In this review, we summarize the clinical implications of residual neuromuscular block. Data suggest that residual neuromuscular block is a common complication in the postanesthesia care unit, with approximately 40% of patients exhibiting a train-of-four ratio <0.9. Volunteer studies have demonstrated that small degrees of residual paralysis (train-of-four ratios 0.7-0.9) are associated with impaired pharyngeal function and increased risk of aspiration, weakness of upper airway muscles and airway obstruction, attenuation of the hypoxic ventilatory response (approximately 30%), and unpleasant symptoms of muscle weakness. Clinical studies have also identified adverse postoperative events associated with intraoperative neuromuscular management. Large databased investigations have identified intraoperative use of muscle relaxants and residual neuromuscular block as important risk factors in anesthetic-related morbidity and mortality. Furthermore, observational and randomized clinical trials have demonstrated that incomplete neuromuscular recovery during the early postoperative period may result in acute respiratory events (hypoxemia and airway obstruction), unpleasant symptoms of muscle weakness, longer postanesthesia care unit stays, delays in tracheal extubation, and an increased risk of postoperative pulmonary complications. These recent data suggest that residual neuromuscular block is an important patient safety issue and that neuromuscular management affects postoperative outcomes.

Background: Traditionally, reversal of nondepolarizing neuromuscular blocking agents was achieved using acetylcholinesterase inhibitors, but these are unable to adequately reverse profound blockade. Sugammadex is a novel reversal agent, reversing the effects of rocuronium by encapsulation. This study assessed the efficacy and safety of sugammadex versus neostigmine for reversal of profound rocuronium-induced neuromuscular blockade. Methods: This phase III, randomized study enrolled surgical patients, aged 18 yr or older with American Society of Anesthesiologists physical status I-IV. Patients were randomized to receive sugammadex (4.0 mg/kg) or neostigmine (70 microg/kg) plus glycopyrrolate (14 microg/kg). Anesthetized patients received an intubating dose of rocuronium (0.6 mg/kg), with maintenance doses (0.15 mg/kg) as required. Neuromuscular monitoring was performed by acceleromyography. Sugammadex or neostigmine was administered at reappearance of 1-2 posttetanic counts (profound neuromuscular blockade). The primary efficacy parameter was the time from sugammadex or neostigmine-glycopyrrolate administration to return of the train-of-four ratio to 0.9. Results: In the intent-to-treat population (n = 37 in each group), geometric mean time to recovery to a train-of-four ratio of 0.9 with sugammadex was 2.9 min versus 50.4 min with neostigmine-glycopyrrolate (P < 0.0001) (median, 2.7 min vs. 49.0 min). Most sugammadex patients (97%) recovered to a train-of-four ratio of 0.9 within 5 min after administration. In contrast, most neostigmine patients (73%) recovered between 30 and 60 min after administration, with 23% requiring more than 60 min to recover to a train-of-four ratio of 0.9. Conclusions: Recovery from profound rocuronium-induced neuromuscular blockade was significantly faster with sugammadex versus with neostigmine, suggesting that sugammadex has a unique ability to rapidly reverse profound rocuronium neuromuscular blockade.

Postoperative residual neuromuscular block is a frequent occurrence. Recent surveys of clinical practice in Europe suggest that neuromuscular blocking drugs are often administered without appropriate monitoring. No comparable survey has been undertaken in the United States (US). From this survey, we compared current clinical neuromuscular practice and attitudes between anesthesia practitioners in the US and Europe. We conducted an Internet-based survey among anesthesia practitioners in the US and Europe. The Anesthesia Patient Safety Foundation and the European Society of Anaesthesiology e-mailed all of their active members, inviting them to anonymously answer a series of questions on a dedicated Internet Protocol address-sensitive website. The survey was available online for 60 days. The chi(2) test and Fisher's exact test were used to compare clinical survey items between the 2 cohorts. A total of 2636 completed surveys were received. Most respondents from the US (64.1%) and Europe (52.2%) estimated the incidence of clinically significant postoperative residual neuromuscular weakness to be <1% (P < 0.0001). Routine pharmacologic reversal was less common in Europe than in the US (18% vs 34.2%, respectively; P < 0.0001), and quantitative monitors were available to fewer clinicians in the US (22.7%) than in Europe (70.2%) (P < 0.0001). However, 19.3% of Europeans and 9.4% of Americans never use neuromuscular monitors. Most respondents reported that neither conventional nerve stimulators nor quantitative train-of-four monitors should be part of minimum monitoring standards. Our results suggest a lack of agreement among anesthesia providers about the best way to monitor neuromuscular function. Efforts to improve awareness by developing formal training programs and/or publishing official guidelines on best practices to reduce the incidence of postoperative neuromuscular weakness and patient morbidity are warranted.

A panel of clinician scientists with expertise in neuromuscular blockade (NMB) monitoring was convened with a charge to prepare a consensus statement on indications for and proper use of such monitors. The aims of this article are to: (a) provide the rationale and scientific basis for the use of quantitative NMB monitoring; (b) offer a set of recommendations for quantitative NMB monitoring standards; (c) specify educational goals; and (d) propose training recommendations to ensure proper neuromuscular monitoring and management. The panel believes that whenever a neuromuscular blocker is administered, neuromuscular function must be monitored by observing the evoked muscular response to peripheral nerve stimulation. Ideally, this should be done at the hand muscles (not the facial muscles) with a quantitative (objective) monitor. Objective monitoring (documentation of train-of-four ratio ≥0.90) is the only method of assuring that satisfactory recovery of neuromuscular function has taken place. The panel also recommends that subjective evaluation of the responses to train-of-four stimulation (when using a peripheral nerve stimulator) or clinical tests of recovery from NMB (such as the 5-second head lift) should be abandoned in favor of objective monitoring. During an interim period for establishing these recommendations, if only a peripheral nerve stimulator is available, its use should be mandatory in any patient receiving a neuromuscular blocking drug. The panel acknowledges that publishing this statement per se will not result in its spontaneous acceptance, adherence to its recommendations, or change in routine practice. Implementation of objective monitoring will likely require professional societies and anesthesia department leadership to champion its use to change anesthesia practitioner behavior.

Postoperative residual neuromuscular block has been recognized as a potential problem for decades, and it remains so today. Traditional pharmacologic antagonists (anticholinesterases) are ineffective in reversing profound and deep levels of neuromuscular block; at the opposite end of the recovery curve close to full recovery, anticholinesterases may induce paradoxical muscle weakness. The new selective relaxant-binding agent sugammadex can reverse any depth of block from aminosteroid (but not benzylisoquinolinium) relaxants; however, the effective dose to be administered should be chosen based on objective monitoring of the depth of neuromuscular block. To guide appropriate perioperative management, neuromuscular function assessment with a peripheral nerve stimulator is mandatory. Although in many settings, subjective (visual and tactile) evaluation of muscle responses is used, such evaluation has had limited success in preventing the occurrence of residual paralysis. Clinical evaluations of return of muscle strength (head lift and grip strength) or respiratory parameters (tidal volume and vital capacity) are equally insensitive at detecting neuromuscular weakness. Objective measurement (a train-of-four ratio greater than 0.90) is the only method to determine appropriate timing of tracheal extubation and ensure normal muscle function and patient safety.