Implementation of a Standardized Protocol for Recurrent Laryngeal Nerve Monitoring Reduces False Negative Results during Neck Surgery: A Quality Control Case Study

Implementation of a Standardized Protocol for Recurrent Laryngeal Nerve Monitoring Reduces False Negative Results during Neck Surgery: A Quality Control Case Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Implementation of a Standardized Protocol for Recurrent Laryngeal Nerve Monitoring Reduces False Negative Results during Neck Surgery: A Quality Control Case Study Colby Simmons, Julio Montejano, Lauren Eagleston, Scott Cao, Alexander M. Kaizer, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3304342/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: Recurrent laryngeal nerve (RLN) injury during neck surgery can cause significant morbidity related to vocal cord (VC) dysfunction. VC electromyography (EMG) is used to aid in identification of the RLN and can reduce the probability of inadvertent surgical injury. Errors in placement of specialized EMG endotracheal tubes (ETT) can result in unreliable signals, false-negative responses, or no response when stimulating the RLN. We describe a novel educational protocol developed to optimize uniformity in placement of ETTs to improve reliability of RLN monitoring. Methods: Intraoperative neuromonitoring database was queried for all neck surgeries requiring RLN monitoring. Data points extracted for all cases requiring EMG monitoring for neck procedures. Free running and stimulated EMG were monitored and continuously recorded by a certified technologist. Alerts were compared between 2013-14 and 2015-18 using a two-sample test of proportions. Results: Significant reductions in alerts were demonstrated after protocol implementation (7.5% pre-implementation to 2.1% post). Alerts were compared between 2013-14 (overall alert rate of 1.8%, pre-implementation period) and 2015-18 (overall alert rate of 2.8%, post-implementation period). Conclusion: Protocolization for placement of EMG-ETT improved accuracy in EMG monitoring. In the follow-up cohort of 1,080 patients, use of this protocol continued to reduce the rate of alerts related to ETT malposition confirming the sustainability of this intervention through routine education. Risk of nerve injury is reduced when the rate of alerts is minimized. Scheduled or continuous protocol education of anesthesia personnel should continue to ensure compliance with protocol. Figures Figure 1 Figure 2 Figure 3 Introduction During head and neck surgery, the Recurrent Laryngeal Nerve (RLN) is one vital structure at risk of injury. Significant morbidity and mortality as a result of RLN injury is observed in the form of vocal cord dysfunction, with complications ranging from transient voice changes and shortness of breath to vocal cord paralysis and fatal airway obstruction. The reported incidence of RLN Palsy (RLNP) ranges from 0%-7.1% and for transient RLNP to 0%-11%.[ 1 ]. In the United States, between 2011 and 2015 there was an ~ 60% increase in the number of thyroidectomy surgeries completed[ 2 ]. With the rising numbers of neck surgeries such as thyroidectomy, vocal cord electromyography (EMG) is more important than ever in preventing nerve injury[ 2 ]. Although visual nerve identification remains the gold standard for injury prevention, the combination of vocal cord EMG with visual nerve identification is becoming more common. Vocal cord EMG, introduced in the 1970’s, is physician managed and requires subspecialty training in intra-operative neurophysiologic monitoring (IONM)[ 3 ]. EMG offers added protection for the patient and surgeon as its technology can be used to confirm the identity of the nerve after visual inspection as well as intermittent monitoring for accidental damage. This technology can also be used during anterior cervical spine surgery. However, literature supporting the utilization of IONM has been mixed since introduction of the technology. Numerous independent studies and systematic reviews are inconclusive in its use as standard of care with no significant clinical differences reported[ 4 , 5 ]. A recent Cochrane review from 2019 similarly reported finding no significant difference in the rates of RLNP between IONM and the visual identification group[ 6 ]. The consensus was that more high-quality, randomized control trials were needed before IONM can be designated as standard of care. On the contrary, multiple recent studies have shown the effectiveness of IONM including a 2017 meta-analysis of 34 original studies that found IONM to be effective in decreasing RLN injury during thyroidectomy[ 7 ]. More recent, studies have also found significant differences supporting the use of IONM versus no IONM, in prevention of vocal cord palsy[ 8 , 9 ]. IONM of the RLN can be accomplished through visual interpretation of EMG recordings generated by an endotracheal tube that is appropriately positioned and in contact with bilateral vocal cords. At our institution where this protocol was developed, the NIM Trivantage ™ (Medtronic, Minneapolis, MN) EMG endotracheal tube (ETT) was utilized as the recording device. Electrodes are embedded within the ETT and it is positioned such that these electrodes remain in constant contact with the bilateral vocal cords throughout surgery until completion[ 10 ]. Correct placement of the tube, along with other recommendations such as avoidance of lubrication of the ETT, avoidance of topicalization of the vocal cords with local anesthetic (LTA), avoidance of the use of long