Summary Videolaryngoscopes are thought to improve glottic view and facilitate tracheal intubation compared with the Macintosh direct laryngoscope. However, we currently do not know which one would be the best choice in most patients undergoing anaesthesia. We designed this systematic review with network meta‐analyses to rank the different videolaryngoscopes and the Macintosh direct laryngoscope. We conducted searches in PubMed and a further five databases on 11 January 2021. We included randomised clinical trials with patients aged ≥16 years, comparing different videolaryngoscopes, or videolaryngoscopes with the Macintosh direct laryngoscope for the outcomes: failed intubation; failed first intubation attempt; failed intubation within two attempts; difficult intubation; percentage of glottic opening seen; difficult laryngoscopy; and time needed for intubation. We assessed the quality of evidence according to GRADE recommendations and included 179 studies in the meta‐analyses. The C‐MAC and C‐MAC D‐Blade were top ranked for avoiding failed intubation, but we did not find statistically significant differences between any two distinct videolaryngoscopes for this outcome. Further, the C‐MAC D‐Blade performed significantly better than the C‐MAC Macintosh blade for difficult laryngoscopy. We found statistically significant differences between the laryngoscopes for time to intubation, but these differences were not considered clinically relevant. The evidence was judged as of low or very low quality overall. In conclusion, different videolaryngoscopes have differential intubation performance and some may be currently preferred among the available devices. Furthermore, videolaryngoscopes and the Macintosh direct laryngoscope may be considered clinically equivalent for the time taken for tracheal intubation. However, despite the rankings from our analyses, the current available evidence is not sufficient to ensure significant superiority of one device or a small set of them over the others for our intubation‐related outcomes.

We examined the potential for voice sounds to predict a difficult airway as compared with prediction by the modified Mallampati test. A total of 453 patients scheduled for elective surgery under general anaesthesia with tracheal intubation were studied. Five phonemes were recorded and their formants analysed. Difficult laryngoscopy was defined as the Cormack-Lehane grade 3 or 4. Univariate and multivariate logistic regression were used to examine the association between some variables (mouth opening, sternomental distance, modified Mallampati and formants) and difficult laryngoscopy. Difficult laryngoscopy was reported in 29/453 (6.4%) patients. Among five regression models evaluated, the model achieving better performance to predict difficult laryngoscopy, after a variable selection criteria (stepwise, multivariate) and included a modified Mallampati classification (OR 2.920; 95%CI 1.992-4.279; p < 0.001), first formant of /i/(iF1) (OR 1.003; 95%CI 1.002-1.04; p < 0.001), and second formant of /i/(iF2) (OR 0.998; 95%CI 0.997-0.998; p < 0.001). The receiver operating curve for a regression model that included both formants and Mallampati showed an area under curve of 0.918, higher than formants alone (area under curve 0.761) and modified Mallampati alone (area under curve 0.874). Voice presented a significant association with difficult laryngoscopy during general anaesthesia showing a 76.1% probability of correctly classifying a randomly selected patient.

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Background: Videolaryngoscopes improve tracheal intubation in adult patients, but we currently do not know whether they are similarly beneficial for children. We designed this ranking systematic review to compare individual video and direct laryngoscopes for efficacy and safety of orotracheal intubation in children. Methods:We searched PubMed and five other databases on January 27, 2021. We included randomized clinical trials with patients aged ≤18 years, comparing different laryngoscopes for the outcomes: failed first intubation attempt; failed intubation within two attempts; failed intubation; glottic view; time for intubation; complications. In addition, we assessed the quality of evidence according to GRADE recommendations. Results:We included 46 studies in the meta-analyses. Videolaryngoscopy reduced the risk of failed first intubation attempt (RR = 0.43; 95% CI: 0.31-0.61; p = .001) and failed intubation within two attempts (RR = 0.33; 95% CI: 0.33-0.33; p < .001) in children aged <1 year. Videolaryngoscopy also reduced the risk of major complications in both children aged <1 year (RR = 0.33; 95% CI: 0.12-0.96; p = .046) and children aged 0-18 years (RR = 0.40; 95% CI: 0.25-0.65; p = .002). We did not find significant difference between videolaryngoscopy and direct laryngoscopy for time to intubation in children aged <1 year (MD = −0.95 s; 95% CI: −5.45 to 3.57 s; p = .681), and children aged 0-18 years (MD = 1.65 s; 95% CI: −1.00 to 4.30 s; p = .222). Different videolaryngoscopes were associated with different performance metrics within this meta-analysis. The overall quality of the evidence ranged from low to very low. Conclusion:Videolaryngoscopes reduce the risk of failed first intubation attempts and major complications in children compared to direct laryngoscopes. However, not all videolaryngoscopes have the same performance metrics, and more data is needed to clarify which device may be better in different clinical scenarios. Additionally, care must be taken while interpreting our results and rankings due to the available evidence's low or very low quality.

Current evidence supports the benefit of videolaryngoscopy (VL) over direct laryngoscopy (DL) for many intubation outcomes in adult patients in a range of clinical scenarios [1,2]. However, VL may be performed using