Cell Biochem Biophys (2015) 71:1029–1033 DOI 10.1007/s12013-014-0305-x
ORIGINAL PAPER
Complications and Adverse Effects Associated with Intraoperative Nerve Monitoring During Thyroid Surgery Under General Anesthesia Peng Chen • Feng Liang • Long-yun Li Guo-qing Zhao
•
Published online: 25 October 2014 Ó Springer Science+Business Media New York 2014
Abstract This study covers a large cohort of patients (3,029 cases) who underwent thyroid surgery under intraoperative nerve monitoring (IONM). Most common problems and complications associated with the surgery were identified and analyzed. On the basis of this analysis, we provide some practical advices and suggestions which specialists in the field will find useful in their surgical practice. The data will help in developing clear surgical guidelines for thyroid surgery with IONM and for postoperative follow-up and monitoring. Keywords Thyroid surgery Intraoperative nerve monitoring Anesthesia
Introduction Intraoperative nerve monitoring (IONM) in the course of surgical operations has been developed in recent years [1]. Among other applications, the technique is widely used for monitoring and protecting the recurrent laryngeal nerve (RLN) during the thyroid surgery, thus reducing the probability of RLN injury [2–6]. Despite general recognition of the benefits of IONM, the advantages of this approach for thyroid surgery are still debatable. A number of studies and systematic reviews point to statistically marginal advantages of IONM in
P. Chen F. Liang L. Li (&) G. Zhao (&) Department of Anesthesiology, China-Japan Union Hospital of Jilin University, No. 126 Xiantai Street, Changchun 130033, China e-mail: [email protected] G. Zhao e-mail: [email protected]
comparison with visualization alone [7–10]. These conclusions might be related to the fact that practical implementation of IONM technique is associated with a number of problems. Despite the lack of convincing evidences of the IONM’s advantages during thyroid surgery at present time, there are no doubts that this technique, once perfected, will be beneficial for patients. One of the problems the IONM is facing is the potential interferences caused by drugs used for initiating and maintaining anesthesia [11, 12]. The anesthesia during surgery is a major disturbance factor for monitoring process. In this article, we review the use of anesthesia in thyroidectomy in 3,029 surgeries performed in September 2011–November 2013. The study aims to assess the complications related to anesthesia before and after thyroid surgery and evaluate the potential standardization of anesthesia technique under IONM in thyroid surgery. The findings might contribute to the existing efforts [13–15] in developing the clear surgical guidelines for thyroid surgery under IONM monitoring.
Materials and Methods A total of 3,029 patients (461 males and 2,568 females) were submitted to thyroid surgery to China–Japan Union Hospital from September 2011 to November 2013 under general anesthesia. Patient’s age ranged from 19 to 71 and weight ranged from 37 to 109 kg. Out of the total, 2,313 patients underwent the thyroid cancer surgery. The secondary surgery was performed in 738 cases and the third surgery in 189 cases. Concurrent preoperative injuries of RLN were encountered in 213 cases, and 11 cases developed the injury in the other nerves which were classified as ASA II–III.
123
1030
Cell Biochem Biophys (2015) 71:1029–1033
Fig. 1 The special mat for thyroid surgery positioned under the patient’s neck
Anesthesia and Surgery Patients were injected with 1 mg Penehyclidine Hydrochloride 30 min before surgery. Intraoperative monitoring included noninvasive blood pressure (NIBP) monitoring, electrocardiography (ECG), oxygen saturation (SpO2), end-tidal carbon dioxide partial pressure (PetCO2 oximetry), and capnography. Patients were positioned for thyroid surgery (Fig. 1) and administered with intravenous Midazolam propofol at 2 lg/kg, sufentanil (0.5 lg/kg) and rocuronium bromide (0.3 lg/kg) (Lot H20040423, Organon Inc., The Netherlands) (Fig. 1). Tracheal catheters were inserted (Medtronic Xomed Corporation, United States). Conventional laryngoscopy with fiberoptic bronchoscopy was performed in 576 cases, and for all other patients the video laryngoscope was used. Cooper scoring was assessed, and blood pressure and pulse changes were recorded in order to evaluate the tracheal intubation conditions. Maintenance of anesthesia was achieved by sevoflurane–oxygen inhalation (50 % NO, 50 % O2), and the depth of anesthesia was kept at 1.2–1.4 MAC by adjusting sevoflurane. NIM-Response 2.0 or NIM-Response 3.0 electrical instruments (Medtronic Xomed, USA) were used for neuromuscular monitoring. After surgery, we gradually modulated the anesthesia into a lower level and maintained its depth at around 0.1 MAC manually. Then, we tried to wake up patients and wait until the breathing was restored. Patients were sent back to the surgery recovery room after the conditions were stable. At 24 h post-operatively, overall patient outcome after the treatment with IONM was recorded.
