Journal of Clinical Anesthesia (2014) xx, xxx–xxx
Correspondence
Middle fixation of electromyographic endotracheal tube for intraoperative recurrent laryngeal nerve monitoring To the Editor: Recurrent laryngeal nerve (RLN) injury is one of the complications of thyroid surgery. Intraoperative laryngeal electromyographic (EMG) monitoring is being applied to prevent RLN injury [1,2]. A specialized EMG endotracheal tube (EMG ETT) is used for this technique. The EMG ETT (NIM® Standard EMG Reinforced Endotracheal tube; Medtronic, Minneapolis, MN, USA) is equipped with two pairs of stainless steel wire electrodes embedded in a silicone-based reinforced tube. Over 90 mm above the distal tip of the tube, there is a 30 mm length of electrode exposure for touching the vocal cords and facilitating EMG monitoring. Accurate positioning of the EMG ETT is important for optimal RLN monitoring. Tube malposition causes monitor dysfunction, which may provide incorrect information and probably increase the risk of nerve injury. For example, the EMG ETT will be displaced outwardly following patient positioning with hyperextension of head and neck [3]. Tube rotation or deviation also may result in monitor malfunction. The EMG ETT needs to touch the vocal cords bilaterally during surgery. Tube rotation and deviation may occur when the EMG ETT is affixed at the right or left mouth corner. Fig. 1 demonstrates similar situations using a manikin. It shows that both right side and left side mouth corner fixations have some rotation and cause loss of contact of the EMG ETTs with the contralateral vocal cord. We have encountered several cases in which only the right side vocal cord was in contact with the tube electrodes. In those patients, all of the tubes were affixed at the right mouth corner. After moving the tube to the middle of mouth, the problem of monitor malfunction was resolved. A review article has proposed international standards guidelines for intraoperative RLN monitoring [4]. However, no suggestions were offered for the fixation site of the EMG ETT. Here we recommend that, to avoid missing contact with one side vocal cord, the EMG ETT should be affixed between incisors, at the middle of the mouth.
0952-8180/© 2014 Elsevier Inc. All rights reserved.
Chen-Hwan Cherng MD, DMSc (Professor of Anesthesiology) Yi-Hsuan Huang MD (Resident in Anesthesia) Department of Anesthesiology Tri-Service General Hospital and National Defense Medical Center Neihu 114, Taipei, Taiwan E-mail address: [email protected]
A
B
C Fig. 1 Laryngeal view of three inserted electromyographic endotracheal tubes (EMG ETT) in a manikin. Fixation is shown at the (A) right mouth corner, (B) left mouth corner, and (C) middle. The photographs show that, while both the right and left side mouth corner fixations have some rotation and cause loss of contact of the EMG ETTs with the contralateral vocal cord, with the middle fixation there is no such rotation or loss of contact.
2
Correspondence Ming-Lang Shih MD (General Surgeon) Department of Surgery Tri-Service General Hospital and National Defense Medical Center Neihu 114, Taipei, Taiwan
http://dx.doi.org/10.1016/j.jclinane.2014.01.009
References [1] Shindo M, Chheda NN. Incidence of vocal cord paralysis with and without recurrent laryngeal nerve monitoring during thyroidectomy. Arch Otolaryngol Head Neck Surg 2007;133:481-5.
[2] Chiang FY, Lu IC, Kuo WR, Lee KW, Chang NC, Wu CW. The mechanism of recurrent laryngeal nerve injury during thyroid surgery–the application of intraoperative neuromonitoring. Surgery 2008;143:743-9. [3] Tsai CJ, Tseng KY, Wang FY, et al. Electromyographic endotracheal tube placement during thyroid surgery in neuromonitoring of recurrent laryngeal nerve. Kaohsiung J Med Sci 2011;27:96-101. [4] Randolph GW, Dralle H, Abdullah H, et al, International Intraoperative Monitoring Study Group. Electrophysiologic recurrent laryngeal nerve monitoring during thyroid and parathyroid surgery: international standards guideline statement. Laryngoscope 2011;121(Suppl 1):S1-S16.
