Acidosis and NMBs

Q: Acidosis may _______________ the effects of Neuromuscular blockades (NMBs)? - select one

A) prolongs

B) shortens

Answer: A

Metabolic and respiratory acidosis may prolong the effects of NMBs. This occurs via two mechanisms. First, the affinity of NMBs increases for postjunctional neuronal nicotinic acetylcholine receptors (nAChRs). Second, acidosis causes hypocalcemia which results in prolonging the effect of NMB. This effect becomes more pronounced as PH drops below 7.3. Conversely, with PH above 7.51, the effect of NMBs gets shortened mostly of nondepolarizing NMBs.

#pharmacology

#acidosis

References:

1. Waud BE, Waud DR. Interaction of calcium and potassium with neuromuscular blocking agents. Br J Anaesth 1980; 52:863.

2. Yamauchi M, Takahashi H, Iwasaki H, Namiki A. Respiratory acidosis prolongs, while alkalosis shortens, the duration and recovery time of vecuronium in humans. J Clin Anesth 2002; 14:98.