Results The endotracheal tube was successfully inserted in all patients, and all the intubation conditions were met with minimal adverse effects encountered. The vagus nerve and
123
Table 1 The complication encountered before and after surgery Pre-surgery
Number of cases
Bucking
227
Deep tracheal catheter placement
129
Tracheal catheter rotation
38
Over-secretion and unstable signal
19
Unstable blood flow dynamics
147
Oral mucosa injury
1
Post-surgery
Number of cases
Throat pain
176
Pharyngeal discomfort
234
Voice hoarse and joint half-dislocation
19
Inhaled pneumonia
3
Dry eye syndrome
21
Ear and neck numbness
21
Conjunctival congestion
49
the RLN signal (signal V/R) amplitude met all monitoring requirements and all patients underwent surgery successfully. Preoperative and post-operative problems encountered during the treatment of all patients in this study were analyzed, allocated into different categories and summarized in Table 1.
Discussion In recent years, with the rising incidence of thyroid disease, RLN injury became a very common complication during the thyroid surgery, and various practical aspects of this problem are receiving a significant attention of both medical researchers and practitioners [16–21]. IONM has been used successfully as a new revolutionary technology for identification of the RLN in thyroid surgery [22, 23]. Despite the advantages, the value of IONM still remains
Cell Biochem Biophys (2015) 71:1029–1033
Fig. 2 Comparison of the recurrent laryngeal nerve electromyographic signals generated under different anesthesia induction methods
debatable among endocrine surgeons. In this article, we aimed to present the current knowledge on the subject and summarize our experience for the anesthesia during IONM in thyroidectomy, as well as discuss the approaches to standardization of anesthesia under IONM in this surgical procedure. The induction phase is the key step of the anesthesia when thyroid surgery with IONM is performed. Unfortunately, the endotracheal intubation is very difficult to perform when non-depolarizing muscle relaxants are used. Since muscle relaxants, even in residual quantities, can interfere with nerve monitoring process [24, 25] and trigger the generation of false-positive RLN signal, thyroid surgeons tend to avoid the use of these agents. Common approach to this problem is to use depolarizing relaxant induction or no muscle relaxant induction. In China, however, due to large number of cases and shortage of specialized anesthesiologists, the inherent weakness of using depolarizing relaxant induction and the operational difficulty without muscle relaxant induction make this approach not widely accepted among specialists. In our previous study [25], we recommended to induce anesthesia by double doses of ED95 rocuronium bromide and slightly increased the dosage of the general anesthetics and analgesics. We compared the amplitudes of neuromuscular monitoring between the high doses of ED95 rocuronium bromide and sevoflurane inhalation. The former drug was found to fully satisfy all the requirements for the surgery [26] (Fig. 2). For the endotracheal tube placement under IONM, we recommended to set the patient position first (as shown on Fig. 1) and then perform tracheal intubation. In the traditional approach, the patient is adjusted to the thyroid gland position after intubation is done. This may result in the misplacement of tracheal intubation and the inaccurate measurement of the signal. Furthermore, the use
1031
of video laryngoscope is highly recommended during intubation. If video laryngoscope is not used, the intubation line needs to be marked first. The longitudinal mark line should be kept in the center position, and the horizontal mark line should be intersected with the vocal for the best positioning of the fiberoptic bronchoscope (Fig. 3). If the airway resistance increases during the intubation process, it might be caused by anesthesia being too shallow. Deep anesthesia was suggested for the induction phase. The recommended dosage for induction includes 2 lg/kg of midazolam propofol, followed by 0.5 lg/kg of sufentanil and 0.3 lg/kg of rocuronium bromide [25]. In addition, due to the relatively simple trachea cannula type produced by Medtronic Xomed Company, the available models might not match the endotracheal tube. The cuff pressure should not be too high in order to protect the tracheal mucosa. During the maintenance phase of anesthesia, it is recommended to avoid the use of the muscle relaxant under IONM in thyroid surgery due to extremely low requirements for the muscle relaxation [25]. Sevoflurane was used to maintain breath depth at around 1.2–1.6 MAC if the endtidal gas monitoring equipment was available. This depth of anesthesia should not only meet the standard requirements but also produce some central muscle relaxation effects without any signal side effect [26]. If there is no end-tidal gas monitoring equipment, anesthesiologist can use the intravenous general anesthesia or combined intravenous anesthesia. The principles are to keep the depth of