Results Of 744 endotracheal intubations, 163 propensity score-matched pairs were generated (1-to-n matching: C-DL group, 163 vs. DL group, 428).
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For the propensity-matched groups, the overall first pass success rate was 69%, while those in the C-DL and DL groups were 79% and 65%, respectively. Overall, multiple attempts were required in 8% of patients, with 4% in the C-DL group and 9% in the DL group. The overall complication rate was 11%, with 4% in the C-DL group and 14% in the DL group. In multivariable analysis, the adjusted odds ratios of C-DL use for first pass success, multiple attempts, and complications were 2.05 (95% confidence interval CI 1.18–2.87, p. Citation: Hwang SY, Lee SU, Lee TR, Yoon H, Park JH, Cha WC, et al. (2018) Usefulness of C-MAC video laryngoscope in direct laryngoscopy training in the emergency department: A propensity score matching analysis.
PLoS ONE 13(12): e0208077. Editor: Mohamed R. El-Tahan, Imam Abdulrahman Bin Faisal University College of Medicine, SAUDI ARABIA Received: October 11, 2017; Accepted: November 12, 2018; Published: December 12, 2018 Copyright: © 2018 Hwang et al. This is an open access article distributed under the terms of the, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: All relevant data are within the paper. Funding: The authors received no specific funding for this work. Competing interests: The authors have declared that no competing interests exist. Introduction Endotracheal intubation (ETI) is an essential method for emergency medicine (EM) physicians to establish definitive airways in critically-ill patients. Historically, the direct laryngoscopy technique has been standard to facilitate ETI. Acquisition of this technique by trainees can be accomplished by on-the-job training under the supervision of an experienced physician. The major limitation of conventional teaching methods is that the supervisor and operator do not share identical views of the anatomy and therefore cannot offer or receive real-time feedback.
Recently, video laryngoscope (VL) has become very popular for airway management. Several studies supporting the use of VL for trainee education have been published –.
One of the most useful benefits of VL for teaching ETI is that the supervisor and operator can share identical views on the monitor, and the supervisor can therefore direct the operator to optimize the glottis view and verify tube placement through the vocal cords. Although the uses of VL have increased recently in the emergency department (ED), conventional direct laryngoscope (DL) remains the most commonly used device to aid ETI. Despite its importance, the skill is difficult to master, and the incidence of difficult and failed intubations is higher in the emergency setting compared to the operating room ,. EM physicians require structured training to establish competency in DL, but the safety of patients must not be compromised by training. One of the most important indicators of competence, first pass success (FPS), is associated with reduced complications because critically-ill ED patients poorly tolerate prolonged attempts at ETI –.
Efforts should be made to reduce the number of intubation attempts during ETI training. C-MAC Video Laryngoscope (Karl Storz Endoskope, Tuttlingen, Germany) use the same blades as Macintosh DL, with the video camera located near the distal tip of the blade. The C-MAC can be used either for conventional DL or as a VL. In this study, operators used C-MAC as a DL. The goal of this study was to evaluate the usefulness of C-MAC as a training tool for the direct laryngoscopy in the ED.
We hypothesized that this approach would facilitate direct laryngoscopy training while improving patient safety, as indicated by increased FPS rates, fewer instances of multiple attempts, and reduced ETI-related complications, such as esophageal intubation (EI), compared to the conventional training methods ,. Study design and setting This study was approved by the Samsung Medical Center Institutional Review Board (IRB), and the need for informed consent was waived because this was a retrospective study and no interventions were performed (IRB number, 2017-04-051). This study was a single-center, retrospective study performed in an ED from April 1, 2014 to October 30, 2016. The institution was a university-affiliated tertiary teaching hospital located in a metropolitan city with approximately 70,000 ED visits a year. This institution has an accredited 4-year EM residency program. About 400 ETIs are performed per year among adult patients in the ED.
Most of the intubations are performed by EM physicians. In March 2014, a continuous quality-improvement program for emergency airway management was initiated. All ETI cases treated in the ED were registered for data collection and quality improvement activity in our institution’s airway management registry. Methods of measurement ETI cases were categorized into two groups according to the device used for the first attempt: 1) the DL group when a conventional DL was used; and 2) the C-DL group when a C-MAC was used as a DL with real-time feedback from the supervising physician. A conventional Macintosh blade (size 3 or 4) was used in the DL group, and a Macintosh-type C-MAC blade (size 3 or 4) was used in the C-DL group.
D-BLADE (Karl Storz Endoskope, Tuttlingen, Germany) was not used in this study because of its variation from conventional Macintosh blades. The C-MAC blade was connected to the accompanying C-MAC monitor to allow the supervisor to see the operator’s view during ETI. Operators were not allowed to see the monitor and were required to identify the anatomy through the patient’s mouth. The supervisor provided instructions in real time to assist the operator in finding the anatomical landmarks and verifying tube placement through the vocal cords.