acting neuromuscular blockers, and use of anticholinergic agents to dry secretions when excess saliva is observed during video laryngoscopy to avoid the salt bridging phenomenon, is paramount in increasing the accuracy of EMG monitoring and decreasing the incidence of alerts. Alerts as they pertain to RLN monitoring are failures to obtain an EMG response when a surgeon has identified or directly stimulated the RLN. False alerts increase the likelihood of clinically significant post-operative deficits. Standardized practices and protocols are necessary to minimize inappropriate variations among the anesthesia care team, which can lead to decreased efficacy of IONM and ultimately patient injury. Randolph et al 2011, produced an international standards guideline that has set the framework for consistent IONM[ 11 ]. In this novel project we developed and successfully implemented a protocol for correct placement of the specialized ETT. Implementation of this protocol led to higher quality and more reliable neuromonitoring during these procedures. We have maintained high levels of adherence to the protocol through systematic re-education at department meetings. As a result of the improved efficacy of ETT placement and quality of monitoring, we believe our project could be implemented at other institutions with ease. Methods The standardized protocol for correct placement of the specialized ETT was designed using available literature, case reports, statements from different scientific societies and expert opinion. The protocol included step by step instructions for the preparation of equipment prior to placement of the ETT, considerations during placement and specific instructions for securing and verifying ETT placement. Pharmacologic and anesthetic recommendations and contraindications were also included (Fig. 1 ). The protocol was introduced to clinical practice in 2013–2014. Multiple and recurrent educational strategies for training of anesthesia personnel were used to ensure all team members had proper training and access to the protocol. After the first round of education, the protocol was distributed electronically and physical copies were placed in all anesthetizing locations. In addition, all certified IONM technologists had a copy of the protocol available for easy consultation. Personalized training was provided to new team members. Colorado Multiple Institutional Review Board (COMIRB) approval was obtained prior to the initiation of this study. The University of Colorado Hospital (UCH) electronic medical records systems (Centricity Anesthesia from 2009–2010, EPIC from 2011–2014) and the UCH intra-operative neuromonitoring database were queried to identify all surgical cases that would be appropriate for inclusion in this study. Inclusion criteria included surgeries of the neck (thyroidectomies, parathyroidectomies, and/or neck dissections) between January 2009 and December 2018, that required intra-operative monitoring of the RLN via free-running and stimulated EMG. EMG responses were continuously monitored and recorded by a certified IONM technologist and supervised by an attending neuroanesthesiologist. A chi-square test of proportions was used to calculate the risk difference of the group prior to protocol implementation (combined 4 years: 2009,2010,2011,2012) and that of the groups after protocol implementation (combined years :2013 and 2014). SAS version 9.4 was used to analysis the results. A significance level of 0.05 was used. In order to determine the efficacy of the implemented protocol, a follow-up data analysis was performed. The follow up period was defined as the time after implementation of the standardized protocol (2015–2018). During the follow-up period EPIC and the UCH intra-operative neuromonitoring database were queried. The same inclusion criteria were used. In summary, this retrospective study extracted data relating to the number of neck procedures requiring RLN monitoring, C-MAC use, and alerts prior to protocol implementation (2009 and 2012), immediately after implementation (2013–2014), and after the protocol became standard of care (follow-up period 2015–2018). The purpose was to evaluate if incorporation of the protocol as standard of care resulted in any significant changes since the initial introduction of the protocol in 2013 and 2014. Summaries are presented as count (percentage) or average percentage. A two-sample test of proportions was used to compare the 2013–2014 and 2015–2018 periods to detect any significant change in the rate of alerts. The analysis was completed using R v3.6.0 and the figure was created in Excel. Results A total of 607 patients underwent intra-operative RLN monitoring between January 2009 and December 2014. During this time, there was a 622% increase in the number of cases in which intra-operative RLN monitoring was utilized, from 27 cases in 2009 to 168 cases in 2014. The introduction of a standardized protocol for correct placement was implemented in 2013 and 2014. There was a significant association of the standardized protocol with reduced proportion of alerts. The overall proportion of alerts in the non-protocolized group was 7.5% (4%,11%). The overall proportion of alerts in the protocolized group was 2.1% (0.8%,5.7%). The risk difference was determined to be 5.36% (1.9%,8.8%). Prior to the introduction of a standardized protocol there were alerts in 15% of cases in 2009 and 7.8% in 2012. After the implementation of the protocol and its establishment as standard of care, the rate of alerts