anesthesia not too shallow and maintain it as smooth as possible. During the maintenance phase of anesthesia, it is also important to not attenuate the depth of anesthesia as early as possible. Intraoperative hemodynamic instability in surgery is directly related to the unstable depth of anesthesia. The direct inhibition effect of intravenous anesthesia drug on myocardium and the long fasting time can cause insufficient cycle capacity and decrease of blood pressure. Some anesthesia specialists prefer to use shallow anesthesia method to obtain relatively good blood flow dynamics indicators and do not use muscle relaxants during the maintenance phase. It is possible to have deep anesthesia and then reduce anesthesia fast, which may lead to unstable blood flow dynamics. We recommended to use end-breathing gas monitoring or BIS monitoring in order to keep the anesthesia depth stable, under the management of experienced anesthesiologist. After surgery, the patients should regain consciousness naturally in order to reduce the anesthesia complications such as restlessness. We learned that we should keep the anesthesia stable before the end of surgery, and then gradually reduce the depth of anesthesia once surgery is finished. In general, the depth of anesthesia can be reduced to about 0.1 MAC after 10 min. When the depth of anesthesia is around 0.2–0.3 MAC, the patient should not be
123
1032
Cell Biochem Biophys (2015) 71:1029–1033
Fig. 3 The use of video laryngoscope for tracheal intubation
stimulated, otherwise restlessness can be caused very easily. When anesthetic depth is dropped below 0.1 MAC, we can control breathing manually, restore the breathing, wake up patients, and then perform the tracheal extubation and encourage the patient to cough. If there is any cough or breath before the anesthetic depth was dropped below 0.1 MAC, we can directly control breathing manually, but should not irritate the patient in order to prevent iatrogenic throat pain and discomfort. Sometimes the neuromuscular monitoring signal weakens or disappears during the surgery. Except for operative reasons, the common causes include the overdose of non-depolarizing muscle relaxants, endotracheal tube misplacement (too deep, too shallow, or rotated), loop electrode going off, machine malfunctions, and a number of other less common problems. The first three are the most common reasons for the weakening or disappearing of signal. The causes of unstable signal can be related to the airway over-secretion if the patients had been in shallow anesthesia state for a long time. Also, the use of non-anti-choline class drugs before the surgery or long surgery time can lead to the airway over-secretion and cause the signal instability. Furthermore, inappropriate use of electric knife and detection electrode can interfere with the signal from other muscle groups and increase the instability of signal. The use of video laryngoscope requires proper training of the practitioners. Improper use of video laryngoscopes can lead to the post-operative hoarseness and half-dislocation of cricoarytenoid joint. Video laryngoscope is different from usual laryngoscope since the latter has 0° lens.
123
In our cohort, one of the patients suffered lateral pharyngeal wall mucosal injury and bleeding due to the improper use of video laryngoscopes. In addition, the small number of available endotracheal tube models produced by Medtronic Xomed that are used for RLN monitoring might cause additional problems. Our experience suggests that we should encourage patients to cough immediately after extubation. In addition, post-surgery branchofiberoscope examination is important and can help to identify the problem of arytenoid subluxation. Conjunctival hyperemia and dry eye syndrome sometimes happened as a result of surgery. They might have been caused by the long operation time and improper sterile bedding which leads to poor eyelid closure. In the study group, there were 21 patients with post-surgery dry eye syndrome, of which 17 were ‘‘double eyelid’’ surgery patients. The use of eye-patch or eye ointment is therefore recommended. The facial numbness is caused by overstretching of the head. Reducing the operating time as much as possible and explaining clearly to the patients before operation that facial numbness may appear after the surgery are very important for reducing the risk of this complication and avoiding the patient’s dissatisfaction. In conclusion, the large number of surgical cases covered in this study helped to identify the most common problems and complications associated with thyroid surgery under IONM. The study will form the basis for developing specific and clear guidelines both for thyroid surgery under IONM and for post-operative follow-up and monitoring.
Cell Biochem Biophys (2015) 71:1029–1033 Acknowledgments This work was supported by projects of society development plan from Changchun Science and Technology Division (12SF53) and the key support projects of science and technology from Jilin Provincial Science and Technology Department (20130206038SF).
