Archives of Academic Emergency Medicine. 2020; 8(1): 81 OR I G I N A L RE S E A RC H Success Rate of Endotracheal Intubation Using Inline Sta- bilization with and without Cervical Hard Collar; a Com- parative Study Welawat Tienpratarn1, Chaiyaporn Yuksen1, Kasamon Aramvanitch1, Karn Suttapanit1, Yahya Mankong1, Nussareen Yaemluksanalert1, Sansanee Meesawad1∗ 1. Department of Emergency Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand. Received: August 2020; Accepted: September 2020; Published online: 10 October 2020 Abstract: Introduction: Application of a rigid cervical collar may interfere with the laryngeal view, and potentially lead to failed endotracheal intubation (ETI). This study aimed to compare intubation success rates while performing inline stabilization with and without cervical hard collar. Methods: This randomized prospective comparative study included paramedics working in the Department of Emergency Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand to compare the success rates of endotracheal intubation on manikin using inline stabilization with and without cervical hard collar. Results: 125 participants were evaluated; 63 in the rigid cervi- cal collar and 62 in the non-cervical hard collar group. The rate of successful intubation was significantly higher using manual stabilization without cervical hard collar (61 (96.8%) vs. 55 (88.7%); p=0.048). The time required to successfully perform intubation was also shorter, with manual stabilization only (14.1 ±20.9 vs. 18.9±29.0; p = 0.081). Conclusion: It seems that, removal of the rigid cervical collar during ETI in patients with suspected traumatic spine injury could increase the intubation success rate. Keywords: Intubation, Intratracheal; Spinal Injuries; Multiple trauma; Restraint, Physical Cite this article as: Tienpratarn W, Yuksen Ch, Aramvanitch K, Suttapanit K, Mankong Y, Yaemluksanalert N, Meesawad S. Success Rate of Endotracheal Intubation Using Inline Stabilization with and without Cervical Hard Collar; a Comparative Study. Arch Acad Emerg Med. 2020; 8(1): e81. 1. Introduction Traumatic Spinal Injury (TSI) is one of the most common life- threatening traumatic conditions. It can injure nearby or- gans, such as the spinal cord, which can cause severe com- plications ranging from minor injuries to disability or death (1). There is an average incidence of 10.5 spinal injuries per 100,000 people worldwide or approximately 768,473 in- cidents per year. The most common cause is traffic acci- dents followed by falls; about 48.8% of spinal injuries require surgery (2). In patients with suspected TSI, transportation requires a rigid cervical collar, head immobilization device, and spinal sup- port throughout the lifting and moving procedure (3). In pa- ∗Corresponding Author: Chaiyaporn Yuksen; Department of Emergency Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, 270 Rama VI Road, Thung Phaya Thai, Ratchathewi, Bangkok, Thailand, 10400. E-mail: chaipool0634@hotmail.com, Tel: (+66)8-3183-1373, Fax: (+66)-2201- 2404 tients with a threatened airway, essential preliminary treat- ments are required for preventing airway obstruction and providing adequate ventilation support (1). In TSI patients, tracheal intubation must be performed carefully to prevent further injury to the cervical spine and spinal cord (4). More- over, manual inline stabilization using a rigid cervical collar is recommended to reduce the movement of the cervical spine during tracheal intubation (5). Using a rigid cervical collar and performing manual inline stabilization in patients suspected to have a cervical TSI can reduce the intubation-related movement of the cervical spine and aggravation of TSI (6). But the application of a rigid cervical collar can cause difficulty in airway management, decrease the inter-incisor, increase the Mallampati classifica- tion, decrease the angles of neck extension, and reduce cer- vical spine movements (7). Removing the rigid cervical col- lar or anterior portion during tracheal intubation has been suggested by an expert physician. Manual inline stabiliza- tion is a maneuver in which the care provider is standing at the patient’s head, using the palms of both hands to grip the This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem W. Tienpratarn et al. 2 sides of the patients’ head, which is reportedly a safe tech- nique to perform during intubation. Using a rigid cervical collar and performing manual inline stabilization in patients suspected to have a cervical TSI can reduce the intubation- related movement of the cervical spine (8). However, no reports have clearly described intubation suc- cess rates while using a rigid cervical collar and whether it is necessary to remove the rigid cervical collar during intuba- tion. This study aimed to compare intubation success while using a rigid cervical collar along with manual inline stabi- lization versus manual inline stabilization alone when per- formed by paramedics on a manikin. 