decreased to 1.5-3% between 2013–2018 (Fig. 2 ). Specifically, the overall proportion of alerts was 1.8% (6/327) in 2013–2014 and 2.8% (30/1080) in 2015–2018, which did not represent a significant change (increase of 1% [95% CI:-2.9–1.0%], p = 0.456).The use of C-MAC increased from 15% (4/27) in 2009 to 95% (89/94) by 2012. C-MAC use was 81% (264/327) between 2013–2014 during the introduction of the protocol. After the implementation of the protocol as standard of care between 2015–2018, the use of C-MAC was 97% (1048/1080) (Fig. 3 ). Discussion Accurate and precise placement of EMG ETTs is essential to provide reliable and consistent data to surgeons in real-time as they begin their approach to or dissect in direct approximation to the RLN. Surgeon complaints of variable or low positive predictive value (PPV) of IONM has hindered its broader utilization[1]. With this study, we attempted to minimize alerts by improving correct placement of EMG ETTs through direct visualization with video laryngoscopy and optimization of anesthesia technique. Despite significant increases in staffing numbers, provider turnover, and number of cases performed, absolute utilization of C-MAC ® increased from 15% to 91% during the implementation period. This was associated with a significant decrease in alerts during neck surgeries. This effect continued to be observed at our institution years after the implementation of this protocol as shown by a statistically insignificant difference in the percentage of alerts in the implementation and post implementation cohorts. Interval education of anesthesia providers at large meetings of faculty (Grand Rounds, departmental meetings, etc) likely had an impact in reducing gradual decline in adherence to the protocol. At the same time, laminated, color-printed cards with detailed, photographic descriptions of the protocol were made available in all operating rooms in our facility. This reference material served as a reminder for those practitioners who didn’t regularly participate in the care of patients having neck surgery. The neuroanesthesia faculty served as a core group of experts in this protocol and continue to be available for troubleshooting and teaching. The neuromonitoring technologists at our institution were also involved in the implementation of this protocol and their buy-in increased project success. It is difficult to definitively identify which of the interventions explained above was responsible for the effects observed. As was previously stated in addition to the implementation of video laryngoscopy as the gold standard for placement of ETT in these cases several recommendations were made. That being said the focus of the protocol and the main focus of staff education was on the use of video laryngoscopy for appropriate placement of the ETT. One variable that we could not account for was practitioner choice of size of the EMG ETT, though recommendations were made in the protocol to adhere to a binary size system based on gender that recommended 7.0 mm ETT and 8.0mm ETT for female and male patients respectively. This variable was not controlled for and has the potential to affect the reliability of EMG monitoring for these cases if practitioners opted to downsize ETT due to diameter-tracheal mismatch. Other possible confounding variables include length of surgery, amount of patient secretions, equipment malfunction or failure and surgeon misidentification of neural tissue could account for the persistent rate of alerts. These factors are difficult to eliminate and would pose a challenge to study in isolation as they could potentially lead to patient harm. Future studies could be aimed at identifying whether this intervention can lead to improvement in the delivery of quality care, patient outcomes, reduction in clinical harm and increased trust and reliance on IONM. Despite these limitations, given the reduction in alerts during the implementation period and the persistent low incidence of alerts in the post-implementation period, it is clear that protocolizing the placement of EMG ETT with compulsory verification using video laryngoscope as well anesthetic technique during head and neck surgery leads to a decrease in IONM alerts. Declarations Conflicts of Interest: None Details of Prior presentation: Presented at ASA 2019 as Oral Poster Presentation Ethics approval and consent to participate Approval was obtained from Institutional Review Board (Colorado Multiple Institutional Review Board [COMIRB]) at the University of Colorado Denver, USA. The need for patient informed consent was waived or exempted by the Colorado Multiple Institutional Review Board [COMIRB]. All relevant methods were undertaken in strict accordance with departmental and institutional regulations. Consent for publication Not applicable Availability of data and materials All data are available upon request. Any request for additional information should be directed to the corresponding author. Competing interests The authors have no competing interests to disclose. Funding The study was conducted using Departmental funds. Authors' contributions C.S. designed and led the study, analyzed the data and wrote the manuscript, J.M. wrote the manuscript and analyzed the data, L.E. wrote the manuscript and analyzed the data, S.C. analyzed the data and wrote the manuscript, A.K. analyzed the data and wrote the manuscript, L.J. analyzed the data and wrote the manuscript, A.O. analyzed the data and wrote the manuscript, C.C. designed and led the study, analyzed the data and wrote the manuscript. Acknowledgements Not applicable References Dralle H, et al. Intraoperative monitoring of the recurrent laryngeal nerve in thyroid surgery. World J Surg. 2008;32(7):1358–66. Sosa JA et al. Increases in thyroid nodule fine-needle aspirations, operations, and diagnoses of thyroid cancer in the United States. Surgery, 2013. 