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Patient Monitoring and Instrumentation > Peripheral Nerve Stimulator > Flashcards

Peripheral Nerve Stimulator Flashcards

1
Q

how long does each nerve stimulus last?

A

0.2 msec

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2
Q

when will a twitch or muscle contraction occur?

A

if receptors aren’t blocked

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3
Q

what plays a role in preventing stockpiles of Ach inside the nerve from being depleted?

A

prejunctional Ach receptors

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4
Q

what happens when 100% of the receptors are blocked (profound neuromuscular blockade)?

A

no muscle contraction occurs

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5
Q

which drug works by binding and encapsulating and taking the muscle relaxant out of the neuromuscular junction

A

sugammadex

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6
Q

what are the 5 types of nerve stimulation patterns?

A
  1. single twitch
  2. train of four
  3. tetanus
  4. post tetanic count
  5. double burst stimulation
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7
Q

2 types of single twitch nerve stimulation

A
  1. 1 Hz

2. 0.1 Hz

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8
Q

what is a 0.1 Hz single twitch nerve stimulation?

A

1 stimulation per 10 seconds

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9
Q

what is a 1.0 Hz single twitch nerve stimulation?

A

1 stimulation per second

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10
Q

how many stimuli does TOF deliver and over how long?

A

4 stimuli (0.2 sec each) over 2 second period (2 Hz)

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11
Q

most painful nerve stimulation

A

tetanus

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12
Q

what is the stimulation for tetanus?

A

50-100 Hz over 5 seconds or less

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13
Q

post tetanic count is a ____ tetanus that is applied for ____ seconds followed by a ____ second pause followed by ________ at 1 Hz.

A

50 Hz; 5 seconds; 3 second ; single twitch stimulation

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14
Q

two short tetanic stimulations separated by a 750 msec pause

A

double burst stimulation (DBS)

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15
Q

What is the FIRST tetanic stimulation in DBS?

A

3 impulses at 50 Hz

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16
Q

What is the SECOND tetanic stimulation in DBS?

A

2 options: 1. two impulses at 50 Hz

2. 3 impulses at 50 Hz

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17
Q

DBS 3,3

A

3 bursts at 50 Hz
750 msec pause
3 more bursts at 50 Hz

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18
Q

DBS 3,2

A

3 bursts at 50 Hz
750 msec pause
2 more bursts at 50 Hz

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19
Q

which nerve stimulation has the lowest stimulation frequency (1-10Hz) and longest stimulation duration

A

single twitch

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20
Q

which nerve stimulation has the faster stimulation frequency (2-100 HZ) but shortest stimulation duration?

A

TOF and tetanus

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21
Q

when a nerve is stimulated multiple times in a row __ can occur if the pt has a partial neuromuscular block

A

fade

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22
Q

What does seeing fade mean?

A

something is causing less Ach to be released from the presynaptic nerve with each subsequent twitch

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23
Q

what does it mean whenever we see that all the twitches have the same strength ( no fade) ?

A

an equal amount of Ach was being released from the presynaptic nerve on ALL the twitches

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24
Q

what do nondepolarizing muscle relaxants block ?

A

both presynaptic and postsynaptic Ach receptors

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25
Q

how do stockpiles of Ach get back to normal with a partial neuromuscular block?

A

the nerve needs to be rested for a short period of time without being stimulated

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26
Q

describe the 4 things that happen the greater degree of muscle paralysis

A
  1. higher # of prejunctional receptors that will be blocked
  2. the lower amt of Ach that’ll be released on subsequent back to back stimuli
  3. the higher the degree of fade
  4. the longer the nerve will have to “rest” before stockpiles of presynaptic Ach can be restored
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27
Q

what do depolarizing muscle relaxants block?

A

postsynaptic Ach receptors

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28
Q

when will you not see fade?

A

during partial depolarizing Phase I block

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29
Q

why is the twitch height decreased in partial depolarizing phase I block?

A

postjunctional receptors are still blocked

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30
Q

What are the two things needed for fade to occur?

A
  1. there must be a partial neuromuscular nondepolarizing block
  2. the nerve must be stimulated at a relatively high frequency
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31
Q

what is the gold standard for assessment recovery of NM blockade?