2. Methods 2.1. Study design and setting This randomized prospective comparative study included paramedics working at the Department of Emergency Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand to compare the success rate of endotra- cheal intubation on manikin using inline stabilization with and without cervical hard collar. This study was approved by the institutional Ethics Committee Board of Ramathibodi Hospital Faculty of Medicine, Mahidol University. The Ethics Approval Reference Number is MURA2018/900. 2.2. Participants Eligible paramedic students who provided a signed consent to participate in the research were included and those who refused to participate were excluded. Participants were ran- domly assigned to endotracheal intubation using inline sta- bilization either with rigid cervical collar or without it us- ing sequentially numbered opaque sealed envelopes and six- block randomization. Participants in the rigid cervical collar group performed intubation with a rigid cervical collar and manual inline stabilization and others performed intubation using manual inline stabilization without a rigid cervical col- lar (figure 1). 2.3. Definitions and procedures The data recorded in this study included the success of in- tubation within 60 seconds. Successful intubation was de- fined as the endotracheal tube’s insertion into the manikin’s bronchus in a maximum of two attempts. The successful intubation time was defined as the period from passing the equipment through the axial plane of manikin’s front teeth to successful intubation. The viewpoint of intubation was de- fined as the viewpoint of the larynx during intubation, based on Mallampati classification. The manikin was not moved, nor was the rigid collar re- moved. The rigid cervical collar position was measured each time intubation was conducted to ensure it was in the same position. Only one set of equipment, comprising of a Mac- intosh laryngoscope and No. 3 blades, was used in the study. Only one No. 7 endotracheal tube was used in the study. The equipment was tested for readiness before each intubation procedure, and the manikin was fixed in the original location and position. The duration of the study was two months, and we used the same manikin and equipment. 2.4. Data gathering The researcher recorded demographic variables of partici- pants, intubation success, time to the success of intubation, and the laryngeal view grade for each participant, using a predesigned checklist. 2.5. Statistical Analysis For sample size estimation, we used the data from a pilot study of 20 paramedics intubating a manikin. The pilot study was done in Ramathibodi Hospital. The rate of intubation success within 60s in groups with and without collar was 92% and 70%, respectively. With a 95% confidence interval and power of 80%, the sample size ratio 1:1, and p = 0.05, the two- sided test found that the minimum sample size should be 58 subjects. Chi-square and Fisher’s exact tests were used to compare the categorical data. McNemar’s test and t-test of rank-sum tests were used for the comparison of continuous data. All statisti- cal analyses were performed using Stata software version 14 (StataCorp, College Station, TX, USA). P < 0.05 was consid- ered statistically significant. 3. Results 125 participants were evaluated; 63 in the rigid cervical col- lar and 62 in the non-cervical hard collar group. Table 1 compares the baseline characteristics of participants. There were no statistically significant differences between groups regarding age (p =0.925), sex (p = 0.864), weight (p = 0.889), height (p = 0.985), and intubation experience (p = 0.878). The success of intubation was significantly higher with only manual inline stabilization compared to using the rigid cer- vical collar and manual inline stabilization (61 (96.8%) vs. 55 (88.7%); p = 0.048). The intubation time was shorter with only manual inline stabilization (14.1 ±20.9 vs. 18.9±29.0; p = 0.081). Comparison between the intubation characteristics of the 2 groups is presented in table 2. 