154(6): p. 1420-6; discussion 1426-7. Zhang D, et al. Neural monitoring in thyroid surgery is here to stay. Gland Surg. 2020;9(Suppl 1):S43–s46. Malik R, Linos D. Intraoperative Neuromonitoring in Thyroid Surgery: A Systematic Review. World J Surg. 2016;40(8):2051–8. Pisanu A, et al. Systematic review with meta-analysis of studies comparing intraoperative neuromonitoring of recurrent laryngeal nerves versus visualization alone during thyroidectomy. J Surg Res. 2014;188(1):152–61. Cirocchi R, et al. Intraoperative neuromonitoring versus visual nerve identification for prevention of recurrent laryngeal nerve injury in adults undergoing thyroid surgery. Cochrane Database Syst Rev. 2019;1:Cd012483. Bai B, Chen W. Protective Effects of Intraoperative Nerve Monitoring (IONM) for Recurrent Laryngeal Nerve Injury in Thyroidectomy: Meta-analysis. Sci Rep. 2018;8(1):7761. Wojtczak B, et al. Voice quality preservation in thyroid surgery with neuromonitoring. Endocrine. 2018;61(2):232–9. Kartal K et al. Intraoperative Neuromonitoring in Thyroid Surgery: An Efficient Tool to Avoid Bilateral Vocal Cord Palsy . Ear Nose Throat J, 2020: p. 145561320906325. Julien N, et al. Intraoperative laryngeal nerve monitoring during thyroidectomy and parathyroidectomy: A prospective study. Eur Ann Otorhinolaryngol Head Neck Dis. 2012;129(2):69–76. Randolph GW, et al. Electrophysiologic recurrent laryngeal nerve monitoring during thyroid and parathyroid surgery: international standards guideline statement. Laryngoscope. 2011;121(Suppl 1):S1–16. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3304342","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":233645394,"identity":"eb0c3bbe-0f18-4322-accb-c5515626316d","order_by":0,"name":"Colby Simmons","email":"data:image/png;base64,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","orcid":"","institution":"University of Colorado School of Medicine, Anschutz Medical Campus","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Colby","middleName":"","lastName":"Simmons","suffix":""},{"id":233645395,"identity":"79ca5fbe-8f04-4bf4-82af-ab76d6f95b32","order_by":1,"name":"Julio Montejano","email":"","orcid":"","institution":"University of Colorado School of Medicine, Anschutz Medical Campus","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Julio","middleName":"","lastName":"Montejano","suffix":""},{"id":233645396,"identity":"05d521c3-cec6-403e-9085-31bf9286c553","order_by":2,"name":"Lauren Eagleston","email":"","orcid":"","institution":"US Anesthesia Partners","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Lauren","middleName":"","lastName":"Eagleston","suffix":""},{"id":233645397,"identity":"840a0675-064d-4b8c-ad04-a0bca0af3551","order_by":3,"name":"Scott Cao","email":"","orcid":"","institution":"Massachusetts General Hospital, Harvard School of Medicine","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Scott","middleName":"","lastName":"Cao","suffix":""},{"id":233645398,"identity":"123d6086-11d8-4a70-813c-28a67188ba44","order_by":4,"name":"Alexander M. Kaizer","email":"","orcid":"","institution":"University of Colorado-Anschutz Medical Campus, Colorado School of Public Health","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Alexander","middleName":"M.","lastName":"Kaizer","suffix":""},{"id":233645399,"identity":"9e0afda7-b4af-4f6a-992c-ed021b9c5f71","order_by":5,"name":"Leslie Jameson","email":"","orcid":"","institution":"University of Colorado School of Medicine, Anschutz Medical Campus","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Leslie","middleName":"","lastName":"Jameson","suffix":""},{"id":233645400,"identity":"d057b243-a63d-4fc1-8efe-8f43e7c4a09d","order_by":6,"name":"Anthony Oliva","email":"","orcid":"","institution":"University of Colorado School of Medicine, Anschutz Medical Campus","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Anthony","middleName":"","lastName":"Oliva","suffix":""},{"id":233645401,"identity":"485519e3-80f8-4c6c-843d-d71db5c7d5b0","order_by":7,"name":"Claudia F. Clavijo","email":"","orcid":"","institution":"University of Colorado School of Medicine, Anschutz Medical Campus","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Claudia","middleName":"F.","lastName":"Clavijo","suffix":""}],"badges":[],"createdAt":"2023-08-28 18:29:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3304342/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3304342/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":43307409,"identity":"ccd697e0-3977-4023-a533-de1e64354169","added_by":"auto","created_at":"2023-09-18 16:16:21","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":369668,"visible":true,"origin":"","legend":"\u003cp\u003eExample of the EMG ETT placement protocol made available to all Anesthesia providers.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-3304342/v1/f07de4dcdf5410692864f4ee.png"},{"id":43307397,"identity":"039d921c-5d40-463a-a5af-f432a361852f","added_by":"auto","created_at":"2023-09-18 16:16:21","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":37128,"visible":true,"origin":"","legend":"\u003cp\u003eAlerts reported following initial implementation of ETT placement protocol and establishment as standard of care 2013-2014.