Brief review: Nondepolarizing neuromuscular blocking drugs and critical illness myopathy

Critically-ill patients who receive nondepolarizing neuromuscular blocking drugs (NMBDs) may be at risk of developing profound muscle weakness that may last for months after the NMBD is discontinued, especially when large cumulative doses of NMBDs and corticosteroids are co-administered to septic, mechanically ventilated patients. This review focuses on the etiology and clinical features of critical illness myopathy (CIM), summarizes specific risk factors for its development, and discusses strategies that might be used to attenuate or even prevent the development of this potentially devastating syndrome.

The etiology of CIM is unknown. Whether it can develop in at-risk patients who undergo lengthy operations during which they receive NMBDs is also unknown. In some patients following exposure to NMBDs their motor systems are impaired secondary to loss of thick (myosin) filaments that render the muscle unexcitable to direct electrical stimulation, while the sensory system is spared. Management of patients who develop NMBD myopathy is supportive, consisting of nutritional support, physical therapy, and daily trials of decreased ventilatory support.

Recent guidelines recommend that NMBDs be used in critically ill patients only when absolutely necessary, that the depth of muscle paralysis be monitored to avoid overdosing and metabolite accumulation, and that drug administration be curtailed periodically to allow interruption of sustained NMBD effect.