Study objective: To determine the incidence burden and associated risk factors of residual neuromuscular block (rNMB) during routine U.S. hospital care.
Design: Blinded multicenter cohort study.
Setting: Operating and recovery rooms of ten community and academic U.S. hospitals.
Patients: Two-hundred fifty-five adults, ASA PS 1-3, underwent elective abdominal surgery with general anesthesia and ≥1 dose of non-depolarizing neuromuscular blocking agent (NMBA) for endotracheal intubation and/or maintenance of NMB between August 2012 and April 2013.
Interventions: TOF measurements using acceleromyography were performed on patients already receiving routine anesthetic care for elective open or laparoscopic abdominal surgery. Measurements allowed assessment of the presence of residual neuromuscular block (rNMB), defined as a train-of-four (TOF) ratio <0.9 at tracheal extubation. We recorded patient and procedural characteristics and assessed TOF ratios (T4/T1) at various times throughout the procedure and at tracheal extubation. Differences in patient and clinical characteristics were compared using Fisher's exact test for categorical variables and t-test for continuous variables. Multivariate logistic regression assessed risk factors associated with rNMB at extubation.
Main results: Most of the study population, 64.7% (n = 165) had rNMB (TOF ratio < 0.9), among them, 31.0% with TOF ratio <0.6. Among those receiving neostigmine and/or qualitative peripheral nerve stimulation per clinical decision, 65.0% had rNMB. After controlling for confounders, we observed male gender (odds ratio: 2.60, P = 0.008), higher BMI (odds ratio: 1.04/unit, P = 0.043), and surgery at a community hospital (odds ratio: 3.15, P = 0.006) to be independently associated with increased odds of rNMB.
Conclusions: Assessing TOF ratios blinded to the care team, we found that the majority of patients (64.7%) in this study had rNMB at tracheal extubation, despite neostigmine administration and qualitative peripheral nerve stimulation used for routine clinical care. Qualitative neuromuscular monitoring and clinical judgement often fails to detect rNMB after neostigmine reversal with potential severe consequences to the patient. Our data suggests that clinical care could be improved by considering quantitative neuromuscular monitoring for routine care.
Keywords: Delayed emergence from anesthesia; Neostigmine; Neuromuscular block; Neuromuscular monitoring; Train-of-four monitoring.
Copyright © 2018 Elsevier Inc. All rights reserved.