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-3304342/v1/77e6a95b7ca2cae961a7f742.png"},{"id":43307398,"identity":"6ee89eb3-53a1-4256-a33c-193946385ab6","added_by":"auto","created_at":"2023-09-18 16:16:21","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":39304,"visible":true,"origin":"","legend":"\u003cp\u003eAlerts reported in the follow-up cohort between 2015-2018, performed after the implementation of the ETT placement protocol.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-3304342/v1/b6301b5a332cd7b72ca52393.png"},{"id":54740103,"identity":"2f601045-6c05-4ce2-82aa-f473c20a887a","added_by":"auto","created_at":"2024-04-16 05:38:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":765103,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3304342/v1/c28aeb0a-ba67-407d-80b0-e96cca67810f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Implementation of a Standardized Protocol for Recurrent Laryngeal Nerve Monitoring Reduces False Negative Results during Neck Surgery: A Quality Control Case Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eDuring head and neck surgery, the Recurrent Laryngeal Nerve (RLN) is one vital structure at risk of injury. Significant morbidity and mortality as a result of RLN injury is observed in the form of vocal cord dysfunction, with complications ranging from transient voice changes and shortness of breath to vocal cord paralysis and fatal airway obstruction. The reported incidence of RLN Palsy (RLNP) ranges from 0%-7.1% and for transient RLNP to 0%-11%.[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. In the United States, between 2011 and 2015 there was an ~\u0026thinsp;60% increase in the number of thyroidectomy surgeries completed[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. With the rising numbers of neck surgeries such as thyroidectomy, vocal cord electromyography (EMG) is more important than ever in preventing nerve injury[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Although visual nerve identification remains the gold standard for injury prevention, the combination of vocal cord EMG with visual nerve identification is becoming more common. Vocal cord EMG, introduced in the 1970\u0026rsquo;s, is physician managed and requires subspecialty training in intra-operative neurophysiologic monitoring (IONM)[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. EMG offers added protection for the patient and surgeon as its technology can be used to confirm the identity of the nerve after visual inspection as well as intermittent monitoring for accidental damage. This technology can also be used during anterior cervical spine surgery.\u003c/p\u003e \u003cp\u003eHowever, literature supporting the utilization of IONM has been mixed since introduction of the technology. Numerous independent studies and systematic reviews are inconclusive in its use as standard of care with no significant clinical differences reported[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. A recent Cochrane review from 2019 similarly reported finding no significant difference in the rates of RLNP between IONM and the visual identification group[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The consensus was that more high-quality, randomized control trials were needed before IONM can be designated as standard of care. On the contrary, multiple recent studies have shown the effectiveness of IONM including a 2017 meta-analysis of 34 original studies that found IONM to be effective in decreasing RLN injury during thyroidectomy[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. More recent, studies have also found significant differences supporting the use of IONM versus no IONM, in prevention of vocal cord palsy[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIONM of the RLN can be accomplished through visual interpretation of EMG recordings generated by an endotracheal tube that is appropriately positioned and in contact with bilateral vocal cords. At our institution where this protocol was developed, the NIM Trivantage\u003csup\u003e\u0026trade;\u003c/sup\u003e (Medtronic, Minneapolis, MN) EMG endotracheal tube (ETT) was utilized as the recording device. Electrodes are embedded within the ETT and it is positioned such that these electrodes remain in constant contact with the bilateral vocal cords throughout surgery until completion[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Correct placement of the tube, along with other recommendations such as avoidance of lubrication of the ETT, avoidance of topicalization of the vocal cords with local anesthetic (LTA), avoidance of the use of long acting neuromuscular blockers, and use of anticholinergic agents to dry secretions when excess saliva is observed during video laryngoscopy to avoid the salt bridging phenomenon, is paramount in increasing the accuracy of EMG monitoring and decreasing the incidence of alerts. Alerts as they pertain to RLN monitoring are failures to obtain an EMG response when a surgeon has identified or directly stimulated the RLN. False alerts increase the likelihood of clinically significant post-operative deficits.