Effect of intraoperative administration of magnesium on residual neuromuscular blockade: a retrospective cohort study

Magnesium has been used as an adjuvant to general anaesthesia owing to its multiple benefits, including potentiating the action of rocuronium. However, magnesium may affect neostigmine-induced neuromuscular blockade recovery. The effects of intraoperative magnesium administration on residual neuromuscular blockade (RNMB) were investigated. This retrospective study reviewed the data of adult patients who underwent general anaesthesia with rocuronium as the neuromuscular blocking agent and neostigmine as the reversal agent, between 2018 and 2020. RNMB was defined as the administration of an additional reversal agent (neostigmine or sugammadex) in the post-anaesthesia care unit. The incidence of RNMB was compared between magnesium and control groups, and logistic regression analysis identified risk factors. Of 61,471 patients, 23,523 were included in the logistic regression analysis. After propensity score matching, 5166 patients from each group were compared, and RNMB incidence was comparable between the magnesium and control groups. In the logistic regression analysis, the risk factors for RNMB were older age (odds ratio: 1.02; 95% confidence interval: 1.01-1.03; p<0.001), male gender (1.72; 1.33-2.23; p<0.001), higher American Society of Anesthesiologists physical status (2.08; 1.54-2.82; p<0.001), limb surgery (1.46; 1.01-2.12; p=0.042), volatile anaesthetics, sevoflurane (1.84; 1.27-2.66; p=0.001), and intraoperative hypothermia (1.58; 1.13-2.23; p=0.008). Magnesium increased the risk of RNMB in patients anesthetized by propofol (2.22; 1.46-3.38; p<0.001) and sevoflurane (2.57; 1.60-4.11; p<0.001), but not desflurane (p≥0.05). Intraoperative magnesium increases the risk of RNMB in patients anesthetized with propofol and sevoflurane, and should be used with caution depending on the type of general anaesthetic agent administered.