Complete reversal of neuromuscular blockade (NMB) is important for patient safety and prognosis following surgical procedures involving NMB agents (NMBAs). Published evidence on the epidemiology and consequences of residual neuromuscular blockade (rNMB; incomplete neuromuscular recovery) in real-world clinical settings is lacking with advances in NMB management. Therefore, we aimed to examine the burden of rNMB and its associated clinical, economic and humanistic outcomes using a systematic review framework.

Electronic and conference database searches were performed to include observational studies examining rNMB or related outcomes in adults undergoing surgery and receiving NMBAs with or without NMBA antagonists.

Of 1438 screened abstracts, 58 studies with 25,277 total patients were included. Inconsistent definitions of rNMB were reported across studies with 44 (76%) and 29 (50%) studies utilizing quantitative and qualitative measures to detect rNMB, respectively. The most common definition of rNMB was train-of-four ratio (TOFR) <0.9 (29 studies) and TOFR <0.7 (16 studies) measured at post-anesthesia care unit (PACU) entry. For TOFR <0.9 at PACU entry, rNMB incidence ranged from 0% to 90.5% (median 30%) overall; 0% to 16.0% in the sugammadex (SUG) group; 3.5% to 90.5% in the neostigmine (NEO) group; and 15% to 89% in the spontaneous recovery (SR) group. Twenty-one studies reported clinical outcomes (reintubation, mild hypoxemia, or a respiratory event) or resource utilization outcomes (hospital/PACU length of stay [LOS]) by presence/absence of rNMB. Patients with rNMB had higher rates of acute respiratory events compared to those without rNMB.

Real-world observational studies show a significant burden of rNMB and associated health sequelae, though rNMB measures were not reported consistently across studies. Appropriate quantitative measurement is needed to accurately identify rNMB, and interventions are needed to reduce its burden and associated adverse outcomes.