References 1. Minahan, R. E. (2002). Intraoperative neuromonitoring. Neurologist, 8(4), 209–226. 2. Dionigi, G., Bacuzzi, A., Boni, L., et al. (2010). The technique of intraoperative neuromonitoring in thyroid surgery. Surgical Technology International, 19, 25–37. 3. Lee, C., & Stack, B. C, Jr. (2011). Intraoperative neuromonitoring during thyroidectomy. Expert Review of Anticancer Therapy, 11(9), 1417–1427. 4. Barczyn´ski, M., Randolph, G. W., Cernea, C. R., et al. (2013). External branch of the superior laryngeal nerve monitoring during thyroid and parathyroid surgery: International Neural Monitoring Study Group standards guideline statement. The Laryngoscope, 123(S4), S1–14. 5. Domosławski, P., Lukien´czuk, T., Kaliszewski, K., et al. (2013). Safety and current achievements in thyroid surgery with neuromonitoring. Advances in Clinical and Experimental Medicine, 22(1), 125–130. 6. Hayward, N. J., Grodski, S., Yeung, M., et al. (2013). Recurrent laryngeal nerve injury in thyroid surgery: a review. ANZ J Surg, 83(1–2), 15–21. 7. Higgins, T. S., Gupta, R., Ketcham, A. S., et al. (2011). Recurrent laryngeal nerve monitoring versus identification alone on postthyroidectomy true vocal fold palsy: a meta-analysis. Laryngoscope, 121(5), 1009–1017. 8. Cernea, C. R., Branda˜o, L. G., & Branda˜o, J. (2012). Neuromonitoring in thyroid surgery. Current Opinion in Otolaryngology & Head and Neck Surgery, 20(2), 125–129. 9. Sanabria, A., Silver, C. E., Sua´rez, C., et al. (2013). Neuromonitoring of the laryngeal nerves in thyroid surgery: a critical appraisal of the literature. European Archives of Oto-RhinoLaryngology, 270(9), 2383–2395. 10. Pisanu, A., Porceddu, G., Podda, M., et al. (2014). Systematic review with meta-analysis of studies comparing intraoperative neuromonitoring of recurrent laryngeal nerves versus visualization alone during thyroidectomy. Journal of Surgical Research, 188(1), 152–161. 11. Chu, K. S., Tsai, C. J., Lu, I. C., et al. (2010). Influence of nondepolarizing muscle relaxants on intraoperative neuromonitoring during thyroid surgery. Journal of Otolaryngology-Head and Neck Surgery, 39(4), 397–402. 12. Sloan, T. B. (2013). Muscle relaxant use during intraoperative neurophysiologic monitoring. Journal of Clinical Monitoring and Computing, 27(1), 35–46.
1033 13. Poveda, M. C. D., Dionigi, G., Sitges-Serra, A., et al. (2012). Intraoperative monitoring of the recurrent laryngeal nerve during thyroidectomy: a standardized approach part 2. World Journal of Endocrine Surgery, 4(1), 33–40. 14. Chiang, F.-Y., Lee, K.-W., Chen, H.-C., et al. (2010). Standardization of intraoperative neuromonitoring of recurrent laryngeal nerve in thyroid operation. World Journal of Surgery, 34(2), 223–229. 15. Randolph, G. W., Dralle, H., Abdullah, H., et al. (2011). Electrophysiologic recurrent laryngeal nerve monitoring during thyroid and parathyroid surgery: international standards guideline statement. The Laryngoscope, 121(Supplement S1), S1–S16. 16. Zakaria, H. M., Al Awad, N. A., Al Kreedes, A. S., et al. (2011). Recurrent laryngeal nerve injury in thyroid surgery. Oman Medical Journal, 26(1), 34–38. 17. Isseroff, T. F., & Pitman, M. J. (2013). Optimal management of acute recurrent laryngeal nerve injury during thyroidectomy. Current Otorhinolaryngology Reports, 1(3), 163–170. 18. Sitges-Serra, A., Fontane´, J., Duen˜as, J. P., et al. (2013). Prospective study on loss of signal on the first side during neuromonitoring of the recurrent laryngeal nerve in total thyroidectomy. British Journal of Surgery, 100(5), 662–666. 19. Dionigi, G., Boni, L., Rovera, F., et al. (2010). Postoperative laryngoscopy in thyroid surgery: proper timing to detect recurrent laryngeal nerve injury. Langenbeck’s Archives of Surgery, 395(4), 327–331. 20. Schneider, R., Randolph, G. W., Sekulla, C., et al. (2013). Continuous intraoperative vagus nerve stimulation for identification of imminent recurrent laryngeal nerve injury. Head and Neck, 35(11), 1591–1598. 21. Abadin, S. S., Kaplan, E. L., Angelos, P., et al. (2010). Malpractice litigation after thyroid surgery: the role of recurrent laryngeal nerve injuries, 1989–2009. Surgery, 148(4), 718–723. 22. Dralle, H., Sekulla, C., Lorenz, K., et al. (2008). Intraoperative monitoring of the recurrent laryngeal nerve in thyroid surgery. World Journal of Surgery, 32(7), 1358–1366. 23. Sturgeon, C., Sturgeon, T., Angelos, P., et al. (2009). Neuromonitoring in thyroid surgery, attitudes, usage patterns and predictors of use among endocrine surgeons. World Journal of Surgery, 33, 417–425. 24. Horne, S. K., Gal, T. J., & Brennan, J. A. (2007). Prevalence and patterns of intraoperative nerve monitoring for thyroidectomy. Otolaryngology-Head and Neck Surgery, 2007(136), 952–956. 25. Chen, P., Liang, F., Su, Z. B., et al. (2012). Effect of rocuronium 0.3 mg/kg (ED95) for anesthesia induction on monitoring of recurrent laryngeal nerve in patients undergoing thyroid surgery. Chinese Journal of Anesthesiology, 32(5), 525–527. 26. Xl, Meng, Wang, J., & Zhang, L. P. (2006). The effect of atracurium on facial nerve monitoring in ear surgery. Chinese Journal of Minimally Invasive Surgery, 29(2), 137–141.
