NerveTrend vs. NerveAssure in Prevention of Recurrent Laryngeal Nerve Injury During Thyroid Surgery

The NIM Vital system (Medtronic, Jacksonville, US) operates with surface electrodes integrated with an endotracheal NIM TriVantage tube 7.0-8.0 in diameter, which is inserted by an anesthetist between the vocal folds under direct vision during intubation. The standardized technique of IONM RLNs wll be used, including initial vagal response evaluation at the beginning and final vagal response evaluation at the end of surgery (IONM = L1+V1+R1+R2+V2+L2) according to the recommendations formulated by the International Intraoperative Neural Monitoring Study Group. The nerves will be stimulated using a monopolar electrode and the interrupted stimulation technique at 1mA, 100ms impulse duration and 4Hz frequency. In case of the bifurcated RLN nerves, the assessment includes post-stimulation response of each nerve branch. Adduction of the vocal folds is detected by the endotracheal tube electromyography and abduction by finger palpation of muscle contraction in the posterior cricoarytenoid.