Residual Neuromuscular Block and Adverse Respiratory Events

This is the authors' abstract. We don't add key points for this paper.

In Response: Dr. Kopman's response to our investigation highlights several important issues related to residual neuromuscular blockade.1 First, we agree that many clinicians do not perceive postoperative residual paresis as a clinical problem. Recent surveys have demonstrated that many anesthesiologists do not routinely use techniques that have been proven to reduce the incidence of postoperative residual neuromuscular blockade.2,3 Second, we also agree that residual neuromuscular blockade (a train-of-four (TOF) ratio <0.9) was likely present in a number of patients without obvious respiratory symptoms. If we assume that our control group represented the study population as a whole (9.5% with TOF ratios between 0.7 and 0.9), then 708 patients would have had evidence of incomplete neuromuscular recovery in the postanesthesia care unit. Since only 61 patients had critical respiratory events, this estimation suggests that the majority (91%) of patients with residual neuromuscular blockade did not develop severe respiratory symptoms in the postanesthesia care unit. However, it is possible that more subtle respiratory events that were not measured in the study occurred in these patients with lesser degrees of muscle weakness. Furthermore, nearly three-quarters of the critical respiratory events were observed in patients with severe residual blockade (TOF ratios <0.7). Our findings suggest that the risk of critical respiratory events is more likely when more severe residual paresis is present. However, these events may still be observed in patients with less significant degrees of residual block (16.7% of the respiratory events were observed in patients with TOF ratios between 0.7 and 0.9). Finally, we agree that clinicians should not accept even infrequent adverse events if they can be prevented. We hope that our findings will make clinicians more aware of the hazards of incomplete neuromuscular recovery in the immediate postoperative period. Glenn S. Murphy, MD Joseph W. Szokol, MD Jesse H. Marymont, MD Steven B. Greenberg, MD Michael J. Avram, PhD Jeffery S. Vender, MD Department of Anesthesiology Evanston Northwestern Healthcare Evanston, Illinois [email protected]

Severe residual neuromuscular blockade (TOF <0.7) is associated with a higher risk of critical respiratory events in the postanesthesia care unit.