: 2022  |  Volume : 5  |  Issue : 1  |  Page : 54--56

Electromyography endotracheal tube – Road to safety for thyroid surgery

Tina Khurana, Rejitha Chandrasekharan, Mohandeep Kaur, Shruti Sharma 
 Department of Anaesthesiology and Critical Care, ABVIMS & Dr RML Hospital, New Delhi, India

Correspondence Address:
Dr. Rejitha Chandrasekharan
Amrita Institute of Medical Sciences, Kochi, Kerala


Thyroidectomy is one among the most commonly performed endocrine surgeries. Iatrogenic injury of the recurrent laryngeal nerve (RLN) is of major concern in thyroid surgery. We report the case of a 37-year-old female with papillary carcinoma of thyroid posted for total thyroidectomy. Although direct identification of the nerve is considered as the gold standard, we discuss the intraoperative monitoring of RLN using electromyography endotracheal tube and its anaesthetic considerations.

How to cite this article:
Khurana T, Chandrasekharan R, Kaur M, Sharma S. Electromyography endotracheal tube – Road to safety for thyroid surgery.Airway 2022;5:54-56

How to cite this URL:
Khurana T, Chandrasekharan R, Kaur M, Sharma S. Electromyography endotracheal tube – Road to safety for thyroid surgery. Airway [serial online] 2022 [cited 2023 Feb 1 ];5:54-56
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Full Text


Thyroidectomy is one among the most commonly performed endocrine surgeries. Recurrent laryngeal nerve (RLN) injury during thyroid surgery has an incidence of 1.5%–14%.[1] It is a debilitating complication affecting quality of life. RLN injury is an avoidable complication of thyroid surgery. Monitoring for this complication is quite essential for patient safety and it deserves serious consideration. Surgical technique and expertise are no doubt crucial factors. Methods which can decrease it are of great clinical significance. Although direct identification of the nerve is considered as the gold standard, we discuss the role of electromyography (EMG) endotracheal tube in tracing the course of the RLN intraoperatively and thus preventing complications. Informed written consent was obtained from the patient for the use of this modality.

 Case Report

A 37-year-old female patient with papillary carcinoma of thyroid was posted for total thyroidectomy. She had complaints of swelling over the neck for the past 2 years with no history suggestive of compression or obstruction. The patient was euthyroid and preoperative blood investigations were normal. Chest X-ray showed mild deviation of trachea to the left. Indirect laryngoscopy showed bilateral mobile vocal cords. The patient was premedicated with intravenous glycopyrrolate 0.2 mg and infusion of dexmedetomidine 1 μg/kg over a period of 10 min under neuromuscular transducer (NMT) and bispectral index (BIS) monitoring along with standard monitoring that included electrocardiogram, noninvasive blood pressure and pulse oximetry. The patient was preoxygenated with 100% oxygen for 3 min and was induced with fentanyl 2 μg/kg, propofol 2 mg/kg and succinylcholine 2 mg/kg. The airway was secured with a 7.0 mm ID cuffed NIM™ TriVantage™ EMG tube confirming the placement of electrodes at the level of vocal cords. Anaesthesia was maintained using 50% oxygen in air, sevoflurane of 1 MAC and dexmedetomidine infused at 0.5–0.7 μg/kg/h to maintain BIS values between 40 and 60. With the use of neuromuscular monitoring (NMT), complete recovery from succinylcholine was confirmed. Thereafter, no neuromuscular blocking agent was used. Throughout the surgery, the train-of-four count was kept at 4. The integrity of the intraoperative nerve monitoring was confirmed by the surgeon by directly stimulating the nerve with 0.5 to 1 mA which gave a sinusoidal waveform pattern on the nerve integrity monitor. The patient was haemodynamically stable throughout the surgery. Nerve intactness was reconfirmed again before closure by stimulating the nerve. The infusions were stopped after removal of the gland. The patient was extubated under videolaryngoscopy to confirm the movement of vocal cords. Postoperatively, vocalisation was normal.


RLN injury is an infrequent but devastating complication of thyroid surgeries. It can manifest as dysphagia, dysphonia, airway obstruction and aspiration. It may occur due to direct injury to the nerve, transection, postoperative haematoma or oedema.[2] It is well known that visual identification as shown in [Figure 1] is the classic gold standard method for avoiding RLN injury, but in recent times, various other intraoperative nerve monitoring methods have gained widespread acceptance as a further aid to visual identification of the nerve.[3],[4] The EMG tube is a novel silicon-based reinforced endotracheal tube which can be used during thyroid, parathyroid and head-and-neck surgeries for monitoring and preventing iatrogenic nerve injuries and their attendant complications. It has a minimum outer diameter of 8.0 mm and hence can be inserted only orally. The NIM™ TriVantage™ EMG tube is a single use, non-reinforced polyvinylchloride tube free of diethyl-hexaphthalate. The advantage of this tube is that it has a smaller outer diameter, is longer, flexible with reduced sensitivity to movement and rotation and an increased electromyographic responsiveness as compared to the older endotracheal tubes. It has smooth conductive silver ink electrodes which are to be positioned at the level of vocal cords. A cross band is present to aid in the placement. Vocalis muscle activity is to be recorded on RLN stimulation.[5] EMG endotracheal tube herniation has been reported on reuse and while using nitrous oxide anaesthesia.[6] The cuff should be lubricated with an aqueous gel before placement. Due to the associated potential for electric fire hazard, a lower FIO2 is to be preferred. The role of the anaesthesiologist is to guarantee the best signal during intraoperative nerve monitoring. The ultimate challenge for the anaesthesiologist would be to position the endotracheal tube in close proximity to the vocal cords while avoiding any inappropriate use of anaesthetic drugs that can alter the signal. The anaesthesiologist should also ensure proper placement of the electrodes in proximity to vocal cords after neck extension as this is the key for successful intraoperative nerve monitoring. There can be significant displacement of electrodes following neck extension, but this fact is seldom discussed in the literature. Neuromuscular blocking agents (NMBAs) reduce the amplitude of the signal thereby impeding the monitoring, making it less sensitive for detecting nerve injury. Hence, NMBAs should be avoided altogether during the procedure as a functioning neuromuscular junction is essential for effective monitoring. Since NMBAs are not to be used, a deeper plane of anaesthesia is required during the surgery to ensure complete avoidance of spontaneous movement of vocal cords.{Figure 1}


EMG endotracheal tube is a useful addition to the armamentarium of the anaesthesiologist that helps in reducing iatrogenic RLN injury with more expedient identification of the nerve. Such monitoring allows the surgeon to document that the nerve was preserved with a timed nerve signal which could be of use in the medicolegal context. We believe that routine clinical application and cost-effective implementation of this technique will go a long way in minimising RLN injury in a select group of patients undergoing thyroid surgery and complicated head-and-neck surgery for cancer.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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