Site Effect Concentrations of Remifentanil and Propofol for Intubation without Use of Neuromuscular Agent for Thyroid Surgery

Objective Thyroid surgery needs accuracy with the aim to limit major complications‐‐that is to say injury of recurrent laryngeal nerve. To help the surgeon, tracheal tube with recurrent laryngeal nerve monitoring can be used. This technique is possible when no muscle relaxant is injected. Remifentanil use with an objective of effect site concentration appears to be a solution for anesthesia for this type of surgery. Our work consists in studying the optimal concentration needed to realize the surgery without the necessity to use muscle relaxant and with the lowest side effects. Method Observation of practice in the department of Ear, Nose and Throat (ENT) surgery at Brest University Hospital. Fifty‐two patients undergoing thyroid surgery were assigned in 4 groups according to site effect remifentanil concentration: 4, 6, 7, and 8 ng/mL. Intubation was done by a tracheal tube with EMG electrodes to monitor recurrent laryngeal nerve during surgery. Noninvasive arterial blood pressure, heart rate changes, and BIS values were recorded every minute. Intubation conditions were assessed as excellent, good, or bad. Results Intubation conditions were better when remifentanil site effect concentration increased ( P =. 001). With a 4 ng/mL concentration, intubation conditions were always bad. On the other side, an 8 ng/mL concentration always gave good intubation conditions. Furthermore, with 4 ng/mL concentration of remifentanil, heart rate was significantly increased. There was no significant difference for all other data. Conclusion In our study, tracheal intubation for thyroid surgery using recurrent laryngeal nerve monitoring can be performed without a neuromuscular blocking agent with good conditions when remifentanil site effect concentration is above 8 ng/mL. At this concentration, no hemodynamic adverse effect was observed.