\u003c/p\u003e \u003cp\u003eStandardized practices and protocols are necessary to minimize inappropriate variations among the anesthesia care team, which can lead to decreased efficacy of IONM and ultimately patient injury. Randolph et al 2011, produced an international standards guideline that has set the framework for consistent IONM[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. In this novel project we developed and successfully implemented a protocol for correct placement of the specialized ETT. Implementation of this protocol led to higher quality and more reliable neuromonitoring during these procedures. We have maintained high levels of adherence to the protocol through systematic re-education at department meetings. As a result of the improved efficacy of ETT placement and quality of monitoring, we believe our project could be implemented at other institutions with ease.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThe standardized protocol for correct placement of the specialized ETT was designed using available literature, case reports, statements from different scientific societies and expert opinion. The protocol included step by step instructions for the preparation of equipment prior to placement of the ETT, considerations during placement and specific instructions for securing and verifying ETT placement. Pharmacologic and anesthetic recommendations and contraindications were also included (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The protocol was introduced to clinical practice in 2013\u0026ndash;2014. Multiple and recurrent educational strategies for training of anesthesia personnel were used to ensure all team members had proper training and access to the protocol. After the first round of education, the protocol was distributed electronically and physical copies were placed in all anesthetizing locations. In addition, all certified IONM technologists had a copy of the protocol available for easy consultation. Personalized training was provided to new team members.\u003c/p\u003e \u003cp\u003e Colorado Multiple Institutional Review Board (COMIRB) approval was obtained prior to the initiation of this study. The University of Colorado Hospital (UCH) electronic medical records systems (Centricity Anesthesia from 2009\u0026ndash;2010, EPIC from 2011\u0026ndash;2014) and the UCH intra-operative neuromonitoring database were queried to identify all surgical cases that would be appropriate for inclusion in this study.\u003c/p\u003e \u003cp\u003eInclusion criteria included surgeries of the neck (thyroidectomies, parathyroidectomies, and/or neck dissections) between January 2009 and December 2018, that required intra-operative monitoring of the RLN via free-running and stimulated EMG. EMG responses were continuously monitored and recorded by a certified IONM technologist and supervised by an attending neuroanesthesiologist.\u003c/p\u003e \u003cp\u003eA chi-square test of proportions was used to calculate the risk difference of the group prior to protocol implementation (combined 4 years: 2009,2010,2011,2012) and that of the groups after protocol implementation (combined years :2013 and 2014). SAS version 9.4 was used to analysis the results. A significance level of 0.05 was used. In order to determine the efficacy of the implemented protocol, a follow-up data analysis was performed. The follow up period was defined as the time after implementation of the standardized protocol (2015\u0026ndash;2018). During the follow-up period EPIC and the UCH intra-operative neuromonitoring database were queried. The same inclusion criteria were used.\u003c/p\u003e \u003cp\u003eIn summary, this retrospective study extracted data relating to the number of neck procedures requiring RLN monitoring, C-MAC use, and alerts prior to protocol implementation (2009 and 2012), immediately after implementation (2013\u0026ndash;2014), and after the protocol became standard of care (follow-up period 2015\u0026ndash;2018). The purpose was to evaluate if incorporation of the protocol as standard of care resulted in any significant changes since the initial introduction of the protocol in 2013 and 2014. Summaries are presented as count (percentage) or average percentage. A two-sample test of proportions was used to compare the 2013\u0026ndash;2014 and 2015\u0026ndash;2018 periods to detect any significant change in the rate of alerts. The analysis was completed using R v3.6.0 and the figure was created in Excel.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 607 patients underwent intra-operative RLN monitoring between January 2009 and December 2014. During this time, there was a 622% increase in the number of cases in which intra-operative RLN monitoring was utilized, from 27 cases in 2009 to 168 cases in 2014. The introduction of a standardized protocol for correct placement was implemented in 2013 and 2014. There was a significant association of the standardized protocol with reduced proportion of alerts. The overall proportion of alerts in the non-protocolized group was 7.5% (4%,11%). The overall proportion of alerts in the protocolized group was 2.1% (0.8%,5.7%). The risk difference was determined to be 5.36% (1.9%,8.8%).\u003c/p\u003e \u003cp\u003ePrior to the introduction of a standardized protocol there were alerts in 15% of cases in 2009 and 7.8% in 2012. After the implementation of the protocol and its establishment as standard of care, the rate of alerts decreased to 1.5-3% between 2013\u0026ndash;2018 (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Specifically, the overall proportion of alerts was 1.8% (6/327) in 2013\u0026ndash;2014 and 2.8% (30/1080) in 2015\u0026ndash;2018, which did not represent a significant change (increase of 1% [95% CI:-2.9\u0026ndash;1.0%], p\u0026thinsp;=\u0026thinsp;0.456).The use of C-MAC increased from 15% (4/27) in 2009 to 95% (89/94) by 2012. C-MAC use was 81% (264/327) between 2013\u0026ndash;2014 during the introduction of the protocol. After the implementation of the protocol as standard of care between 2015\u0026ndash;2018, the use of C-MAC was 97% (1048/1080) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eAccurate and precise placement of EMG ETTs is essential to provide reliable and consistent data to surgeons in real-time as they begin their approach to or dissect in direct approximation to the RLN. Surgeon complaints of variable or low positive predictive value (PPV) of IONM has hindered its broader utilization[1].