"To Reverse or Not To Reverse?": The Answer Is Clear!

<zdoi;10.1097/ALN.0000000000001280> Anesthesiology, V 125 • No 4 611 October 2016 B y the late 1980s, it was well recognized that undetected postoperative residual neuromuscular block (PRNB) was a common occurrence in most postanesthesia care units (PACUs). 1–4 However, an editorial in 1989 noted that there was little, if any, objective evidence to validate the hypothesis that PRNB was associated with long-term or even transient adverse respiratory outcomes.5 In the two and a half decades since the editorial by Miller5 was published, outcome data regarding this important patient safety issue have slowly accumulated, but the relevant database remains quite sparse. In this issue of ANestHesIology, Bulka et al.6 provide an important addition to the small list of studies that attempt to examine the long-term consequences of PRNB. They report two main findings: (1) the use of neuromuscular blocking agents (NMBAs) was associated with a higher absolute rate of postoperative pneumonia (PoP) when compared to matched cases where patients did not receive relaxants and (2) failure to reverse NMBAs at the end of surgery was associated with a 2.25-fold increase in the incidence of PoP. Why should these findings be less than surprising? Bulka et al.6 noted that the incidence rate ratio (1.79) for PoP was significantly higher in patients who received NMBAs. This observation is consistent with the findings from several large database investigations, which have described an association between intraoperative NMBA use and major morbidity and mortality. More than 60 yr ago, Beecher and todd7 reported that the risk of death related to anesthesia was six times higher in patients receiving NMBAs compared to those administered no muscle relaxants. An analysis of data collected over a 10-yr period (1967 to 1976) involving 240,483 anesthetics revealed that “respiratory inadequacy after myoneural blockade” was the second most common cause of death after surgery.8 similarly, a study from great Britain reported that postoperative respiratory failure secondary to dosing of NMBAs was a primary cause of mortality.9 In a large prospective study, the use of the long-acting NMBA pancuronium entailed a higher risk of postoperative pulmonary complications.10 More recent studies reported that patients administered NMBAs had a higher risk of postoperative desaturations and need for reintubation11 and that those given high doses of NMBAs had an increased risk of postoperative respiratory complications.12 The increased incidence of morbidity and mortality reported in patients administered NMBAs is likely secondary to PRNB. Incomplete neuromuscular recovery during a vulnerable postoperative period (between tracheal extubation and achieving a train-of-four [toF] ratio of less than 0.9 in the PACU) may impair upper airway patency, protective airway reflexes, breathing, swallowing, and coughing, resulting in an increased risk of significant respiratory events (like PoP) and death. Data demonstrating an association between failure to reverse neuromuscular blockade and adverse postoperative outcomes are less certain. A large case–control database investigation revealed that the primary anesthetic management characteristic associated with a reduction in mortality and coma was reversal of the effects of NMBAs.13 In a “To Reverse or Not To Reverse? ”