The supervisor was not allowed to guide the hand of the trainee to assist ETI. If a critical situation was anticipated or occurred during the first attempt, the supervisor stopped the trainee and took over the blade or guided the hand of the trainee, which was recoded as second attempt. In the case of first attempt failure, the operator was allowed access to the screen or was allowed to select another available device. Stylet is an important issue affecting ETI success rates. Levitan et al. showed that a bending angle greater than 35° with a straight-to-cuff styletted tracheal tube impeded tube passage into the trachea.
We standardized the stylet use during the quality improvement program. Malleable steel stylets were used during ETI attempts in all cases in our ED. The tube was usually prepared as a straight-to-cuff shape with bend angles of approximately 30° just proximal to the cuff. The distal end of the stylet was positioned in the middle of the Murphy eye.
We stressed the importance of not letting the end of the stylet come out of the tube, which could result in injury the anterior tracheal wall. In the case of difficult ETIs, the operator modified the tube shape or bending angle based on his or her preference. All ETI procedures in our study were independently monitored by ED medical staff, and the data were collected in real time to minimize recall and reporting bias. Airway management registry was completed at the end of the procedure by the operator and monitoring staff, and the president of the quality improvement program confirmed these data. The following data were retrieved from the airway registry and from electronic medical records by a single abstractor: general characteristics of patients including age, sex, height and weight; indications for intubation; number of intubation attempts; intubating devices; glottic opening score as reported by the operator; presence of difficult airway characteristics; associated complications; operator experience with ETI; sedatives and neuromuscular blocking agents; and level of residency.
Intubation attempts were defined as the placement of a laryngoscope blade into the mouth regardless of successful tube insertion into the trachea. Multiple attempts were defined as three or more intubation attempts. FPS was defined as successful ETI on the first intubation attempt.
The term “junior resident” referred to first- and second-year residents, and “senior residents” referred to third- and fourth-year residents. Anticipated difficult airways were defined by the following characteristics: external appearance including short neck, facial trauma, or small mandible; obesity; Mallampati class 3 or higher; airway obstructions including airway edema or a history of tracheal stenosis; distorted airway due to tuberculosis or surgery; cervical immobilization; limited mouth opening less than 3 cm; and lung stiffness including pulmonary edema.
Post-intubation hypotension was defined as systolic blood pressure less than 90 mmHg at any time during the 30 minutes following intubation. Post-intubation hypoxemia was defined as peripheral oxygen saturation less than 80% at any time during the 30 minutes following intubation.
Cardiac arrest and preexisting hypotension were excluded from definitions of post-intubation hypotension or hypoxemia. Primary data analysis We present data as mean (standard deviation) for numeric data and number with percentage for categorical data. We used propensity score matching to adjust for patient and operator imbalance between the C-DL group and DL group using variables of indications for intubation, presence of difficult airway characteristics, level of residency (junior vs. Senior), and intubation experience of the operator (≤10 times vs. 10 times) ,. We used 1-to-n matching with caliper = 0.2.
The weighted generalized estimating equations approach was used to evaluate the relationships between C-DL and primary and secondary outcomes in both univariable analysis and multivariable analysis. For multivariable analysis, we selected covariates that showed differences with p values. Results A total of 939 ETI were performed during the study period.
Of these, 195 ETI were excluded, and the remaining 744 ETIs were included in final analysis. Of the eligible patients, 163 used C-DL, and the other 581 patients served as the controls.
Among these patients, 163 propensity score-matched pairs were generated (1-to-n matching: C-DL group, 163 vs. DL group, 428). The baseline characteristics of all patients and matched patients according to propensity score are shown in. The propensity score matching method resulted in balanced groups for matching variables.
Outcomes The primary and secondary outcomes are shown in. Before matching, the overall FPS rate of eligible patients was 72% (n = 539/744). For the propensity-matched groups, the overall FPS rate was 69% (n = 409/591), with 79% (n = 129/163) in the C-DL group and 65% (n = 280/428) in the DL group. Overall multiple attempts occurred in 8% (n = 44/591) of patients, 4% (n = 6/163) in the C-DL group and 9% (n = 38/428) in the DL group. The overall intubation-related complication rate was 11% (n = 65/591), with 4% (n = 7/163) in the C-DL group and 14% (n = 58/428) in the DL group.