4. Discussion The results showed that the overall rate of successful intuba- tion was significantly higher when using manual inline stabi- lization alone. Additionally, the laryngeal view grade was not significantly different between the two groups. In every trauma patient with suspected TSI, the cervical spine This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem 3 Archives of Academic Emergency Medicine. 2020; 8(1): 81 Figure 1: Endotracheal intubation using inline stabilization with and without rigid cervical collar on manikin. Table 1: Comparing the baseline characteristics of participants between groups Variables Intubation groups P values Inline (n = 63) Inline + Collar (n = 62) Age (year) Mean ± SD 23.5±5.1 23.2±4.2 0.925 Gender n (%) Male 32 (50.8) 31 (50.0) 0.864 Female 31(49.2) 31 (50.0) Weight (kg) Mean ± SD 63.9 ± 16.1 64.5 ± 9.5 0.889 Height (m) Mean ± SD 166.7 ± 8.0 166.4 ± 18.7 0.985 Intubation experience (year) Pre-clinical year paramedics 45 (71.4) 44 (71.0) 0.878 Clinical year paramedics 18 (28.6) 18 (29.0) Data are presented as mean ± standard deviation (SD) or number (%). Table 2: Comparing the intubation characteristics between groups Variables Intubation groups P Inline (n = 63) Inline + Collar (n = 62) Successful intubation Number (%) 61 (96.8) 55 (88.7) 0.048 Time to successful intubation (second) Mean ± SD 14.1 ±20.9 18.9±29.0 0.081 Attempts of successful intubations N (%) 1 52 (82.5) 50 (80.6) 2 9 (14.3) 5 (8.1) 0.098 ≥3 (failed) 2 (3.2) 7 (11.3) Laryngeal view grade* N (%) 1 19 (30.1) 14 (22.6) 2 32 (50.8) 32 (51.6) 0.675 3 11 (17.5) 15 (24.2) 4 1 (1.6) 1 (1.6) Time to first successful intubation (second) Mean ± SD 17.4 ± 14.4 18.8 ± 11.7 0.592 *Based on Mallampati classification. should be manually maintained in a neutral position before the primary survey and resuscitation. Applying a rigid cer- vical collar, stabilizing the body to a spinal board, and ad- equate external immobilization of the head should be per- formed. En route to the trauma center or emergency depart- ment (ED), if the TSI patients need assisted ventilation or en- This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem W. Tienpratarn et al. 4 dotracheal tube intubation, cervical collar might better be re- moved. On the scene or en route, ETI should be successful in a short period to prevent hypoxia and aspiration. It seems beneficial to remove the rigid cervical collar during ETI be- cause it increases the success rate and shortens intubation time. On scene or en route ETI is more difficult than ED intubation and a video laryngoscope, which improves laryngeal views, may not be available in prehospital care. Emergency medical service providers could remove the cervical collar and only apply manual inline stabilization before ETI for improving la- ryngeal views. One study that evaluated intubation of patients using the rigid cervical collar and manual inline stabilization showed that both methods could stabilize the cervical spine. How- ever, using rigid cervical collar, intubation success rate was reduced, and the laryngeal view was impaired. In addition, the applied methods were shown to significantly increase the time of intubation (9). Another study found that using a rigid cervical collar could reduce the movement of the spine, but performing ETI was significantly more difficult (7). The study by Kleine-Brueggeney M. et al. shows that the rigid cervical collar can cause limitations in mouth opening and significantly increase intubation time (10). The study by Yuk M. et al. was performed on 76 healthy volunteers in a sim- ulation study and showed that the LEMON criteria (mouth opening, modified Mallampati classification, and neck ex- tension) worsened significantly after rigid cervical collar ap- plication (7). The study by Yuksen C et al., comparing the efficiency of intu- bation between a video laryngoscope and Macintosh laryn- goscope on a manikin with a hard collar that restricted neck movement, showed that intubation success was significantly lower when using the Macintosh laryngoscope compared to when a video laryngoscope was used in the group of person- nel who had experience performing intubation. In the inex- perienced group, however, the time to successful intubation was not different between the two methods (11). This study was done including senior paramedic students whose endo- tracheal intubation skill was similar to paramedic physicians. The results of this study may be used in the practice of ETI to remove the rigid cervical collar, especially in a prehospital setting with time limitation. 