residual NMB.

A

False
sedatives are part of the management plan

“you may have to sedate the pt as you try to wake them up” Dr Rogers

113
Q

Management of extubation w/ residual NMB

A

**can use LMA if pt not full stomach

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