Effectiveness of indirect versus direct laryngoscopes for nasotracheal intubation in adults undergoing elective surgery: a systematic review and network meta-analysis

It is not clear whether indirect laryngoscopes are superior to direct laryngoscopes for nasotracheal intubation and which laryngoscopes are better for nasotracheal intubation. We sought to undertake a ranking of the effectiveness of intubation devices in patients undergoing nasotracheal intubation. We conducted a systematic review and network meta-analysis (NMA). We searched electronic databases for prospective randomized studies comparing different tracheal intubation devices in patients undergoing nasotracheal intubation. The primary outcome was intubation time. The secondary outcomes were first-attempt success rate, glottic visualization, use of Magill forceps, and the use of external laryngeal manipulation. We used DerSimonian and Laird random-effects models for statistical analysis. We performed frequentist network meta-analysis and generated network plots and network league tables. We included 22 studies comparing 10 types of devices. With the Macintosh direct laryngoscope as reference, six indirect laryngoscopes significantly reduced intubation time relative to the Macintosh laryngoscope. In the ranking of intubation time, the C-MAC® D-Blade (Karl Storz SE & Co. KG, Tuttlingen, Germany) had the highest P-score (0.98), and the Macintosh blade had the lowest P-score (0.07). In terms of first-attempt success rate, the C-MAC D-Blade had the highest (P-score, 0.78) and the Airway Scope™ S100 (Nihon Koden, Tokyo, Japan) the lowest (P-score, 0.06). Regarding glottic visualization, the Truview EVO2 (Truphatek International, Netanya, Israel) achieved the highest P-score (0.79), while the McCoy laryngoscope (Penlon, Abingdon, UK) had the lowest P-score (0.05). In the present NMA to establish a ranking of the effectiveness of intubation devices in patients undergoing nasotracheal intubation, we found that most indirect laryngoscopes likely reduced intubation time, increased first-attempt success rates, and were more effective tracheal intubation devices for nasotracheal intubation compared with direct laryngoscopes The findings of the present a systematic review and NMA support a recommendation for the use of indirect laryngoscopes for nasotracheal intubation (very low certainty of evidence). PROSPERO ( CRD42023446646 ); first submitted 20 July 2023.