Intraoperative anaphylaxis to neuromuscular blocking agents

Background Intraoperative anaphylaxis to neuromuscular blocking agents (NMBAs) is a rare event that is unpredictable and potentially life threatening. Most of the previous reports on such intraoperative anaphylaxis used market share surveys or self-reported data to estimate the incidence. Objective To determine the incidences of intraoperative anaphylaxis to NMBAs using electronic medical records. Design A retrospective observational study. Setting Two tertiary hospitals in South Korea. Patients This study involved patients exposed to NMBAs during anaesthesia between 1 January 2005 and 31 May 2014. Nineteen episodes were deemed to be intraoperative anaphylaxis to NMBAs. Main outcome measures We calculated the incidences of intraoperative anaphylaxis to NMBAs. Exposure to the agents was determined from intraoperative records maintained in an electronic medical recording system. An anaphylactic reaction was determined from both clinical signs and the results of skin tests. Results Over 9 years, 729 429 patients were exposed to NMBA, the most frequently used being rocuronium [425 047 (58.3%)] and vecuronium [274 801 (37.7%)]. The overall incidence of intraoperative anaphylaxis was 2.6 per 100 000 (19 cases), and was higher with rocuronium (16 cases, 3.8 per 100 000) than with vecuronium (two cases, 0.7 cases per 100 000), P = 0.014. Comparing the first 3 years with the last 6 years, the incidence of intraoperative rocuronium anaphylaxis appeared to increase 1.4-fold (P = 0.006). Conclusion Among commonly used NMBAs, rocuronium appears to have the highest incidence of anaphylaxis. Our findings suggest that future prospective investigation for NMBA-induced anaphylaxis should use internationally agreed skin test protocols.