Jump to comment:

• Identification of technical factors associated with first-pass success of intubation with C-MAC video laryngoscope in children
  Tian Tian, Bin Hu and Fu-Shan Xue
  Published on: 5 May 2021

• Published on: 5 May 2021

  Identification of technical factors associated with first-pass success of intubation with C-MAC video laryngoscope in children

  • Tian Tian, Anesthetist Department of Anesthesiology, Beijing Friendship Hospital, Capital Medical University, Beijing, People's Republic of China.
  • Other Contributors:
    • Bin Hu, Anesthetist
    • Fu-Shan Xue, Professor

  To the Editor
  We have read with great interest the recent article of Miller et al1 determining the technical factors associated with first-pass success (FPS) during endotracheal intubation with C-MAC video laryngoscope (VL) in children. They showed that placement of the blade tip into the epiglottic vallecula regardless of blade types, adequate glottic view and locating the glottic opening within second quintile of video displayer were significantly associated with FPS. Given that paediatric airway management is a great challenge to emergency physicians and the benefits of videolaryngoscopy are often significant in airway management of emergency paediatric patients,2 their findings have potentially clinical implications. Other than limitations described by authors in discussion, however, we noted several methodological issues in their article on which we invited authors to comment.
  First, primary outcome of this study was FPS, which was defined as passage of C-MAC VL into the mouth with the intention of intubation that terminated with successful intubation at first attempt. As described by authors in introduction, however, C-MAC VL is an intubating device with ability to perform both direct and video laryngoscopy using same device. That is, the larynx can be seen either under direct vision or on a monitor when using C-MAC VL.3 This advantage of C-MAC VL makes it exceptionally useful for emergency intubation. For example, in the event of a failed video laryngosc...

  Show More

  To the Editor
  We have read with great interest the recent article of Miller et al1 determining the technical factors associated with first-pass success (FPS) during endotracheal intubation with C-MAC video laryngoscope (VL) in children. They showed that placement of the blade tip into the epiglottic vallecula regardless of blade types, adequate glottic view and locating the glottic opening within second quintile of video displayer were significantly associated with FPS. Given that paediatric airway management is a great challenge to emergency physicians and the benefits of videolaryngoscopy are often significant in airway management of emergency paediatric patients,2 their findings have potentially clinical implications. Other than limitations described by authors in discussion, however, we noted several methodological issues in their article on which we invited authors to comment.
  First, primary outcome of this study was FPS, which was defined as passage of C-MAC VL into the mouth with the intention of intubation that terminated with successful intubation at first attempt. As described by authors in introduction, however, C-MAC VL is an intubating device with ability to perform both direct and video laryngoscopy using same device. That is, the larynx can be seen either under direct vision or on a monitor when using C-MAC VL.3 This advantage of C-MAC VL makes it exceptionally useful for emergency intubation. For example, in the event of a failed video laryngoscopy attempt, intubators can immediately switch direct laryngoscopy to continuously perform intubation procedure without the need to remove device from the mouth for a second attempt, and vice versa.4 In fact, available evidence indicates that common reasons for failed first attempt with C-MAC VL are the fogging of the lens, bloods and secretions on the camera, poor glottic view and video dysfunction (screen failure or inability to start the video function), rather than technical factors.3 As the authors did not provide the causes of failed first attempt with C-MAC VL, it was unclear whether all of the failed first attempts should be attributable to technical factors.
  Second, types of initial laryngoscopists, such as resident, fellow and attending physicians, were used for assessment on the competence level of intubators with C-MAC VL in this study. These may not be good proxies for the level of competence with an intubating device, as the competence with an intubating tool is mainly dependent on number of successful use.5 The recent work of Amalric et al6 in showed that the operators' expertise, which is assessed by number of previous video laryngoscopies performed, is an independent determinant of FPS with McGrath MAC video laryngoscope in critically ill patients.
  Third, the method of building multivariable model to determine clinical variables associated with FPS was questioned. In fact, the data provided by authors in table 2 are the results of initial comparisons on demographics and intubation characteristics between patients with and without FPS, rather than the results of univariate analysis for demographics and intubation data, which include P values and unadjusted odds ratios with their 95% confidence intervals. According to general principles of establishing a multivariable model, only the variables with statistical significance (P<0.05) in the initial comparison can be incorporated into the univariable model to examine multicollinearity among candidate variables. Furthermore, only the variables with large P values (P<0.2) in the univariate analysis can be entered into the multivariable model for statistical adjustment. By such adjustment of patients’ baseline characteristics and controlling of selection biases, the independent factors associated with FPS can be identified. Furthermore, independent contribution of each significant factor to FPF can also be assessed by its adjusted odds ratios and 95% CI.7 Because of this statistical question, we are concerned that the inference of multivariable analysis to determine clinical variables associated with FPS would have been distorted.
  Finally, the appropriateness of multivariable model to determine clinical variables associated with FPS was not assessed by the Hosmer-Lemeshow goodness-of-fit test. Furthermore, the c-index of multivariable model was not calculated. Thus, it cannot determine whether the multivariable model established in this study has a good fit and an adequate discriminative performance.7
  Contributors
  TT suggested comments and drafted the manuscript. BH revised the comments and the manuscript. FSX critically revised the comments and wrote the manuscript. All authors have read and approved the final manuscript.
  Funding
  The authors have not declared a specific grant for this work from any funding agency in the public, commercial or not-for-profit sectors.
  Competing interests
  None declared.
  Patient and public involvement
  Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this work.
  Patient consent for publication
  Not required.
  REFERENCES
  1. Miller KA, Monuteaux MC, Nagler J. Technical factors associated with first-pass success during endotracheal intubation in children: analysis of videolaryngoscopy recordings. Emerg Med J. 2020 Nov 10: doi: 10.1136/emermed-2020-209700.
  2. Miller KA, Nagler J. Advances in Emergent Airway Management in Pediatrics. Emerg Med Clin North Am. 2019; 37:473-91.
  3. Xue FS, Li HX, Liu YY, et al. Current evidence for the use of C-MAC videolaryngoscope in adult airway management: a review of the literature. Ther Clin Risk Manag 2017; 13:831-41.
  4. Sakles JC, Mosier JM, Patanwala AE, et al. The Utility of the C-MAC as a Direct Laryngoscope for Intubation in the Emergency Department. J Emerg Med 2016; 51:349-57.
  5. Crewdson K, Lockey D, Voelckel W, et al. Best practice advice on pre-hospital emergency anaesthesia & advanced airway management. Scand J Trauma Resusc Emerg Med 2019; 27:6.
  6. Amalric M, Larcher R, Brunot V, et al. Impact of Videolaryngoscopy Expertise on First-Attempt Intubation Success in Critically Ill Patients. Crit Care Med. 2020; 48(10):e889-e96.
  7. Vittinghoff E, McCulloch CE. Relaxing the rule of ten events per variable in logistic and Cox regression. Am J Epidemiol 2007; 165:710-8.

  Show Less

  Conflict of Interest:
  None declared.

  • Back to top