Anesthesia Technologist Practice Exam

Which muscle relaxant should be avoided in patients diagnosed with atypical plasma cholinesterase?

1. Vecuronium

2. Succinylcholine

3. Rocuronium

4. Atracurium

The correct answer is: Succinylcholine

Succinylcholine should be avoided in patients diagnosed with atypical plasma cholinesterase due to its unique metabolism. Succinylcholine is a depolarizing neuromuscular blocker that is rapidly broken down in the body by plasma cholinesterase into inactive metabolites. In patients with atypical plasma cholinesterase, there is a genetic variant of the enzyme that leads to a slower metabolism of succinylcholine. Consequently, this can result in prolonged neuromuscular blockade, causing significant complications such as respiratory failure and prolonged paralysis. Understanding the metabolism of neuromuscular blocking agents is crucial in safely managing anesthesia. In contrast, other muscle relaxants such as vecuronium, rocuronium, and atracurium do not rely on plasma cholinesterase for their breakdown. Vecuronium and rocuronium are primarily eliminated by the liver and kidneys, while atracurium undergoes a mechanism of spontaneous degradation and ester hydrolysis that is less affected by cholinesterase activity. Therefore, they do not pose the same risk for prolonged effects in patients with atypical plasma cholinesterase.