A 63-year-old man who is being treated in a hospital for an exacerbation of chronic obstructive pulmonary disease has hypercapnic respiratory failure. He is sent to the critical care unit, where he is premedicated with muscle relaxant X and the proper sedative before being intubated. The patient is subsequently placed on mechanical ventilation, however he lasts longer than anticipated while apneic. Anesthesiology is consulted, and the neuromuscular blockade in the patient is evaluated by electrically stimulating a peripheral nerve four times quickly and watching the muscle reaction. The findings are displayed below when the operation is repeated 30 minutes later. Muscle relaxant X is most likely to be which of the following medications?

Question

A 63-year-old man who is being treated in a hospital for an exacerbation of chronic obstructive pulmonary disease has hypercapnic respiratory failure. He is sent to the critical care unit, where he is premedicated with muscle relaxant X and the proper sedative before being intubated. The patient is subsequently placed on mechanical ventilation, however he lasts longer than anticipated while apneic. Anesthesiology is consulted, and the neuromuscular blockade in the patient is evaluated by electrically stimulating a peripheral nerve four times quickly and watching the muscle reaction. The findings are displayed below when the operation is repeated 30 minutes later.  Muscle relaxant X is most likely to be which of the following medications?

Quizplus · Accepted Answer

Eductional Objective: When used for rapid-sequence intubation, succinylcholine is a quick-acting, depolarizing neuromuscular blocking drug that equalizes the decrease of all four twitches during train-of-four stimulation (phase I blockade). Long-term succinylcholine administration or usage in individuals with aberrant plasma cholinesterase activity results in the shift to a phase II (nondepolarizing) block, which is characterized by a gradual lessening of all four twitches.

A 63-Year-Old Man Who Is Being Treated in a Hospital