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ORIGINAL PAPER
Complications and Adverse Effects Associated with Intraoperative Nerve Monitoring During Thyroid Surgery Under General Anesthesia Peng Chen • Feng Liang • Long-yun Li Guo-qing Zhao
•
Published online: 25 October 2014 Ó Springer Science+Business Media New York 2014
Abstract This study covers a large cohort of patients (3,029 cases) who underwent thyroid surgery under intraoperative nerve monitoring (IONM). Most common problems and complications associated with the surgery were identified and analyzed. On the basis of this analysis, we provide some practical advices and suggestions which specialists in the field will find useful in their surgical practice. The data will help in developing clear surgical guidelines for thyroid surgery with IONM and for postoperative follow-up and monitoring. Keywords Thyroid surgery Intraoperative nerve monitoring Anesthesia
Introduction Intraoperative nerve monitoring (IONM) in the course of surgical operations has been developed in recent years [1]. Among other applications, the technique is widely used for monitoring and protecting the recurrent laryngeal nerve (RLN) during the thyroid surgery, thus reducing the probability of RLN injury [2–6]. Despite general recognition of the benefits of IONM, the advantages of this approach for thyroid surgery are still debatable. A number of studies and systematic reviews point to statistically marginal advantages of IONM in
P. Chen F. Liang L. Li (&) G. Zhao (&) Department of Anesthesiology, China-Japan Union Hospital of Jilin University, No. 126 Xiantai Street, Changchun 130033, China e-mail: [email protected] G. Zhao e-mail: [email protected]
comparison with visualization alone [7–10]. These conclusions might be related to the fact that practical implementation of IONM technique is associated with a number of problems. Despite the lack of convincing evidences of the IONM’s advantages during thyroid surgery at present time, there are no doubts that this technique, once perfected, will be beneficial for patients. One of the problems the IONM is facing is the potential interferences caused by drugs used for initiating and maintaining anesthesia [11, 12]. The anesthesia during surgery is a major disturbance factor for monitoring process. In this article, we review the use of anesthesia in thyroidectomy in 3,029 surgeries performed in September 2011–November 2013. The study aims to assess the complications related to anesthesia before and after thyroid surgery and evaluate the potential standardization of anesthesia technique under IONM in thyroid surgery. The findings might contribute to the existing efforts [13–15] in developing the clear surgical guidelines for thyroid surgery under IONM monitoring.
Materials and Methods A total of 3,029 patients (461 males and 2,568 females) were submitted to thyroid surgery to China–Japan Union Hospital from September 2011 to November 2013 under general anesthesia. Patient’s age ranged from 19 to 71 and weight ranged from 37 to 109 kg. Out of the total, 2,313 patients underwent the thyroid cancer surgery. The secondary surgery was performed in 738 cases and the third surgery in 189 cases. Concurrent preoperative injuries of RLN were encountered in 213 cases, and 11 cases developed the injury in the other nerves which were classified as ASA II–III.
123
1030
Cell Biochem Biophys (2015) 71:1029–1033
Fig. 1 The special mat for thyroid surgery positioned under the patient’s neck
Anesthesia and Surgery Patients were injected with 1 mg Penehyclidine Hydrochloride 30 min before surgery. Intraoperative monitoring included noninvasive blood pressure (NIBP) monitoring, electrocardiography (ECG), oxygen saturation (SpO2), end-tidal carbon dioxide partial pressure (PetCO2 oximetry), and capnography. Patients were positioned for thyroid surgery (Fig. 1) and administered with intravenous Midazolam propofol at 2 lg/kg, sufentanil (0.5 lg/kg) and rocuronium bromide (0.3 lg/kg) (Lot H20040423, Organon Inc., The Netherlands) (Fig. 1). Tracheal catheters were inserted (Medtronic Xomed Corporation, United States). Conventional laryngoscopy with fiberoptic bronchoscopy was performed in 576 cases, and for all other patients the video laryngoscope was used. Cooper scoring was assessed, and blood pressure and pulse changes were recorded in order to evaluate the tracheal intubation conditions. Maintenance of anesthesia was achieved by sevoflurane–oxygen inhalation (50 % NO, 50 % O2), and the depth of anesthesia was kept at 1.2–1.4 MAC by adjusting sevoflurane. NIM-Response 2.0 or NIM-Response 3.0 electrical instruments (Medtronic Xomed, USA) were used for neuromuscular monitoring. After surgery, we gradually modulated the anesthesia into a lower level and maintained its depth at around 0.1 MAC manually. Then, we tried to wake up patients and wait until the breathing was restored. Patients were sent back to the surgery recovery room after the conditions were stable. At 24 h post-operatively, overall patient outcome after the treatment with IONM was recorded.