A

fade

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32
Q

when will a pt for sure be adequately recovered from NM blockade?

A

when the pt’s fourth twitch is as strong as the first twitch (no fade is present)

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33
Q

what happens during ONSET of partial nondepolarizing block?

A

twitch height gradually decreases w/ TOF and single twitch stimulation

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34
Q

what happens during ONSET of partial depolarizing block ?

A

twitch height gradually decreases with both TOF and single twitch but you wont see fade with each individual train of four pattern

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35
Q

when do you see fade during recovery of nondepolarizing block?

A

fade with TOF (NOT single twitch)

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36
Q

which nerve stimulation cannot differentiate between depolarizing and nondepolarizing block?

A

single twitch stimulation

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37
Q

which nerve stimulation(s) CAN differentiate between depolarizing and nondepolarizing block?

A

TOF, tetanus, post tetanic count, and double burst stimulation

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38
Q

when can you see twitches with sux?

A

during neuromuscular onset using single twitch stimulation

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39
Q

information about quantities (information that can be measured with numbers)

A

quantitative data

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40
Q

information that cannot measured or info about qualities

A

qualitative data

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41
Q

traditional nerve stimulators are more ____ (qualitative or quantitative)

A

qualitative

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42
Q

traditional nerve stimulators (SunMed brand) deliver maximum output current of how much?

A

70 mA

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43
Q

tetanus in a traditional nerve stimulator (SunMed) brand is ___ Hz.

A

100

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44
Q

the sun med plus brand you can choose between __ or __ Hz tetanus and has a ____ as an option

A

50 or 100; double burst stimulation

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45
Q

the StimPod is an example of ___

A

newer quantitative peripheral nerve stimulator

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46
Q

the StimPod can use which of the following nerve stim?

A

TOF, double burst, and post tetanic count stimulation

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47
Q

where should the negatively charged electrode be placed to achieve a maximal twitch height?

A

closest proximity to nerve

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48
Q

for the ULNAR nerve, where should the red and black electrodes be placed?

A

red should be proximal and black should be distal

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49
Q

for the facial nerve where should the negative electrode be placed?

A

over the temporal branch of facial nerve; red can be placed on forehead (zygomatic arch good landmark)

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50
Q

no motor units respond

A

subthreshold stimulus

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51
Q

one motor unit responds

A

threshold stimulus

52
Q

increasing number of motor units respond

A

submaximal stimulus

53
Q

all motor units respond

A

maximal stimulus

54
Q

AKA pre-relaxant control response

A

maximal stimulus

55
Q

all motor units respond

A

supramaximal stimuli

56
Q

what kind of stimulus current should anesthetists use for nerve stimulators?

A

supramaximal stimulus

57
Q

how do you determine the supramaximal stimulus current ?

A

using a SINGLE TWITCH stimulation and performing a single twitch every 1-10 seconds

58
Q

what is the current required for supramaximal stimulus?

A

40 mA

59
Q

what is the current required for supramaximal stimulus for the ulnar nerve for a 60 kg female pt?

A

30-40 mA

60
Q

what is the current required for supramaximal stimulus for the ulnar nerve for a very obese or large individual?

A

80 mA

61
Q

what current must be applied for supramaximal stimulus to the PERIPHERAL nerve?

A

50-80 mA

62
Q

An anesthetist should set the current _____ higher than what they observe the maximal stimulus to be.

A

10-20%

63
Q

what are the two problems with direct muscle stimulation?

A
  1. dosing more muscle relaxant when the pt is already profoundly paralyzed
  2. reversing muscle paralysis when the pt isnt ready
64
Q

why is direct muscle stimulation unlikely? (2)

A
  1. the pulse duration on our nerve stimulator is 200usec

2. the max current output on our nerve stimulators is usually 60-80 mA

65
Q

to ensure the current is supramaximal current while avoiding direct muscle stimulation, what should you turn the nerve stimulator up to?

A

max current output 70 mA

66
Q

Indications for single twitch nerve stimulation (3)

A
  1. satisfactory conditions for intubation (muscle relaxant onset)
  2. supramaximal stimulus
  3. post tetanic count (PTC)
67
Q

3 steps when using single twitch stimulation to determine muscle relaxant onset?

