Peripheral Nerve Stimulator Flashcards

1
Q

nerve stimulator outline (6)

A

1-nerve electrically stimulated
2-ach released
3-ach binds nicotinic ach R
4- ach eventually degraded
5-prejunctional ach R allow choline and acetic acid to enter nerve again
6- choline and acetic acid form ach again

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2
Q

how long does each stimulus last?

A

0.2msec (200 microseconds)

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3
Q

Why wouldn’t you use stimulation durations of >500microseconds?

A

it would have the ability to cause direct muscle stimulation

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4
Q

when Ach binds to nicotinic R and the R arnt blocked what happens?

A

twitch occurs

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5
Q

when Ach binds to nicotinic R and the R are blocked what happens?

A

weaker twitch or no twitch occurs

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6
Q

what is Ach degraded into?

A

acetic acid and choline

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7
Q

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

A

prejunctional Ach R

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8
Q

weak muscle contraction

A

some of the R are blocked by muscle relaxant

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9
Q

zero muscle contraction

A

100% of R are blocked

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10
Q

reversing muscle paralysis with neostigmine

A

muscle relaxants and Ach competitively bind

junction being flooded with Ach then Ach overcomes muscle relaxant

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11
Q

reveral with neostigmine and there is too much muscle relaxant on board

A

wont be able to overcome the muscle relaxant

need some muscle function before neostigmine

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12
Q

reversal with sugammadex

A

binding and encapsulates muscle relaxant and removes it from junction
can reverse deeper levels of relaxation

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13
Q

what are the 5 types of nerve stimulation patterns?

A
single twitch
train of four
tetanus
post tetanic count
double burst stimulation
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14
Q

pulse duration

A

0.2msec

200microseconds

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15
Q

what are the two types of single twitch nerve stimulation

A
1 Hz (1 stimuation per second)
0.1 Hz (1 stimulation per 10 seconds)
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16
Q

describe train of four nerve stimulation

A

delivers 4 stimuli (0.2msec each) over 2 second period (2Hz)

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17
Q

what is the amount of time between stimuli for train of four

18
Q

if the person is unparalyzed what will TOF show?

A

four twitches

19
Q

tetanus

A

continuous nerve stimulation at 50-100Hz
floods junction with max Ach
sustained muscle contraction

20
Q

what is the time limit for tetanus?

A

5 seconds

very painful

21
Q

post tetanic count (PTC)

A

50Hz tetanus for 5seconds
3 second pause
single twitch stimulation at 1Hz

22
Q

Double burst stimulation (DBS)

A

two short tetanic stimulations separated by 750msec pause

23
Q

first stimulation DBS

A

3 impulses at 50Hz

24
Q

second stimulation DBS

A

2 options:
two impulses at 50Hz (DBS 3,2)
three impulses at 50Hz (DBS 3,3)

25
fade
ocurrs when nerve is stimulated multiple times in a row and partial blockade 1st twitch stronger than 2nd 2nd stronger than 3rd etc
26
what does fade mean for the ach stockpiles?
less ach is released with subsequent twitch stockpiles are more and more depleted muscle contraction smaller
27
absence of fade
equal amounts of ach released from nerve on all twitches
28
fade and depolarizers vs nondepolarizers
fade will occur with nondepolarizing block | fade will NOT occur with depolarizing (phase I) block
29
where do nondepolarizing muscle relaxants block?
presynaptic and postsynaptic Ach R
30
partial nondepolarizing block with fade explained
presyn Ach R blocked choline and acetic acid cannot get back in stockpiles diminish less ach available for repeated stimuli
31
how do the stockpiles of Ach get back to normal in partial nondepolarizing block?
nerve rest for short period of time
32
the greater the degree of muscle paralysis (from partial nondep block) means (4)
1-higher number of presyn R blocked 2- lower amount of ach released on back to back stimuli 3- higher degree of fade 4- longer the nerve will have to rest before stockpiles refill
33
where do depolarizing muscle relaxants block?
postsynaptic ach R
34
partial depolarizing (phase I) block
choline and acetic acid can rapidly reenter stockpiles will NOT diminish equal amounts of Ach available for repeated stimuli no fade observed
35
Will the twitches in a partial depolarizing (phase I) block be even in back to back stimulation? what about will they be the same height (strength) as before the block?
even twitches for partial | the height will be diminished when comparing before block and during block
36
what are the two things needed in order for fade to occur?
partial nondepolarizing block | nerve stimulated at relatively high frequency
37
what is the gold standard of assessment of recovery of neuromuscular blockade?
fade
38
If the patients fourth twitch is as strong as the first twitch what does that mean?
the patient has for sure adequately recovered from neuromuscular blockade
39
during the onset of a partial nondepolarizing block what will you see?
twitch height gradually decrease or fade away (TOF and single twitch)
40
during onset of a partial depolarizing block what will you see?
twitch height gradually decrease or fade away (TOF and single twitch) **no fade with each individual train of four pattern**
41
during recovery of partial nondepolarizing block what will you see?
fade with TOF but not single twitch stimulation (bc single isnt fast enough frequencies to deplete stockpiles)