The immediately-recognized EI rate was only 2% (n = 3/163) in the C-DL group but was 8% (n = 35/428) in the DL group. There were no unrecognized EIs in either group during the study period. Associations between C-DL and outcomes The results of univariable and multivariable analyses for primary and secondary outcomes in the propensity-matched 591 patients are shown in. The unadjusted odds ratios (OR) of C-DL for FPS rate, multiple attempts, and complications were 2.03 (95% CI 1.28–3.22; p. Discussion In this study, we evaluated the usefulness of C-MAC in direct laryngoscopy training in the ED. When baseline characteristics including indications of intubation, the presence of difficult airway characteristics, level of residency, and the intubation experience of the operator were adjusted by propensity score, the FPS rate was 79% in the C-DL group and 65% in the DL group.
In addition, multiple attempts and complication rates were lower in the C-DL group compared to the DL group. In multivariable analysis, C-MAC used as a DL was associated with increased FPS, fewer instances of multiple attempts, and lower complication rates, both before and after adjustment for additional confounding factors. Therefore, our findings have clinically important implications. Not only can this approach provide direct laryngoscopy training for residents, but it can also improve patient safety, as previous studies have shown that the number of intubation attempts is associated with the incidence of adverse events during emergent ETI –. Since VL was first introduced as an alternative device for ETI, several studies have demonstrated the advantages of VL over DL.
VL use is associated with better glottis exposure, less risk of EI, and a higher FPS rate, particularly in difficult airways ,–. It can also be used as a rescue method with a high success rate after a failed DL attempt ,. In terms of educational aspects, studies also have proven the usefulness of VL. VL allows all team members in the field to observe the intubation procedure through the screen. In this way, the experienced physician can show the trainee how to intubate, as well as direct the trainee during their intubation attempts.
Focusing on VL use as a direct laryngoscopy trainer, however, the studies were limited to operating rooms, and it has not been clearly established in the ED. Howard-Quijano et al.
conducted a prospective crossover study including 37 novices to determine whether video-assisted laryngoscopy improved the effectiveness of ETI training in patients under anesthesia. The trainees were not allowed access to the screen, and the intubation procedure was guided by a supervisor’s feedback, including hand positioning and anatomic landmarks. They showed that the success rate of ETI attempts was 69% during video-assisted instruction, with a 55% success rate during non-video-assisted instruction (P = 0.04).
EI occurred in 3% of video-assisted intubations and in 17% of conventional intubations (P. References. 1. Brown CA 3rd, Bair AE, Pallin DJ, Walls RM. Techniques, success, and adverse events of emergency department adult intubations.
Ann Emerg Med. 2015; 65:363–70.e1. Pmid:25533140. 2.
Howard-Quijano KJ, Huang YM, Matevosian R, Kaplan MB, Steadman RH. Video-assisted instruction improves the success rate for tracheal intubation by novices. Br J Anaesth. 2008; 101:568–72. Pmid:18676418.
3. Low D, Healy D, Rasburn N. The use of the BERCI DCI Video Laryngoscope for teaching novices direct laryngoscopy and tracheal intubation.
2008; 63:195–201. Pmid:18211452.
4. You JS, Park S, Chung SP, Park YS, Park JW. The usefulness of the GlideScope video laryngoscope in the education of conventional tracheal intubation for the novice. 2009; 26:109–11.
Pmid:19164620. 5. Martin LD, Mhyre JM, Shanks AM, Tremper KK, Kheterpal S. 3,423 emergency tracheal intubations at a university hospital: airway outcomes and complications.
2011; 114:42–8. Pmid:21150574. 6. Sakles JC, Mosier J, Patanwala AE, Dicken J. Learning curves for direct laryngoscopy and GlideScope(R) video laryngoscopy in an emergency medicine residency.
West J Emerg Med. 2014; 15:930–7. Pmid:25493156. 7.
Emergency tracheal intubation: complications associated with repeated laryngoscopic attempts. Anesth Analg. 2004; 99:607–13, table of contents. Pmid:15271750.
8. Sakles JC, Chiu S, Mosier J, Walker C, Stolz U. The Importance of First Pass Success When Performing Orotracheal Intubation in the Emergency Department. Academic Emergency Medicine.
2013; 20:71–8. Pmid:23574475. 9. Hasegawa K, Shigemitsu K, Hagiwara Y, Chiba T, Watase H, Brown CA 3rd, et al. Association between repeated intubation attempts and adverse events in emergency departments: an analysis of a multicenter prospective observational study.
Ann Emerg Med. 2012; 60:749–54.e2. Pmid:22542734. 10. Sakles JC, Mosier JM, Patanwala AE, Arcaris B, Dicken JM. The Utility of the C-MAC as a Direct Laryngoscope for Intubation in the Emergency Department. 2016; 51:349–57.
Pmid:27471132. 11. Sakles JC, Javedani PP, Chase E, Garst-Orozco J, Guillen-Rodriguez JM, Stolz U. The use of a video laryngoscope by emergency medicine residents is associated with a reduction in esophageal intubations in the emergency department. Acad Emerg Med.
2015; 22:700–7. Pmid:25996773. 12. Weiss M, Schwarz U, Dillier CM, Gerber AC.