Results The endotracheal tube was successfully inserted in all patients, and all the intubation conditions were met with minimal adverse effects encountered. The vagus nerve and
123
Table 1 The complication encountered before and after surgery Pre-surgery
Number of cases
Bucking
227
Deep tracheal catheter placement
129
Tracheal catheter rotation
38
Over-secretion and unstable signal
19
Unstable blood flow dynamics
147
Oral mucosa injury
1
Post-surgery
Number of cases
Throat pain
176
Pharyngeal discomfort
234
Voice hoarse and joint half-dislocation
19
Inhaled pneumonia
3
Dry eye syndrome
21
Ear and neck numbness
21
Conjunctival congestion
49
the RLN signal (signal V/R) amplitude met all monitoring requirements and all patients underwent surgery successfully. Preoperative and post-operative problems encountered during the treatment of all patients in this study were analyzed, allocated into different categories and summarized in Table 1.
Discussion In recent years, with the rising incidence of thyroid disease, RLN injury became a very common complication during the thyroid surgery, and various practical aspects of this problem are receiving a significant attention of both medical researchers and practitioners [16–21]. IONM has been used successfully as a new revolutionary technology for identification of the RLN in thyroid surgery [22, 23]. Despite the advantages, the value of IONM still remains
Cell Biochem Biophys (2015) 71:1029–1033
Fig. 2 Comparison of the recurrent laryngeal nerve electromyographic signals generated under different anesthesia induction methods
debatable among endocrine surgeons. In this article, we aimed to present the current knowledge on the subject and summarize our experience for the anesthesia during IONM in thyroidectomy, as well as discuss the approaches to standardization of anesthesia under IONM in this surgical procedure. The induction phase is the key step of the anesthesia when thyroid surgery with IONM is performed. Unfortunately, the endotracheal intubation is very difficult to perform when non-depolarizing muscle relaxants are used. Since muscle relaxants, even in residual quantities, can interfere with nerve monitoring process [24, 25] and trigger the generation of false-positive RLN signal, thyroid surgeons tend to avoid the use of these agents. Common approach to this problem is to use depolarizing relaxant induction or no muscle relaxant induction. In China, however, due to large number of cases and shortage of specialized anesthesiologists, the inherent weakness of using depolarizing relaxant induction and the operational difficulty without muscle relaxant induction make this approach not widely accepted among specialists. In our previous study [25], we recommended to induce anesthesia by double doses of ED95 rocuronium bromide and slightly increased the dosage of the general anesthetics and analgesics. We compared the amplitudes of neuromuscular monitoring between the high doses of ED95 rocuronium bromide and sevoflurane inhalation. The former drug was found to fully satisfy all the requirements for the surgery [26] (Fig. 2). For the endotracheal tube placement under IONM, we recommended to set the patient position first (as shown on Fig. 1) and then perform tracheal intubation. In the traditional approach, the patient is adjusted to the thyroid gland position after intubation is done. This may result in the misplacement of tracheal intubation and the inaccurate measurement of the signal. Furthermore, the use
1031
of video laryngoscope is highly recommended during intubation. If video laryngoscope is not used, the intubation line needs to be marked first. The longitudinal mark line should be kept in the center position, and the horizontal mark line should be intersected with the vocal for the best positioning of the fiberoptic bronchoscope (Fig. 3). If the airway resistance increases during the intubation process, it might be caused by anesthesia being too shallow. Deep anesthesia was suggested for the induction phase. The recommended dosage for induction includes 2 lg/kg of midazolam propofol, followed by 0.5 lg/kg of sufentanil and 0.3 lg/kg of rocuronium bromide [25]. In addition, due to the relatively simple trachea cannula type produced by Medtronic Xomed Company, the available models might not match the endotracheal tube. The cuff pressure should not be too high in order to protect the tracheal mucosa. During the maintenance phase of anesthesia, it is recommended to avoid the use of the muscle relaxant under IONM in thyroid surgery due to extremely low requirements for the muscle relaxation [25]. Sevoflurane was used to maintain breath depth at around 1.2–1.6 MAC if the endtidal gas monitoring equipment was available. This depth of anesthesia should not only meet the standard requirements but also produce some central muscle relaxation effects without any signal side effect [26]. If there is no end-tidal gas monitoring equipment, anesthesiologist can use the intravenous general anesthesia or combined intravenous anesthesia. The principles are to keep the depth of