Peripheral Nerve Stimulator

Question 1

nerve stimulator outline (6)

Answer 1

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

Question 2

how long does each stimulus last?

Answer 2

0.2msec (200 microseconds)

Question 3

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

Answer 3

it would have the ability to cause direct muscle stimulation

Question 4

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

Answer 4

twitch occurs

Question 5

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

Answer 5

weaker twitch or no twitch occurs

Question 6

what is Ach degraded into?

Answer 6

acetic acid and choline

Question 7

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

Answer 7

prejunctional Ach R

Question 8

weak muscle contraction

Answer 8

some of the R are blocked by muscle relaxant

Question 9

zero muscle contraction

Answer 9

100% of R are blocked

Question 10

reversing muscle paralysis with neostigmine

Answer 10

muscle relaxants and Ach competitively bind

junction being flooded with Ach then Ach overcomes muscle relaxant

Question 11

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

Answer 11

wont be able to overcome the muscle relaxant

need some muscle function before neostigmine

Question 12

reversal with sugammadex

Answer 12

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

Question 13

what are the 5 types of nerve stimulation patterns?

Answer 13

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

Question 14

pulse duration

Answer 14

0.2msec

200microseconds

Question 15

what are the two types of single twitch nerve stimulation

Answer 15

1 Hz (1 stimuation per second)
0.1 Hz (1 stimulation per 10 seconds)

Question 16

describe train of four nerve stimulation

Answer 16

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

Question 17

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

Answer 17

500msec

Question 18

if the person is unparalyzed what will TOF show?

Answer 18

four twitches

Question 19

tetanus

Answer 19

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

Question 20

what is the time limit for tetanus?

Answer 20

5 seconds

very painful

Question 21

post tetanic count (PTC)

Answer 21

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

Question 22

Double burst stimulation (DBS)

Answer 22

two short tetanic stimulations separated by 750msec pause

Question 23

first stimulation DBS

Answer 23

3 impulses at 50Hz

Question 24

second stimulation DBS

Answer 24

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

Question 25

fade

Answer 25

ocurrs when nerve is stimulated multiple times in a row and partial blockade
1st twitch stronger than 2nd
2nd stronger than 3rd
etc

Question 26

what does fade mean for the ach stockpiles?

Answer 26

less ach is released with subsequent twitch
stockpiles are more and more depleted
muscle contraction smaller

Question 27

absence of fade

Answer 27

equal amounts of ach released from nerve on all twitches

Question 28

fade and depolarizers vs nondepolarizers

Answer 28

fade will occur with nondepolarizing block

fade will NOT occur with depolarizing (phase I) block

Question 29

where do nondepolarizing muscle relaxants block?

Answer 29

presynaptic and postsynaptic Ach R

Question 30

partial nondepolarizing block with fade explained

Answer 30

presyn Ach R blocked
choline and acetic acid cannot get back in
stockpiles diminish
less ach available for repeated stimuli

Question 31

how do the stockpiles of Ach get back to normal in partial nondepolarizing block?

Answer 31

nerve rest for short period of time

Question 32

the greater the degree of muscle paralysis (from partial nondep block) means (4)

Answer 32

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

Question 33

where do depolarizing muscle relaxants block?

Answer 33

postsynaptic ach R

Question 34

partial depolarizing (phase I) block

Answer 34

choline and acetic acid can rapidly reenter
stockpiles will NOT diminish
equal amounts of Ach available for repeated stimuli
no fade observed

Question 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?

Answer 35

even twitches for partial

the height will be diminished when comparing before block and during block

Question 36

what are the two things needed in order for fade to occur?

Answer 36

partial nondepolarizing block

nerve stimulated at relatively high frequency

Question 37

what is the gold standard of assessment of recovery of neuromuscular blockade?

Answer 37

fade

Question 38

If the patients fourth twitch is as strong as the first twitch what does that mean?

Answer 38

the patient has for sure adequately recovered from neuromuscular blockade

Question 39

during the onset of a partial nondepolarizing block what will you see?

Answer 39

twitch height gradually decrease or fade away (TOF and single twitch)

Question 40

during onset of a partial depolarizing block what will you see?

Answer 40

twitch height gradually decrease or fade away (TOF and single twitch)
no fade with each individual train of four pattern

Question 41

during recovery of partial nondepolarizing block what will you see?

Answer 41

fade with TOF but not single twitch stimulation (bc single isnt fast enough frequencies to deplete stockpiles)