NMB | Clinical Question Bank

Question 1

After a single dose of a NDMR, recovery speed primarily depends on:

A. Redistribution
B. Hepatic elimination
C. Hoffman elimination
D. GFR function

Answer 1

A. Redistribution

Aft er a single dose of a NDMR, recovery speed primarily depends on redistribution, not (hepatic) elimination. Reduced elimination due to liver failure becomes signifi cant with repeated dosing or continuous infusion, when elimination speed determines block recovery time.

Question 2

Chronic condition like Liver cirrhosis pathologically increases the plasma volume and may affect the pharmacodynamic of AMINOSTERIOD NMB’s thru which of the following:

A. May result in slower neuromuscular block onset and increased dose requirement
B. May result in faster onset and decrease dose requirement
C. No dosing adjustment needed for Rocuronium
D. No significant change in onset but dose requirement is decreased

Answer 2

A. May result in slower block onset and increased dose requirement

Aminosteroid NDMRs are predominantly metabolized by the liver. Rocuronium undergoes only minimal metabolism and is mainly excreted unchanged. In early (alcoholic) liver failure, cytochrome P450 is induced, leading to faster metabolism of aminosteroid NDMRs. When liver dysfunction progresses, the metabolism of NDMRs is slowed down. Severe liver failure also aff ects plasma cholinesterase function, which may result in slower recovery from mivacurium- and succinylcholine-induced blocks.

Question 3

Hoffman elimination depends on which of the following:

A. pH and temperature
B. Liver function
C. GFR
D. Both A & C

Answer 3

A. pH and temperature

Hoff mann elimination depends on pH and temperature but is largely independent of liver and kidney function. Th e elimination half-life of cis-atracurium will not be signifi cantly changed in patients with liver failure, but electrolyte and acid–base imbalances and increased V d may still aff ect the onset and recovery of neuromuscular block

Question 4

The recovery speed of single-dose NMBAs depends on: redistribution, not elimination.

A. Redistribution
B. Hepatic elimination
C. Renal function
D. ED 50

Answer 4

A. Redistribution

The recovery speed of single-dose NMBAs depends on redistribution, not elimination.

Question 5

Aminosteroid NMBA metabolism speed is increased in early liver failure and decreased in severe liver failure.

Answer 5

TRUE

Question 6

Which NMB is relatively contraindicated to use on ESRD patients?

A. Pancorunium
B. Cis-atracurium
C. Rocuronium
D. Succinylcholine

Answer 6

A. Pancorunium

For pancuronium, excretion in the urine is the primary elimination route (65%). Severe kidney failure can dangerously prolong pancuronium’s T½β to several hours, causing an unpredictable duration of action and an increased risk of residual paralysis.

Question 7

Which of the following is a TRUE statement regarding the pathophysiology and/or anesthetic management of a myasthenia
gravis patient?

A) Presynaptic voltage-gated calcium channels are affected

B) Postsynaptic acetylcholinesterase breakdown is affected

C) Rocuronium dosage will likely need to be increased

D) Succinylcholine dosage will likely need to be increased

Answer 7

D. Succinylcholine dosage will likely need to be INCREASED

Succinylcholine dosage will likely need to be increased (1.5-2 mg/kg) for proper intubating conditions secondary to a decreased number of functional acetylcholine receptors.

Myasthenia gravis patients have autoantibodies against postsynaptic nicotinic acetylcholine receptors and will likely require increased succinylcholine dosage for intubating conditions. Lambert-Eaton (myasthenic syndrome) patients have IgG antibodies against presynaptic voltage-gated calcium channels and typically require decreased succinylcholine dosage. Both patients would require decreased dosages of nondepolarizing neuromuscular blockers.

Answer A: This disease is not to be confused with Lambert-Eaton myasthenic syndrome, which is characterized by IgG antibodies against presynaptic voltage-gated calcium channels. In Lambert-Eaton syndrome, succinylcholine dosage would likely
need to be decreased, as these patients are very sensitive to depolarizing and non-depolarizing muscle relaxants.

Answer B: Myasthenia gravis is an autoimmune disorder in which autoantibodies exist against the alpha-subunit of the muscle type nicotinic postsynaptic acetylcholine receptors, that causes neuromuscular transmission failure with associated muscle weakness and fatigue.

Answer C: Non-depolarizing muscle relaxant doses should be decreased

PEARLS:

Succinylcholine dosage for intubation will likely need to be increased in myasthenia gravis patients.
Neuromuscular blocks with succinylcholine or mivacurium are frequently prolonged

Reference: Miller’s Anesthesia | 9th edit