anesthesia not too shallow and maintain it as smooth as possible. During the maintenance phase of anesthesia, it is also important to not attenuate the depth of anesthesia as early as possible. Intraoperative hemodynamic instability in surgery is directly related to the unstable depth of anesthesia. The direct inhibition effect of intravenous anesthesia drug on myocardium and the long fasting time can cause insufficient cycle capacity and decrease of blood pressure. Some anesthesia specialists prefer to use shallow anesthesia method to obtain relatively good blood flow dynamics indicators and do not use muscle relaxants during the maintenance phase. It is possible to have deep anesthesia and then reduce anesthesia fast, which may lead to unstable blood flow dynamics. We recommended to use end-breathing gas monitoring or BIS monitoring in order to keep the anesthesia depth stable, under the management of experienced anesthesiologist. After surgery, the patients should regain consciousness naturally in order to reduce the anesthesia complications such as restlessness. We learned that we should keep the anesthesia stable before the end of surgery, and then gradually reduce the depth of anesthesia once surgery is finished. In general, the depth of anesthesia can be reduced to about 0.1 MAC after 10 min. When the depth of anesthesia is around 0.2–0.3 MAC, the patient should not be
123
1032
Cell Biochem Biophys (2015) 71:1029–1033
Fig. 3 The use of video laryngoscope for tracheal intubation
stimulated, otherwise restlessness can be caused very easily. When anesthetic depth is dropped below 0.1 MAC, we can control breathing manually, restore the breathing, wake up patients, and then perform the tracheal extubation and encourage the patient to cough. If there is any cough or breath before the anesthetic depth was dropped below 0.1 MAC, we can directly control breathing manually, but should not irritate the patient in order to prevent iatrogenic throat pain and discomfort. Sometimes the neuromuscular monitoring signal weakens or disappears during the surgery. Except for operative reasons, the common causes include the overdose of non-depolarizing muscle relaxants, endotracheal tube misplacement (too deep, too shallow, or rotated), loop electrode going off, machine malfunctions, and a number of other less common problems. The first three are the most common reasons for the weakening or disappearing of signal. The causes of unstable signal can be related to the airway over-secretion if the patients had been in shallow anesthesia state for a long time. Also, the use of non-anti-choline class drugs before the surgery or long surgery time can lead to the airway over-secretion and cause the signal instability. Furthermore, inappropriate use of electric knife and detection electrode can interfere with the signal from other muscle groups and increase the instability of signal. The use of video laryngoscope requires proper training of the practitioners. Improper use of video laryngoscopes can lead to the post-operative hoarseness and half-dislocation of cricoarytenoid joint. Video laryngoscope is different from usual laryngoscope since the latter has 0° lens.
123
In our cohort, one of the patients suffered lateral pharyngeal wall mucosal injury and bleeding due to the improper use of video laryngoscopes. In addition, the small number of available endotracheal tube models produced by Medtronic Xomed that are used for RLN monitoring might cause additional problems. Our experience suggests that we should encourage patients to cough immediately after extubation. In addition, post-surgery branchofiberoscope examination is important and can help to identify the problem of arytenoid subluxation. Conjunctival hyperemia and dry eye syndrome sometimes happened as a result of surgery. They might have been caused by the long operation time and improper sterile bedding which leads to poor eyelid closure. In the study group, there were 21 patients with post-surgery dry eye syndrome, of which 17 were ‘‘double eyelid’’ surgery patients. The use of eye-patch or eye ointment is therefore recommended. The facial numbness is caused by overstretching of the head. Reducing the operating time as much as possible and explaining clearly to the patients before operation that facial numbness may appear after the surgery are very important for reducing the risk of this complication and avoiding the patient’s dissatisfaction. In conclusion, the large number of surgical cases covered in this study helped to identify the most common problems and complications associated with thyroid surgery under IONM. The study will form the basis for developing specific and clear guidelines both for thyroid surgery under IONM and for post-operative follow-up and monitoring.
Cell Biochem Biophys (2015) 71:1029–1033 Acknowledgments This work was supported by projects of society development plan from Changchun Science and Technology Division (12SF53) and the key support projects of science and technology from Jilin Provincial Science and Technology Department (20130206038SF).