\u0026nbsp;\u0026nbsp;With this study,\u0026nbsp;we attempted to minimize alerts by improving correct placement of EMG ETTs through direct visualization with video laryngoscopy and optimization of anesthesia technique.\u0026nbsp;\u0026nbsp;Despite significant increases in staffing numbers, provider turnover, and number of cases performed, absolute utilization of C-MAC\u003csup\u003e®\u003c/sup\u003e increased from 15% to 91% during the implementation period.\u0026nbsp;This was associated with a significant decrease in alerts during neck surgeries. This effect continued to be observed at our institution years after the implementation of this protocol as shown by a statistically insignificant difference in the percentage of alerts in the implementation and post implementation cohorts.\u0026nbsp;Interval education of anesthesia providers at large meetings of faculty (Grand Rounds, departmental meetings, etc) likely had an impact in reducing gradual decline in adherence to the protocol.\u0026nbsp;\u0026nbsp;At the same time, laminated, color-printed cards with detailed, photographic descriptions of the protocol were made available in all operating rooms in our facility. This reference material served as a reminder for those practitioners who didn’t regularly participate in the care of patients having neck surgery. The neuroanesthesia faculty served as a core group of experts in this protocol and continue to be available for troubleshooting and teaching. The neuromonitoring technologists at our institution were also involved in the implementation of this protocol and their buy-in increased project success.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIt is difficult to definitively identify which of the interventions explained above was responsible for the effects observed. As was previously stated in addition to the implementation of video laryngoscopy as the gold standard for placement of ETT in these cases several recommendations were made. That being said the focus of the protocol and the main focus of staff education was on the use of video laryngoscopy for appropriate placement of the ETT. One variable that we could not account for was practitioner choice of size of the EMG ETT, though recommendations were made in the protocol to adhere to a binary size system based on gender that recommended 7.0 mm ETT and 8.0mm ETT for female and male patients respectively. This variable was not controlled for and has the potential to affect the reliability of EMG monitoring for these cases if practitioners opted to downsize ETT due to diameter-tracheal mismatch. Other possible confounding variables include length of surgery, amount of patient secretions, equipment malfunction or failure and surgeon misidentification of neural tissue could account for the persistent rate of alerts. These factors are difficult to eliminate and would pose a challenge to study in isolation as they could potentially lead to patient harm. Future studies could be aimed at identifying whether this intervention can lead to improvement in the delivery of quality care, patient outcomes, reduction in clinical harm and increased trust and reliance on IONM.\u003c/p\u003e\n\u003cp\u003eDespite these limitations, given the reduction in alerts during the implementation period and the persistent low incidence of alerts in the post-implementation period, it is clear that protocolizing the placement of EMG ETT with compulsory verification using video laryngoscope as well anesthetic technique during head and neck surgery leads to a decrease in IONM alerts.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eConflicts of Interest:\u003c/strong\u003e None\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDetails of Prior presentation: \u003c/strong\u003ePresented at ASA 2019 as Oral Poster Presentation\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eApproval was obtained from Institutional Review Board (Colorado Multiple Institutional Review Board [COMIRB]) at the University of Colorado Denver, USA. The need for patient informed consent was waived or exempted by the Colorado Multiple Institutional Review Board [COMIRB]. All relevant methods were undertaken in strict accordance with departmental and institutional regulations.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data are available upon request. \u0026nbsp;Any request for additional information should be directed to the corresponding author.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors have no competing interests to disclose.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was conducted using Departmental funds.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eC.S. designed and led the study, analyzed the data and wrote the manuscript, J.M. wrote the manuscript and analyzed the data, L.E. wrote the manuscript and analyzed the data, S.C. analyzed the data and wrote the manuscript, A.K. analyzed the data and wrote the manuscript, L.J. analyzed the data and wrote the manuscript, A.O. analyzed the data and wrote the manuscript, C.C. designed and led the study, analyzed the data and wrote the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eDralle H, et al. Intraoperative monitoring of the recurrent laryngeal nerve in thyroid surgery. World J Surg. 2008;32(7):1358\u0026ndash;66.