Depolarizing NMB - SCh

Question 1

binds to the alpha subunit of the postsynaptic nicotinic receptor and mimics ACh and causes the muscle cell membrane to depolarize

Answer 1

depolarizing NMB

Question 2

competes with ACh to bind with the alpha subunits to prevent the ion channel from opening and preventing the muscle cell membrane from depolarizing

Answer 2

nondepolarizing

Question 3

two acetylcholine molecules linked by acetate methyl groups

Answer 3

SCh

Question 4

what ACh receptors are affected by SCh

Answer 4

• cholinergic receptors at NMJ
• parasympathetic nervous system
• sympathetic ganglions
• muscarininc receptors in the SA node

Question 5

Why use SCh?

Answer 5

• rapid intubation

- desire for short duration of action

Question 6

Causes depolarization – initial contractions (fasciculations) — then paralysis – diffuses away from NMJ — repolarizes for later use

Answer 6

Phase I SCh Block

Question 7

• Fasciculations
• decreased single twitch
• NO FADE W TETANUS/TOF/DOUBLE BURST
• blockade enhanced by anticholinesterase
• rapid recovery, short duration of action

Answer 7

Characteristics of Phase I SCh block

Question 8

• FADE OF TETANUS/TOF/DOUBLE BURST
• posttetanic twitch
• prolonged duration
• reversible with anticholinesterase

Answer 8

Phase II SCh block

Question 9

SCh: You give a small dose of edrophonium (.1-.2 mg/kg) and block becomes weaker. Should you give remainder of reversal dose? Is this indicative of a phase I or Phase II block

Answer 9

Give remainder, Phase II block

Question 10

SCh: You give small dose of endrophonium (.1-.2 mg/kg), block becomes stronger. Should you give remainder of dose and is this indicative of phase I or phase II block?

Answer 10

Avoid additional dose and phase I block

Question 11

What is SCh metabolized by

Answer 11

plasma choinesterase at 80 mg/min

Question 12

what organ is responsible for SCh elimination

Answer 12

kidneys

Question 13

where is pseudocholinesterase produced

Answer 13

liver

Question 14

anticipated in patients with severe liver disease, pregnancy, malignancies, malnutrition, collagen vascular disease, and hypothyroidism

Answer 14

deficit of plasma cholinesterase

Question 15

these patients can decrease plasma cholinesterase activity up to 40%, but at term there is no prolonged effect due to the increase volume of distribution of blood (high plasma volume)

Answer 15

pregnant patients

Question 16

two genes dictate quality and quantity of plasma cholinesterase

Answer 16

atypical plasma cholinesterase

Question 17

96% homozygous for normal genes - SCh duration is?

Answer 17

5-10 mins

Question 18

3.96% heterozygous atypical - duration of SCh?

Answer 18

30 mins

Question 19

.04% homozygous for atypical genes- duration of SCh

Answer 19

3 hrs or more

Question 20

How can you test for issues with SCh metabolism

Answer 20

dibucaine

Question 21

Inhibits normal plasma cholinesterase activity by 80%

Answer 21

dibucaine number of 80

normal 5-10 min duration

Question 22

inhibits homozygous atypical activity by 20%

Answer 22

dibucaine number 20

duration 3 hrs or longer

Question 23

inhibits heterozygous atypical activity by 40 to 60%

Answer 23

dibucaine number 40-60

duration 30 mins

Question 24

causes a decrease in plasma cholinesterase activity

Answer 24

neostigmine and edrophonium (to a lesser degree)

Question 25

- anticholinesterase drugs used in insecticides - treatment of glaucoma - myasthenia gravis - chemo drugs like nitrogen mustard - metoclopramide

Answer 25

cause decrease in plasma cholinesterase activity

Question 26

tacrine (cognex), donepezil (aricept), rivastigmine (exelon), galantamine (razadyne)

Answer 26

anticholinesterase drugs used to treat alzheimer's and some forms of dementia that increase ACh levels in the CNS that may prolong SCh

Question 27

tachycardia muscle rigidity bradycardia prolonged relaxation hyperkalemia increased IOP fasciculations increased ICP myoglobinuria increased intragastric pressure MH histamine release sustained muscle contractions

Answer 27

complications of SCh

Question 28

what patients should you not use SCh with?

Answer 28

damaged muscle membranes, guillain-barre, crush injury, MVA, burns

Question 29

ED95 SCh

Answer 29

0.3 mg/kg

Question 30

intubating dose SCh

Answer 30

1 mg/kg | 1.5 mg/kg with pretreatment

Question 31

IM dose SCh

Answer 31

4-5 mg/kg

Question 32

Onset SCh

Answer 32

45 to 90 seconds

Question 33

Durations SCh

Answer 33

5-10 mins