Research letter
Videolaryngoscopy (VL) is increasingly being used in intensive care units (ICUs) and may increase the chance of first-pass success when intubation is difficult [1–3]. However, VL equipment may not always be available and direct laryngoscopy (DL) would then be required. While previous simulation studies demonstrated comparable retention of skills for DL versus VL in normal manikins [4, 5], it is unknown if VL training among physician trainees would lead to ineffective DL use for difficult intubation scenarios. We therefore aim to show if training using VL would lead to effective transfer of skills for difficult intubation using DL.
Ethical approval was sought from the National Healthcare Group Domain Specific Review Board (DSRB 2015/00937). Internal medicine (IM) residents who had little prior exposure to DL or VL were recruited and randomized into either DL (size 3 Macintosh blade) or VL (C-MAC®) training, using a normal airway manikin (Cormack-Lehane Grade I). For both groups, the intubation method and instructor remained the same. Residents were then assessed by two blinded assessors, using DL on a difficult airway manikin (Cormack-Lehane Grade III). The primary outcome was intubation time during the first attempt (after passing the laryngoscope between the lips), averaged between the two assessors. Intubation time was truncated at 120 s, beyond which the attempt was considered failed. The secondary outcome measures were first pass success rate and rate of complications from ETI (such as teeth damage and endobronchial intubation).
Forty-one residents were randomized (21 DL, 20 VL) (Table 1). The median intubation time taken for the DL and VL groups to intubate were 42.5 s (range 21–120 s) and 41.5 s (range 13–120 s), respectively, p = 0.273 (Table 2). Successful intubation on first attempt was recorded in 17 and 18 residents in the DL and VL group, respectively, p = 0.542. Between the DL and VL groups, complication rates were not significantly different: teeth damage (5 DL, 4 VL); endobronchial intubation (1 DL, 2 VL). With regards to inter-tester variability, the correlation between 1st and 2nd assessors for participants’ median time for intubation during the first attempt was excellent (Spearman’s rho = 0.992, p < 0.001).
Table 1.
Participant characteristics
| Characteristics | All participants (n = 41) | DL group (n = 21) | VL group (n = 20) | p value |
|---|---|---|---|---|
| Age (years) | 25.6 ± 2.8 | 25.0 ± 1.7 | 26.3 ± 3.6 | 0.123 |
| Female (%) | 19 (46.3) | 6 (28.6) | 13 (65.0) | 0.029 |
| PGY (%) | ||||
| 1 | 29 (70.7) | 15 (71.4) | 14 (70.0) | 0.561 |
| 2 | 6 (14.6) | 4 (19.1) | 2 (10.0) | |
| > 2 | 6 (14.6) | 2 (9.5) | 4 (20.0) | |
| Medical school (%) | ||||
| Local | 28 (68.3) | 14 (70.0) | 14 (66.7) | 1.000 |
| Foreign | 13 (31.7) | 6 (30.0) | 7 (33.3) | |
| Prior ED working experience (%) | 4 (9.8) | 2 (9.5) | 2 (10.0) | 1.000 |
| Prior ICU working experience (%) | 2 (4.9) | 1 (4.8) | 1 (5.0) | 1.000 |
| Prior number of successful intubations in live patients (%) | ||||
| 0 | 23 (56.1) | 10 (47.6) | 13 (65.0) | 0.688 |
| 1 | 9 (22.0) | 5 (23.8) | 4 (20.0) | |
| 2 | 1 (2.4) | 1 (4.8) | 0 | |
| > 2 | 8 (19.5) | 5 (23.8) | 3 (15.0) | |
| Prior intubation training (%) | 34 (82.9) | 18 (85.7) | 16 (80.0) | 0.697 |
DL direct laryngoscopy, ED emergency department, ICU intensive care unit, PGY postgraduate year, i.e., number of years after graduation from medical school, VL videolaryngoscopy
Table 2.
