This video explains how electromyography endotracheal tubes work during thyroid surgery. Also known as, EMG ET tubes, these are a type of Intraoperative Neuromonitoring (IONM) which serve a big role preventing nerve injury by monitoring recurrent laryngeal nerve activity. Placement of the tube during intubation is important as the surface electrodes should be in contact with the vocal cords. Incorrect placement would render the tube ineffective and could cause damage to the nerve. Both, macintosh and video laryngoscopes can be used if there is poor visibility during intubation.
During surgery the tube may shift from its correct position for several reasons, primarily movement of the neck, so it’s important to check its correct placement throughout the duration of surgery. The tube itself has electrodes located at the tip. These electrodes come into contact with the vocal cords and detect electrical signals produced by the nerves. These signals are transmitted to a monitoring system which allows for continuous monitoring throughout the surgery. Once the EMG ET tube is properly placed, it can detect electrical signals produced by the nerve by using a stimulation probe. Whenever the nerve is stimulated surgeons and anesthesiologists can view the signals on a screen and listen to the sounds produced by pressing directly above the vocal cords.
The EMG signals are transmitted to a real-time monitoring system which helps surgeons view the signals on a screen and evaluate nerve integrity. During surgery this feedback helps surgeons adjust their technique to avoid nerve damage. Stimulation of the nerve creates a sinusoidal wave on the nerve integrity monitor along with an audible signal confirming its intactness. These waveforms, also known as electromyograms. In a normal resting state, should show very little electrical activity. The intensity can be seen by the amplitude of the wave. And the duration can provide information about the speed of muscle activation. A decrease or loss of EMG signals in response to nerve stimulation can indicate nerve damage or irritation.
Electromyography Endotracheal Tube use in Thyroid Surgery
EMG Endotracheal tubes are used in head and neck surgery to help monitor the activity of nerves and avoid damaging them.
Contraindications for using EMG ET tubes include tracheal stenosis, allergy or sensitivity to the materials, airway trauma or lesions, general expertise, among others.
Standard setup for intubation is needed for EMG ET tube placement. A mac blade or video laryngoscope can be used depending on visibility.
Preoperatively the patient should be evaluated to rule out any tracheal stenosis or contraindications to its use.
It’s important to preserve the function of the RLNs (recurrent laryngeal nerves) and other nerves that play a crucial role in vocal cord movement, swallowing and sensation of the neck and throat.
An advantage of using EMG ET tubes is that it helps surgeons monitor nerve activity throughout the entirety of surgery. As well as, helps avoid nerve damage. Some disadvantages would be that its displacement during surgery could lead to false readings and nerve damage.
The use of EMG ET tubes can cause airway related complications. Incorrect placement of the EMG ET tube can lead to false readings and nerve damage. Tube removal complications have also been documented due to tissue swelling around the tube.
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Dixit H, Kamat L, Potdar M, Modi T. Role of electromyography endotracheal tube in preventing recurrent laryngeal nerve injury during thyroid surgery: A case reportAirway trauma during difficult intubation… from the frying pan into the fire? Indian J Anaesth. 2017 May;61(5):435-437. doi: 10.4103/ija.IJA_414_16. PMID: 28584356; PMCID: PMC5444225.
Barber, S.R., Liddy, W., Kyriazidis, N., Cinquepalmi, M., Lin, B.M., Modi, R., Patricio, S., Kamani, D., Belotti, C., Mahamad, S., Lawson, B. and Randolph, G.W. (2017), Changes in electromyographic amplitudes but not latencies occur with endotracheal tube malpositioning during intraoperative monitoring for thyroid surgery: Implications for guidelines. The Laryngoscope, 127: 2182-2188. https://doi.org/10.1002/lary.26392
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The following video demonstrates the author’s method for repairing wide unilateral complete cleft lip and cleft nasal deformities. Details of surgical markings as well as nuances of technique are demonstrated. Video documentation of immediate results as well as progress of healing over the following year are included.
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