Teaching and supervising tracheal intubation in paediatric patients using videolaryngoscopy. Paediatr Anaesth. 2001; 11:343–8. Pmid:11359595. 13. Levitan RM, Pisaturo JT, Kinkle WC, Butler K, Everett WW.
Stylet bend angles and tracheal tube passage using a straight-to-cuff shape. Acad Emerg Med. 2006; 13:1255–8.
Pmid:17079788. 14.
Fogg T, Annesley N, Hitos K, Vassiliadis J. Prospective observational study of the practice of endotracheal intubation in the emergency department of a tertiary hospital in Sydney, Australia.
Emerg Med Australas. 2012; 24:617–24. Pmid:23216722.
15. Vassiliadis J, Tzannes A, Hitos K, Brimble J, Fogg T. Comparison of the C-MAC video laryngoscope with direct Macintosh laryngoscopy in the emergency department. Emerg Med Australas.
2015; 27:119–25. Pmid:25640845. 16. Brown CA 3rd, Bair AE, Pallin DJ, Laurin EG, Walls RM. Improved glottic exposure with the Video Macintosh Laryngoscope in adult emergency department tracheal intubations.
Ann Emerg Med. 2010; 56:83–8. Pmid:20202720.
17. Sakles JC, Mosier J, Chiu S, Cosentino M, Kalin L.
A comparison of the C-MAC video laryngoscope to the Macintosh direct laryngoscope for intubation in the emergency department. Ann Emerg Med. 2012; 60:739–48. Pmid:22560464. 18. Sakles JC, Patanwala AE, Mosier JM, Dicken JM.
Comparison of video laryngoscopy to direct laryngoscopy for intubation of patients with difficult airway characteristics in the emergency department. Intern Emerg Med.
2014; 9:93–8. Pmid:24002788. 19. Sakles JC, Mosier JM, Patanwala AE, Dicken JM, Kalin L, Javedani PP. The C-MAC(R) video laryngoscope is superior to the direct laryngoscope for the rescue of failed first-attempt intubations in the emergency department. 2015; 48:280–6.
Pmid:25498851. 20.
Emergency Handling Plan
Aziz MF, Brambrink AM, Healy DW, Willett AW, Shanks A, Tremper T, et al. Success of Intubation Rescue Techniques after Failed Direct Laryngoscopy in Adults: A Retrospective Comparative Analysis from the Multicenter Perioperative Outcomes Group. 2016; 125:656–66.
Pmid:27483124. 21. Kleine-Brueggeney M, Greif R, Schoettker P, Savoldelli GL, Nabecker S, Theiler LG. Evaluation of six videolaryngoscopes in 720 patients with a simulated difficult airway: a multicentre randomized controlled trial.
Br J Anaesth. 2016; 116:670–9. Pmid:27106971.
22. Sgalambro F, Sorbello M. Videolaryngoscopy and the search for the Holy Grail. Br J Anaesth. 2017; 118:471–2. Pmid:28203746.
Editor, We appreciate the interest of Liu et al. In our publication. We would like to comment on the questions raised in their letter. First, all three anaesthetists were properly trained in both techniques (C-MAC videolaryngoscope and direct laryngoscopy, University Hospital Zurich, Zurich, Switzerland) prior to the start of this study. Of course, all three had much greater experience with direct laryngoscopy (average about 1000 intubations) compared with C-MAC (between 30 and 300 intubations), but their level of training was sufficient. The sufficient level of training was confirmed by the finding of our study that the success rate at the first intubation attempt was 100 and 98%, respectively. Second, we basically agree that switching the intubation technique from video to direct laryngoscopy might be an important advantage of several videolaryngoscopes.
However, this was neither investigated, nor indicated, in any intubation attempt to achieve successful intubation in our study. Although the clinical assessment of Liu et al. May be right, scientific evidence for their conclusion is incomplete. Third, at our institution, a stylet is mandatorily used for all rapid sequence intubation procedures. Therefore, all (endotracheal tubes) in both groups were prepared with a hockey-stick shaped stylet in advance. Fourth, we agree with Liu et al. That a cut-off time might be important in some airway studies.
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However, in the clinical and especially the emergency setting, clinical judgement and decision-making is more important than any definition of timeframe. In general, the rate of successful endotracheal intubation and avoidance of unrecognised oesophageal intubation are clinically of the highest importance.
In contrast, the clinical impact of time to intubation is questionable as a difference of a couple of seconds is usually of no clinical relevance. Finally, the well tolerated use of the videolaryngoscope is completely supported by the data of our study and we, therefore, basically agree that the use of the videolaryngoscope might be an acceptable first-line intubation device. However, any recommendation for the first-line device during emergency airway management should be based on the provider's experience and the availability of the device.