Which of the following is a depolarizing neuromuscular blocker used to break a laryngospasm?

• A. Lidocaine
• B. Succinylcholine
• C. Vecuronium
• D. Propofol

Answer: (B)

When a laryngospasm occurs, the airway remains obstructed because the vocal cords involuntarily close. The quickest way to relieve this is to rapidly relax the laryngeal muscles with a depolarizing neuromuscular blocker. Succinylcholine fits this need because it binds to nicotinic acetylcholine receptors at the neuromuscular junction and causes a rapid, sustained depolarization. This prevents further transmission of nerve impulses to the muscles, leading to immediate muscle relaxation of the airway structures. Its onset is very fast, usually within 30 to 60 seconds, and the effect wears off in a short period (roughly 5 to 10 minutes), which is ideal when airway management may be needed again soon.

Lidocaine can blunt airway reflexes but does not cause paralysis. A nondepolarizing blocker like vecuronium can also stop movement, but it has a slower onset and a longer duration, which is less suitable in an emergency where quick relief and rapid recovery are important. Propofol may help by deepening anesthesia and suppressing reflexes, but it does not depolarize the neuromuscular junction and therefore does not provide the rapid, complete paralysis needed to break the spasm.