Neuromuscular Blocking Agents in Critical Care

Neuromuscular Blocking Agents

Neuromuscular blocking (NMB) agents are frequently used in the operating room (OR) as well as the intensive care units. The number of NMB agents available for use in these areas continues to increase. The clinician currently has 10 agents from which to choose, with another (rocuronium) soon to be available. NMB agents are classified as either depolarizing or nondepolarizing. Succinylcholine is the only depolarizing agent in clinical use today. It has the fastest onset of action of all NMB agents, but also the most adverse effects. The nondepolarizing agents as a group can be further differentiated by several characteristics: duration of action, cardiovascular effects, routes of metabolism/excretion, and cost. This allows an agent to be chosen based on patient parameters. Acetylcholinesterase inhibitors can be used to reverse residual neuromuscular blockade. The introduction of agents such as mivacurium, with a short duration of action, may reduce the need for acetylcholinesterase inhibitors; instead, neuromuscular function can be allowed to recover spontaneously. Finally, several factors must be considered when determining whether to add an agent to formulary: surgical case mix, patient acuity, agents currently on formulary, and cost of the new agent compared with those already on formulary.