Article ID: JNMS.2019_86-408
Background: Intraoperative neuromonitoring (IONM) could reduce the incidence of injury to the recurrent laryngeal nerve (RLN) during thyroidectomy. Although the dislocation of endotracheal tube surface electrodes can lead to false positive IONM results (loss of signals), the risk factors remain unclear, as does the influence of muscle relaxants. Therefore, to identify factors that can affect IONM results, we examined the frequency and risk factors of tube dislocation after cervical extension prior to surgery, the effect of sugammadex administration, and the correlation between IONM results and postoperative RLN palsy.
Methods: Thirty-nine patients scheduled for thyroidectomy from October 2016 to April 2017 were enrolled. All patients underwent standard IONM and pre- and postoperative laryngoscopy. Differences in patient characteristics between the tube dislocation group and the non-dislocation group, and differences in the amplitude at vagal stimulation between before and after sugammadex administration, were assessed by the Mann–Whitney test or Fisher's exact test.
Results: Tube dislocation was observed in 27 patients (69%). The dislocation group (n=27) had a significantly shorter sterno-cricoid distance than the non-dislocation group (n=12) (43.88 (32.2–55.91) mm vs 49.46 (40.66–55.91) mm, respectively ;p=0.048). Without sugammadex, the amplitude at vagal stimulation was enough for monitoring. Nine patients had new-onset RLN palsy, but all of them were transient. The sensitivity of IONM was 100%, the predictive positive value was 60%, and the negative predictive value was 100%.
Conclusions: This study suggested that anesthesiologists should correct tube dislocation reliably with video laryngoscope. The dose of rocuronium 0.6 mg/kg without sugammadex could be adequate for IONM.