References 1. Minahan, R. E. (2002). Intraoperative neuromonitoring. Neurologist, 8(4), 209–226. 2. Dionigi, G., Bacuzzi, A., Boni, L., et al. (2010). The technique of intraoperative neuromonitoring in thyroid surgery. Surgical Technology International, 19, 25–37. 3. Lee, C., & Stack, B. C, Jr. (2011). Intraoperative neuromonitoring during thyroidectomy. Expert Review of Anticancer Therapy, 11(9), 1417–1427. 4. Barczyn´ski, M., Randolph, G. W., Cernea, C. R., et al. (2013). External branch of the superior laryngeal nerve monitoring during thyroid and parathyroid surgery: International Neural Monitoring Study Group standards guideline statement. The Laryngoscope, 123(S4), S1–14. 5. Domosławski, P., Lukien´czuk, T., Kaliszewski, K., et al. (2013). Safety and current achievements in thyroid surgery with neuromonitoring. Advances in Clinical and Experimental Medicine, 22(1), 125–130. 6. Hayward, N. J., Grodski, S., Yeung, M., et al. (2013). Recurrent laryngeal nerve injury in thyroid surgery: a review. ANZ J Surg, 83(1–2), 15–21. 7. Higgins, T. S., Gupta, R., Ketcham, A. S., et al. (2011). Recurrent laryngeal nerve monitoring versus identification alone on postthyroidectomy true vocal fold palsy: a meta-analysis. Laryngoscope, 121(5), 1009–1017. 8. Cernea, C. R., Branda˜o, L. G., & Branda˜o, J. (2012). Neuromonitoring in thyroid surgery. Current Opinion in Otolaryngology & Head and Neck Surgery, 20(2), 125–129. 9. Sanabria, A., Silver, C. E., Sua´rez, C., et al. (2013). Neuromonitoring of the laryngeal nerves in thyroid surgery: a critical appraisal of the literature. European Archives of Oto-RhinoLaryngology, 270(9), 2383–2395. 10. Pisanu, A., Porceddu, G., Podda, M., et al. (2014). Systematic review with meta-analysis of studies comparing intraoperative neuromonitoring of recurrent laryngeal nerves versus visualization alone during thyroidectomy. Journal of Surgical Research, 188(1), 152–161. 11. Chu, K. S., Tsai, C. J., Lu, I. C., et al. (2010). Influence of nondepolarizing muscle relaxants on intraoperative neuromonitoring during thyroid surgery. Journal of Otolaryngology-Head and Neck Surgery, 39(4), 397–402. 12. Sloan, T. B. (2013). Muscle relaxant use during intraoperative neurophysiologic monitoring. Journal of Clinical Monitoring and Computing, 27(1), 35–46.
1033 13. Poveda, M. C. D., Dionigi, G., Sitges-Serra, A., et al. (2012). Intraoperative monitoring of the recurrent laryngeal nerve during thyroidectomy: a standardized approach part 2. World Journal of Endocrine Surgery, 4(1), 33–40. 14. Chiang, F.-Y., Lee, K.-W., Chen, H.-C., et al. (2010). Standardization of intraoperative neuromonitoring of recurrent laryngeal nerve in thyroid operation. World Journal of Surgery, 34(2), 223–229. 15. Randolph, G. W., Dralle, H., Abdullah, H., et al. (2011). Electrophysiologic recurrent laryngeal nerve monitoring during thyroid and parathyroid surgery: international standards guideline statement. The Laryngoscope, 121(Supplement S1), S1–S16. 16. Zakaria, H. M., Al Awad, N. A., Al Kreedes, A. S., et al. (2011). Recurrent laryngeal nerve injury in thyroid surgery. Oman Medical Journal, 26(1), 34–38. 17. Isseroff, T. F., & Pitman, M. J. (2013). Optimal management of acute recurrent laryngeal nerve injury during thyroidectomy. Current Otorhinolaryngology Reports, 1(3), 163–170. 18. Sitges-Serra, A., Fontane´, J., Duen˜as, J. P., et al. (2013). Prospective study on loss of signal on the first side during neuromonitoring of the recurrent laryngeal nerve in total thyroidectomy. British Journal of Surgery, 100(5), 662–666. 19. Dionigi, G., Boni, L., Rovera, F., et al. (2010). Postoperative laryngoscopy in thyroid surgery: proper timing to detect recurrent laryngeal nerve injury. Langenbeck’s Archives of Surgery, 395(4), 327–331. 20. Schneider, R., Randolph, G. W., Sekulla, C., et al. (2013). Continuous intraoperative vagus nerve stimulation for identification of imminent recurrent laryngeal nerve injury. Head and Neck, 35(11), 1591–1598. 21. Abadin, S. S., Kaplan, E. L., Angelos, P., et al. (2010). Malpractice litigation after thyroid surgery: the role of recurrent laryngeal nerve injuries, 1989–2009. Surgery, 148(4), 718–723. 22. Dralle, H., Sekulla, C., Lorenz, K., et al. (2008). Intraoperative monitoring of the recurrent laryngeal nerve in thyroid surgery. World Journal of Surgery, 32(7), 1358–1366. 23. Sturgeon, C., Sturgeon, T., Angelos, P., et al. (2009). Neuromonitoring in thyroid surgery, attitudes, usage patterns and predictors of use among endocrine surgeons. World Journal of Surgery, 33, 417–425. 24. Horne, S. K., Gal, T. J., & Brennan, J. A. (2007). Prevalence and patterns of intraoperative nerve monitoring for thyroidectomy. Otolaryngology-Head and Neck Surgery, 2007(136), 952–956. 25. Chen, P., Liang, F., Su, Z. B., et al. (2012). Effect of rocuronium 0.3 mg/kg (ED95) for anesthesia induction on monitoring of recurrent laryngeal nerve in patients undergoing thyroid surgery. Chinese Journal of Anesthesiology, 32(5), 525–527. 26. Xl, Meng, Wang, J., & Zhang, L. P. (2006). The effect of atracurium on facial nerve monitoring in ear surgery. Chinese Journal of Minimally Invasive Surgery, 29(2), 137–141.
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