Neuromuscular Management and Patient Outcomes

Abstract

Learning Objectives:As a result of completing this activity, the participant will be able to Discuss neuromuscular monitoring and its impact on postoperative outcomes Describe the effect of reversal of neuromuscular blocking agents on the incidence of postoperative residual neuromuscular blockade Explain principles of neuromuscular management that may beneficially impact postoperative recovery in surgical patients Author Disclosure Information:Dr. Murphy has disclosed that he receives consulting fees and honoraria from Merck. P ostoperative residual neuromuscular blockade after general anesthesia is a common complication observed in the postanesthesia care unit (PACU). Recent large-scale clinical investigations have demonstrated that up to 24 to 42% of surgical patients arrive in the PACU with evidence of incomplete neuromuscular recovery. 1,2 Although most clinicians are now using intermediate-acting muscle relaxants, the risk of a residual neuromuscular block does not appear to be decreasing over time. In a metaanalysis of data from 24 clinical trials, the pooled rate of residual block, defined as a train-of-four (TOF) ratio less than 0.9, was 41% when studies using intermediate-acting neuromuscular blocking agents (NMBAs) were analyzed 3 (Table 1).To reliably detect and treat residual neuromuscular block, quantitative neuromuscular monitors (which measure and quantify muscle strength on a 0 to 100% or 0 to 1.0 scale) are required. A large number of laboratory and clinical investigations have demonstrated that TOF ratios, measured with a quantitative neuromuscular monitor, must recover to at least 0.9 (or 90%) to exclude clinically significant residual block. Investigations with awake volunteers have demonstrated that subjects with a TOF ratio less than 0.9 have upper airway obstruction, reduced upper airway tone and diameter, pharyngeal dysfunction, impaired hypoxic ventilatory control, decreased upper esophageal tone and an increased risk for aspiration, and unpleasant symptoms of muscle weakness. 4 Epidemiological outcome investigations have suggested an association between incomplete neuromuscular recovery and major morbidity (primarily respiratory events) and mortality. 4,5 Clinical trials have demonstrated that patients with a TOF ratio less than 0.9 in the PACU are at increased risk for airway obstruction, hypoxemic events, postoperative pulmonary complications, unpleasant symptoms of muscle weakness, and prolonged PACU admission times. 4 Careful management of neuromuscular blockade in the perioperative period may decrease the incidence of 80