Correspondence
Middle fixation of electromyographic endotracheal tube for intraoperative recurrent laryngeal nerve monitoring To the Editor: Recurrent laryngeal nerve (RLN) injury is one of the complications of thyroid surgery. Intraoperative laryngeal electromyographic (EMG) monitoring is being applied to prevent RLN injury [1,2]. A specialized EMG endotracheal tube (EMG ETT) is used for this technique. The EMG ETT (NIM® Standard EMG Reinforced Endotracheal tube; Medtronic, Minneapolis, MN, USA) is equipped with two pairs of stainless steel wire electrodes embedded in a silicone-based reinforced tube. Over 90 mm above the distal tip of the tube, there is a 30 mm length of electrode exposure for touching the vocal cords and facilitating EMG monitoring. Accurate positioning of the EMG ETT is important for optimal RLN monitoring. Tube malposition causes monitor dysfunction, which may provide incorrect information and probably increase the risk of nerve injury. For example, the EMG ETT will be displaced outwardly following patient positioning with hyperextension of head and neck [3]. Tube rotation or deviation also may result in monitor malfunction. The EMG ETT needs to touch the vocal cords bilaterally during surgery. Tube rotation and deviation may occur when the EMG ETT is affixed at the right or left mouth corner. Fig. 1 demonstrates similar situations using a manikin. It shows that both right side and left side mouth corner fixations have some rotation and cause loss of contact of the EMG ETTs with the contralateral vocal cord. We have encountered several cases in which only the right side vocal cord was in contact with the tube electrodes. In those patients, all of the tubes were affixed at the right mouth corner. After moving the tube to the middle of mouth, the problem of monitor malfunction was resolved. A review article has proposed international standards guidelines for intraoperative RLN monitoring [4]. However, no suggestions were offered for the fixation site of the EMG ETT. Here we recommend that, to avoid missing contact with one side vocal cord, the EMG ETT should be affixed between incisors, at the middle of the mouth.
0952-8180/© 2014 Elsevier Inc. All rights reserved.
Chen-Hwan Cherng MD, DMSc (Professor of Anesthesiology) Yi-Hsuan Huang MD (Resident in Anesthesia) Department of Anesthesiology Tri-Service General Hospital and National Defense Medical Center Neihu 114, Taipei, Taiwan E-mail address: [email protected]
A
B
C Fig. 1 Laryngeal view of three inserted electromyographic endotracheal tubes (EMG ETT) in a manikin. Fixation is shown at the (A) right mouth corner, (B) left mouth corner, and (C) middle. The photographs show that, while both the right and left side mouth corner fixations have some rotation and cause loss of contact of the EMG ETTs with the contralateral vocal cord, with the middle fixation there is no such rotation or loss of contact.
2
Correspondence Ming-Lang Shih MD (General Surgeon) Department of Surgery Tri-Service General Hospital and National Defense Medical Center Neihu 114, Taipei, Taiwan
http://dx.doi.org/10.1016/j.jclinane.2014.01.009
References [1] Shindo M, Chheda NN. Incidence of vocal cord paralysis with and without recurrent laryngeal nerve monitoring during thyroidectomy. Arch Otolaryngol Head Neck Surg 2007;133:481-5.
[2] Chiang FY, Lu IC, Kuo WR, Lee KW, Chang NC, Wu CW. The mechanism of recurrent laryngeal nerve injury during thyroid surgery–the application of intraoperative neuromonitoring. Surgery 2008;143:743-9. [3] Tsai CJ, Tseng KY, Wang FY, et al. Electromyographic endotracheal tube placement during thyroid surgery in neuromonitoring of recurrent laryngeal nerve. Kaohsiung J Med Sci 2011;27:96-101. [4] Randolph GW, Dralle H, Abdullah H, et al, International Intraoperative Monitoring Study Group. Electrophysiologic recurrent laryngeal nerve monitoring during thyroid and parathyroid surgery: international standards guideline statement. Laryngoscope 2011;121(Suppl 1):S1-S16.