A
  1. anesthetist stimulates the nerve once every 1-10 seconds (0.1-1.0 Hz)
  2. muscle relaxant is administered
  3. once muscle relaxant takes effect, the twitch strength begins to gradually fade away (NOT FADE THOUGH)
68
Q

when does twitch height begin to decrease during a single twitch stimulation to determine muscle relaxant onset?

A

when 75% of the receptors are blocked

69
Q

what are the disadvantages to single twitch stimulation (3)?

A
  1. fade during recovery is not likely to be observed
  2. it cannot distinguish b/w depolarizing and nondepolarizing block
  3. limited use in assessing recovery from NM block
70
Q

this nerve stimulation pattern is an indication of how profound NM blockade is

A

TOF

71
Q

how many muscle twitches should a pt display prior to neostigmine reversal?

A

at least 2-3 muscle twitches

72
Q

0 out of 4 twitches

A

> 90% receptor block

73
Q

1/4 twitches

A

90% receptor block

74
Q

2 twitches

A

80% receptor block

75
Q

3 twitches

A

75% receptor block

76
Q

4 twitches

A

<75% receptor block

77
Q

T4:T1= 60% means..?

A

4th twitch is 60% as strong as the 1st twitch

78
Q

T4:T1= 100% means…?

A

4th twitch is just as strong as the 1st twitch

79
Q

3 outcomes of having a higher T4:T1 ratio

A
  1. stronger the 4th twitch will be compared to the 1st twitch
  2. lower the fade will be
  3. the stronger the muscle function
80
Q

TOF disadvantages (3)

A
  1. less useful in assessing partial DEPOLARIZING block
  2. its not quite as good at measuring deep levels of blockade
  3. its not as useful in assessing muscle relaxant onset
81
Q

which nerve stimulation can assess the deepest levels of blockade?

A

post tetanic count

82
Q

what is a great indicator that the pt’s muscle paralysis has been adequately reversed?

A

sustained tetanus for >5 seconds without fade

83
Q

in post tetanic count, a twitch before tetanus means?

A

less total Ach in the synapse (smaller contraction)

84
Q

in post tetanic count, a twitch after tetanus mean>?

A

more total Ach in the synapse (larger contraction)

85
Q

what predicts the time of recovery?

A

number of post tetanic twitches

86
Q

True/False: the lower the number of post tetanic twitches the longer the anesthetist will have to wait for a return of a single twitch.

A

TRUE .

87
Q

what indicates a residual block in DBS?

A

a decrease in second response; fade is more easily detected with DBS than TOF

88
Q

advantages of DBS (2)

A
  1. better indicator of fade than tetanus or TOF

2. less painful than tetanus

89
Q

what two factors effect the degree to which the NMJ is flooded with Ach by nerve stimulation patterns?

A
  1. stimulation frequency

2. stimulation duration

90
Q

what will happen if you stimulate a nerve right after the NMJ had been flooded with Ach?

A

produces stronger muscle contraction; UNDERESTIMATES the NM block making you think the pt is less paralyzed than they really are

91
Q

how often can DBS be repeated?

A

12-15 seconds

92
Q

how often can TOF be repeated?

A

10-30 seconds

93
Q

how often can tetanus be repeated?

A

2 minutes minimum time that should pass before repeating tetanus stimulation

94
Q

how often can PTC be repeated?

A

6 minutes

95
Q

best stimulation pattern for determining muscle relaxant onset

A

single twitch

96
Q

which muscle is soonest to recover from paralysis?

A

diaphragm

97
Q

which muscle twitches with ulnar nerve stimulation and is LAST to recover from paralysis?

A

adductor pollicis

98
Q

which muscle twitches with facial nerve stimulation?

A

orbicularis oculi

99
Q

What is the order of recovery of muscles from paralysis? (start with soonest to recover)

A
  1. diaphragm
  2. rectus abdominus
  3. laryngeal adductors
  4. orbicularis oculi
  5. adductor pollicis
100
Q

the most useful site for determining onset time for intubation

A

orbicularis oculi; facial nerve stimulation

101
Q

which muscle recovery provides the most confidence that the breathing muscles have recovered?

