6. NM blockade and paralysis

Question 1

clinical use of NM blockade

Answer 1

surgery
prevent muscle contractions
maintain muscle relaxation/ paralysis without deep general anaesthesia
cosmetic surgery

Question 2

what does the patient experience during NM blockade

Answer 2

slow methodical paralysis in Skm
extrinsic muscles of eye first, then small muscles of face, hands followed by muscles of pharynx, respiratory muscles last
individuals still experience pain

Question 3

sites of action

Answer 3

1. prevent synthesis: block Ch uptake- slow, no clinical use and slow to reverse, hemicholonium
2. prevent release- botulinum toxin, black widow spider venom
   3, block receptor activation- nicotinic receptor antagonist
3. increase reuptake- AchE inhibitor reverses NM blockade

Question 4

black widow spider venom

Answer 4

explosive Ach release- spasms, paralysis

Question 5

Botulinum toxin: bacteria

Answer 5

produced by bacterium Clostridium botulinum

Question 6

Botox clinical uses

Answer 6

cervical dystonia (NM movement disorder of head and neck)
blepharospasm: involuntary contraction of eye muscles
severe primary axillary hyperhidrosis: excessive sweating

Question 7

non-depolarising

Answer 7

nAchR antagonist

useful for surgery

Question 8

features of non depolarising block

Answer 8

high freq. stimulation causes tetanus with duration slightly longer than twitch
occupy without stimulating post-synaptic nACh receptors
additive effect of similar drugs
block is competitive
onset action 3-5 mins, duration typically 30+ min

Question 9

how do you stop non-depolarising antagonist

Answer 9

agents that depolarise muscle membrane
drugs that increase Ach release as some receptors are still active
reversed by anticholinesterase (neostigmine)

Question 10

Depolarising

Answer 10

nAchR agonist 
persistent activation of nAchR-> inactivation of vg sodium channels 
rapid onset of action (<1min) 
short duration (<5 mins) 
ideal for intubation, ECT, dislocations

Question 11

features of depolarising agonist

Answer 11

block preceded by muscle twitches
during block tension tetanus is depressed but doesnt fade
AchE do no reverse block
block summates with other depolarising drugs
drugs with weak curare like action antagonise block

Question 12

dual block

Answer 12

phase II depolarising block

in some individuals: assume characteristics of non-depolarising block

Question 13

nAChR agonist/ depolarising blocker drugs

Answer 13

suxamethonium, dexamethonium

Question 14

nAChR antagonist/ non-depolarising blocker drug

Answer 14

atracurium, vecuronium, gallamine

Question 15

ACh- esterase inhibitor (anticholinesterase)

Answer 15

phsyiostigmine, neostigmine

Question 16

non-depolarising tattoo facts

Answer 16

slower onset, longer duration
useful for surgery
reversible with anti AChE drugs

Question 17

depolarising tattoo facts

Answer 17

rapid onset and offset
short duration
useful for tracheal intubations, ECT, dislocations