Adverse event using Medtronic NIM(™) EMG endotracheal tube on a patient receiving anesthesia for hemithyroidectomy: a case report

BACKGROUND: The neural integrity monitor (NIM) electromyogram (EMG) endotracheal (ET) tube is a widely used device to monitor neural response through muscle activity. It is helpful in surgical procedures with high risk of damaging delicate structures in the head and neck. This case provides a thorough analysis of an adverse event that was encountered in the operating room, which others can hopefully learn from. CASE PRESENTATION: We are reporting a case in which a patient undergoing hemithyroidectomy had experienced an adverse event using the Medtronic NIM(™) EMG endotracheal tube. After successful induction and intubation, confirming the proper positioning of the electrode wires was necessary before the incision could be made. Upon reexamination, the patient suddenly became difficult to ventilate with increased peak airway pressure, decreased tidal volume, and end tidal CO2. This episode lasted approximately 15 min and the patient’s condition remained stable despite low tidal volumes. The problem was unexpectedly resolved upon deflation of the cuff of the ET tube. CONCLUSIONS: There are several similar reports of these endotracheal tubes causing obstruction, especially those in which overinflation of the cuff caused cuff herniation and blockage of the Murphy eye and the bevel. It is currently believed that the design of this tube allowed for the obstruction to occur. The patient’s short body habitus may have also been a small contributing factor. The distance that the electrodes must sit within the vocal cords to the tip of the bevel is longer in this type of ET tube compared with a standard ET tube. The distance from the true vocal cords to where the cuff sits in the trachea is also greater in this model NIM EMG tube. There was no confirmation of the exact obstructive process that took place, however, confirming the tube and cuff positioning would have been optimal.