A

adductor pollicis

102
Q

stimulation at this point reduces PONV

A

median nerve/ P6 acupuncture point

103
Q

what is used during PONV prophylaxis? (current and type of nerve stimulation)

A

50 mA current over the median nerve using single twitch stimulation at 1 Hz.

104
Q

when can reversal of neostigmine be given?

A

display at least one of four possible muscle twitches

105
Q

how does LC dose neostigmine with 4 twitches w/o fade

A

start with =0-1 mg neostigmine

106
Q

how does LC dose neostigmine with 4 twitches w/ fade?

A

start w/ 1-2 mg neostigmine

107
Q

how does LC dose neostigmine with 2-3 twitches

A

start with 2-3 mg neostigmine

108
Q

how does LC dose neostigmine with 1-2 twitches

A

4-5 mg neostigmine

109
Q

what is the immediate reversal of RSI dose of Roc 3 mins after administration for sugammadex?

A

16 mg/kg

110
Q

what are the 6 indicators for adequate reversal?

A
  1. sustained head lift
  2. sustained tetanus
  3. tidal volume
  4. strong hand grip
  5. negative inspiratory force (NIF)
  6. TOF ratio
111
Q

what is a normal inspiratory force?

A

-50 to -100 cm/H20

112
Q

what is an adequate NIF for reversal?

A

-35 to -20

113
Q

TOF ratio >0.75 is equal to?

A

sustained tetanus and head lift for 5 seconds, an effective cough and NIG of -25 cm/H20

114
Q

TOF ratio of >0.9 mean?

A

patients can sit up unassisted and have normal pharyngeal function

115
Q

physiologic factors that prolong duration of muscle relaxants (6)

A
  1. hepatic and renal disease
  2. hypothermia
  3. increased age
  4. premature neonates
  5. acidosis
  6. myasthenia gravis
116
Q

electrolyte abnormalities that prolong duration of muscle relaxants (4)

A
  1. hypocalcemia and hypercalcemia
  2. hypomagnesemia and hypermagnesemia
  3. hypokalemia
  4. hypernatremia
117
Q

medications that prolong duration of muscle relaxants (4)

A
  1. antibiotic
  2. antiarrhythmic agents
  3. inhalational agents
  4. prior administration of sux prolong duration of nondepolarizing drugs
118
Q

what causes a phase II block? (2)

A
  1. larger than normal doses of sux (>6 mg/kg)

2. sux is doses repeatedly or run on an infusion

119
Q

what are the 3 awake extubation criteria?

A
  1. pt must be breathing spontaneously
  2. pt must be strong enough to breath adequately
  3. pt must be awake enough to protect their airway and avoid laryngospasm
120
Q

when is deep extubation ABSOLUTELY CONTRAINDICATED? 4

A
  1. full stomach
  2. GERD/hiatal hernia
  3. difficult airway/intubation
  4. airway edema
121
Q

relative CI for deep extubation

A
  1. obesity

2. pts with OSA

122
Q

extubation criteria for deep extubation? 3

A
  1. pt must be breathing spontaneously w/ adequate tidal volumes
  2. the pt must be truly deep (test by absence of coughing when deflating the cuff or absence of rxn with a foreceful jaw thrust)
  3. the pt must be thoroughly suctioned
123
Q

6 possibilities of post extubation hypoxia

A
  1. apnea
  2. bronchospasm
  3. atelectasis
  4. pulmonary edema
  5. inadequate reversal
  6. hypoventilation/oversedation
124
Q

tx for post extubation apnea

A
  1. jaw lift with mask
  2. jaw lift with mask and oral airway
  3. gentle positive pressure with oral airway in place
  4. LMA vs propofol/Sux
125
Q

tx for atelectasis

A

biPAP mask (higher positive pressure at inspiration)

126
Q

tx for pulmonary edema

A
  1. diuretics if the cause fluid overload

2. possible intubation vs. pressure support ventilation

Patient Monitoring and Instrumentation (24 decks)

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