Intubation training results and complication rates
| Results | All participants (n = 41) | DL group (n = 21) | VL group (n = 20) | p value |
|---|---|---|---|---|
| Timing for 1st attempt (s)a | ||||
| Median | 42 | 42.5 | 41.5 | 0.273 |
| Interquartile range | 28–67 | 38–100 | 23–59 | |
| Range | 13–120 | 21–120 | 13–120 | |
| Number of failed attempts (%) | ||||
| 0 | 35 (85.4) | 17 (81.0) | 18 (90.0) | 0.542 |
| 1 | 4 (9.8) | 2 (9.5) | 2 (10.0) | |
| 2 | 2 (4.9) | 2 (9.5) | 0 | |
| Other complications (%) | ||||
| None | 29 (70.7) | 15 (71.4) | 14 (70.0) | 1.000 |
| Teeth damage | 9 (22.0) | 5 (23.8) | 4 (20.0) | |
| Endobronchial intubation | 3 (7.3) | 1 (4.8) | 2 (10.0) | |
aAverage timing recorded by 1st and 2nd assessors
DL, direct laryngoscopy, ED emergency department, ICU intensive care unit, PGY postgraduate year, i.e., number of years after graduation from medical school, VL videolaryngoscopy
In conclusion, training with VL, compared to DL, had similar transfer of skills for difficult intubation using DL. As our randomized trial was done under simulation conditions, further study within an authentic clinical environment would be needed to confirm our preliminary results.
Acknowledgements
Not applicable
Abbreviations
- DL
Direct laryngoscopy
- VL
Videolaryngoscopy
Authors’ contributions
AK and SKC conceived the study idea, wrote the protocol, obtained ethics approval, designed and carried out the study, and wrote the manuscript. RK contributed to the writing of the manuscript. RC, MD, and JT contributed to the training and assessment of the study participants. All authors read and approved the final manuscript.
Funding
The authors have not received funding for this study.
Availability of data and materials
The datasets generated and/or analyzed during the current study are not publicly available due as the local approval authority does not permit data sets to be placed publicly but are available from the corresponding author on reasonable request.
Ethics approval and consent to participate
We obtained ethics approval from National Healthcare Group Domain Specific Review Board (DSRB 2015/00937) and obtained a waiver of consent.
Consent for publication
Not applicable
Competing interests
The authors do not report any competing interests.
Footnotes
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Contributor Information
Adrian Kee, Email: Adrian_cl_kee@nuhs.edu.sg, Email: mdckcla@nus.edu.sg.
Reyor Ko, Email: reyor.ko@mohh.com.sg.
Rolando Capistrano, Email: rolandocapistrano@yahoo.com.
Melvin Dajac, Email: Melvin_dujac@nuhs.edu.sg.
Juvel Taculod, Email: juvel_taculod@nuhs.edu.sg.
Kay Choong See, Email: mdcskc@nus.edu.sg.
References
- 1.Hoshijima H, Denawa Y, Tominaga A, Nakamura C, Shiga T, Nagasaka H. Videolaryngoscope versus Macintosh laryngoscope for tracheal intubation in adults with obesity: a systematic review and meta-analysis. J Clin Anesth. 2017;44:69–75. doi: 10.1016/j.jclinane.2017.11.008. [DOI] [PubMed] [Google Scholar]
- 2.Lewis SR, Butler AR, Parker J, Cook TM, Smith AF. Videolaryngoscopy versus direct laryngoscopy for adult patients requiring tracheal intubation. Cochrane Database Syst Rev. 2016;11:CD011136. doi: 10.1002/14651858.CD011136.pub2. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Hypes CD, Stolz U, Sakles JC, Joshi RR, Natt B, Malo J, Bloom JW, Mosier JM. Video laryngoscopy improves odds of first-attempt success at intubation in the intensive care unit. A propensity-matched analysis. Ann Am Thorac Soc. 2016;13(3):382–390. doi: 10.1513/AnnalsATS.201508-505OC. [DOI] [PubMed] [Google Scholar]
- 4.Hunter I, Ramanathan V, Balasubramanian P, Evans DA, Hardman JG, McCahon RA. Retention of laryngoscopy skills in medical students: a randomised, cross-over study of the Macintosh, A.P. Advance() , C-MAC((R)) and Airtraq((R)) laryngoscopes. Anaesthesia. 2016;71(10):1191–1197. doi: 10.1111/anae.13589. [DOI] [PubMed] [Google Scholar]
- 5.Assaad MA, Lachance C, Moussa A. Learning neonatal intubation using the Videolaryngoscope: a randomized trial on mannequins. Simul Healthc. 2016;11(3):190–193. doi: 10.1097/SIH.0000000000000141. [DOI] [PubMed] [Google Scholar]
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Data Availability Statement
The datasets generated and/or analyzed during the current study are not publicly available due as the local approval authority does not permit data sets to be placed publicly but are available from the corresponding author on reasonable request.