Duration of neuromuscular blockade following standard induction dose of rocuronium in parotid surgery: a retrospective observational study

BACKGROUND: Due to the effects of NMBA administered during induction, intraoperative nerve monitoring may not respond properly during parotid gland surgery. OBJECTIVE: To investigate the relationship between NMBA administration during anesthesia induction and the time to recovery for intraoperative nerve monitoring in parotid gland surgery. MATERIALS AND METHODS: We retrospectively reviewed the medical records of 190 patients who underwent surgery for benign parotid tumors. We examined the factors associated with prolonged neuromuscular blockade. The correlation between NMBA dose per body weight and time to TOFC = 4 was also examined. RESULTS: The incidence of TOFC = 4 was 5.3% at 20 min, 33.2% at 40 min, 73.1% at 60 min, 91.6% at 80 min, and 96.3% at 100 min after NMBA administration. The time to TOFC = 4 was prolonged with a higher rocuronium dose per body weight, older age, and reduced renal function, each being an independent factor. A positive correlation was observed between NMBA dose and time to TOFC = 4. The administering rocuronium at 0.6 mg/kg during induction resulted in a TOFC = 4 time of 51.5 min. CONCLUSION: In parotid gland surgery, the effects of NMBAs used during induction may persist in some cases.