Is Postoperative Residual Neuromuscular Block Associated with Adverse Clinical Outcomes? What Is the Evidence?

Abstract

Satisfactory recovery from nondepolarizing neuromuscular block is currently defined as return of the train-of-four ratio at the adductor pollicis muscle to a value of 0.90 or greater. Studies in volunteers demonstrate that train-of-four ratios of 0.70–0.80 are associated not only with subjective symptoms of weakness, but also dysfunction of the muscles of airway patency and swallowing. There is ample evidence that a sizeable proportion of patients who receive nondepolarizing neuromuscular blocking agents return to postanesthesia care units with undetected postoperative residual neuromuscular block (postoperative muscle weakness). However, until recently, outcome studies that demonstrate that postoperative weakness may be associated with adverse patient outcomes have been lacking. This review is an attempt to collate the available data that suggest that even modest levels of residual block have untoward clinical consequences.