5. Limitations There are some limitations to this study. First, the results of this study may not apply to real clinical situations as they were found using a manikin; but they may be used as pre- liminary data for further research. Second, using a manikin might have caused bias in evaluating the mallampati score, which should be further investigated by assessing the partic- ipant’s laryngeal view report. Deterioration of the equipment such as an endotracheal tube, guidewire, and energy of bat- tery of Macintosh laryngoscope might have caused bias and confounded our study results. 6. Conclusion It seems that, removal of the rigid cervical collar during ETI in patients with suspected TSI could increase the intubation success rate. 7. Declarations 7.1. Acknowledgements We thank Angela Morben, DVM, ELS, from Edanz Group (www.edanzediting.com/ac), for editing a draft of this manuscript. 7.2. Conflict of interest statement None of the authors have any conflicts of interest to disclose. 7.3. Source of funding The publication funding support by Ramathibodi hospital, Mahidol university. 7.4. Data availability statement The data are not available for public access because of par- ticipants privacy concern but are available from the corre- sponding author upon reasonable request. 7.5. Authors’ contribution All authors met the criteria for gaining authorship based on the recommendations of the International Committee of Medical Journal Editors. References 1. Xiong C, Hanafy S, Chan V, Hu ZJ, Sutton M, Escobar M, et al. Comorbidity in adults with traumatic brain injury and all-cause mortality: a systematic review. BMJ open. 2019;9(11). 2. Kumar R, Lim J, Mekary RA, Rattani A, Dewan MC, Sharif SY, et al. Traumatic spinal injury: global epi- demiology and worldwide volume. World neurosurgery. 2018;113:e345-e63. 3. Kreinest M, Gliwitzky B, Schuler S, Grutzner PA, MÃijnzberg M. Development of a new Emergency Medicine Spinal Immobilization Protocol for trauma pa- tients and a test of applicability by German emergency care providers. Scandinavian journal of trauma, resusci- tation and emergency medicine. 2016;24(1):1-10. This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem 5 Archives of Academic Emergency Medicine. 2020; 8(1): 81 4. Liao S, Popp E, Huttlin P, Weilbacher F, Munzberg M, Schneider N, et al. Cadaveric study of movement in the unstable upper cervical spine during emergency management: tracheal intubation and cervical spine immobilisation–a study protocol for a prospective ran- domised crossover trial. BMJ open. 2017;7(8):e015307. 5. Chan W-H, Cheng C-P, Chiu Y-L, Hsu Y-C, Hu M-H, Huang G-S. Two head positions for orotracheal intuba- tion with the trachway videolight intubating stylet with manual in-line stabilization: A randomized controlled trial. Medicine. 2020;99(17):e19645. 6. Liao S, Schneider NR, HÃijttlin P, GrÃijtzner PA, Weil- bacher F, Matschke S, et al. Motion and dural sac com- pression in the upper cervical spine during the applica- tion of a cervical collar in case of unstable craniocervical junction–A study in two new cadaveric trauma models. PloS one. 2018;13(4):e0195215. 7. Yuk M, Yeo W, Lee K, Ko J, Park T. Cervical collar makes difficult airway: a simulation study using the LEMON criteria. Clinical and experimental emergency medicine. 2018;5(1):22. 8. Oh H, Kim H, Yoon H-K, Lee H-C, Park H-P. No radio- graphic index predicts difficult intubation using the Op- tiscopeâĎć in cervical spine surgery patients: a retro- spective study. BMC anesthesiology. 2020;20(1):1-10. 9. Kim JW, Lee KR, Hong DY, Baek KJ, Lee YH, Park SO. Efficacy of various types of laryngoscope (direct, Pen- tax Airway Scope and GlideScope) for endotracheal in- tubation in various cervical immobilisation scenarios: a randomised cross-over simulation study. BMJ open. 2016;6(10):e011089. 10. Kleine-Bruggeney M, Greif R, Schoettker P, Savoldelli GL, Nabecker S, Theiler L. Evaluation of six videolaryngo- scopes in 720 patients with a simulated difficult airway: a multicentre randomized controlled trial. BJA: British Journal of Anaesthesia. 2016;116(5):670-9. 11. Yuksen C, Prachanukool T, Chinsupaluk W, Trainarongsakul T. Videolaryngoscope versus Macintosh Laryngoscope in Stimulated Patients With Limitation of Neck Movements. Ramathibodi Medical Journal. 2014;37(2):71-80. This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem Introduction Methods Results Discussion Limitations Conclusion Declarations References