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSosa JA et al. \u003cem\u003eIncreases in thyroid nodule fine-needle aspirations, operations, and diagnoses of thyroid cancer in the United States.\u003c/em\u003e Surgery, 2013. 154(6): p.\u0026nbsp;1420-6; discussion 1426-7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang D, et al. Neural monitoring in thyroid surgery is here to stay. Gland Surg. 2020;9(Suppl 1):S43\u0026ndash;s46.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMalik R, Linos D. Intraoperative Neuromonitoring in Thyroid Surgery: A Systematic Review. World J Surg. 2016;40(8):2051\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePisanu A, et al. Systematic review with meta-analysis of studies comparing intraoperative neuromonitoring of recurrent laryngeal nerves versus visualization alone during thyroidectomy. J Surg Res. 2014;188(1):152\u0026ndash;61.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCirocchi R, et al. Intraoperative neuromonitoring versus visual nerve identification for prevention of recurrent laryngeal nerve injury in adults undergoing thyroid surgery. Cochrane Database Syst Rev. 2019;1:Cd012483.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBai B, Chen W. Protective Effects of Intraoperative Nerve Monitoring (IONM) for Recurrent Laryngeal Nerve Injury in Thyroidectomy: Meta-analysis. Sci Rep. 2018;8(1):7761.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWojtczak B, et al. Voice quality preservation in thyroid surgery with neuromonitoring. Endocrine. 2018;61(2):232\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKartal K et al. \u003cem\u003eIntraoperative Neuromonitoring in Thyroid Surgery: An Efficient Tool to Avoid Bilateral Vocal Cord Palsy\u003c/em\u003e. Ear Nose Throat J, 2020: p. 145561320906325.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJulien N, et al. Intraoperative laryngeal nerve monitoring during thyroidectomy and parathyroidectomy: A prospective study. Eur Ann Otorhinolaryngol Head Neck Dis. 2012;129(2):69\u0026ndash;76.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRandolph GW, et al. Electrophysiologic recurrent laryngeal nerve monitoring during thyroid and parathyroid surgery: international standards guideline statement. Laryngoscope. 2011;121(Suppl 1):S1\u0026ndash;16.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-3304342/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3304342/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground:\u003c/h2\u003e \u003cp\u003eRecurrent laryngeal nerve (RLN) injury during neck surgery can cause significant morbidity related to vocal cord (VC) dysfunction. VC electromyography (EMG) is used to aid in identification of the RLN and can reduce the probability of inadvertent surgical injury. Errors in placement of specialized EMG endotracheal tubes (ETT) can result in unreliable signals, false-negative responses, or no response when stimulating the RLN. We describe a novel educational protocol developed to optimize uniformity in placement of ETTs to improve reliability of RLN monitoring.\u003c/p\u003e\u003ch2\u003eMethods:\u003c/h2\u003e \u003cp\u003eIntraoperative neuromonitoring database was queried for all neck surgeries requiring RLN monitoring. Data points extracted for all cases requiring EMG monitoring for neck procedures. Free running and stimulated EMG were monitored and continuously recorded by a certified technologist. Alerts were compared between 2013-14 and 2015-18 using a two-sample test of proportions.\u003c/p\u003e\u003ch2\u003eResults:\u003c/h2\u003e \u003cp\u003eSignificant reductions in alerts were demonstrated after protocol implementation (7.5% pre-implementation to 2.1% post). Alerts were compared between 2013-14 (overall alert rate of 1.8%, pre-implementation period) and 2015-18 (overall alert rate of 2.8%, post-implementation period).\u003c/p\u003e\u003ch2\u003eConclusion:\u003c/h2\u003e \u003cp\u003eProtocolization for placement of EMG-ETT improved accuracy in EMG monitoring. In the follow-up cohort of 1,080 patients, use of this protocol continued to reduce the rate of alerts related to ETT malposition confirming the sustainability of this intervention through routine education. Risk of nerve injury is reduced when the rate of alerts is minimized. Scheduled or continuous protocol education of anesthesia personnel should continue to ensure compliance with protocol.\u003c/p\u003e","manuscriptTitle":"Implementation of a Standardized Protocol for Recurrent Laryngeal Nerve Monitoring Reduces False Negative Results during Neck Surgery: A Quality Control Case Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-09-18 16:16:16","doi":"10.21203/rs.3.rs-3304342/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"451ffdb1-9707-4f8d-8b41-695a63847921","owner":[],"postedDate":"September 18th, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-04-16T05:29:53+00:00","versionOfRecord":[],"versionCreatedAt":"2023-09-18 16:16:16","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3304342","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3304342","identity":"rs-3304342","version":["v1"]},"buildId":"FbvkV6FR0MCFSLy54lSbu","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}