Effectiveness of preoxygenation strategies: a systematic review and network meta-analysis.

BACKGROUND: Preoxygenation is universally recommended before induction of general anaesthesia to prolong safe apnoea time. The optimal technique for preoxygenation is unclear. We conducted a systematic review to determine the preoxygenation technique associated with the greatest effectiveness in adult patients having general anaesthesia. METHODS: We searched six databases for randomised controlled trials of patients aged ≥16 yr, receiving general anaesthesia in any setting and comparing different preoxygenation techniques and methods. Our primary effectiveness outcome was safe apnoea time, and secondary outcomes included incidence of arterial oxygen desaturation; lowest SpO2 during airway management; time to end-tidal oxygen concentration of 90%; and [Formula: see text] and [Formula: see text] at the end of preoxygenation. We assessed the quality of evidence according to Grading of Recommendations, Assessment, Development and Evaluation (GRADE) recommendations. RESULTS: We included 52 studies of 3914 patients. High-flow nasal oxygen with patients in a head-up position was most likely to be associated with a prolonged safe apnoea time when compared with other strategies, with a mean difference (95% credible interval) of 291 (138-456) s and 203 (79-343) s compared with preoxygenation with a facemask in the supine and head-up positions, respectively. Subgroup analysis of studies without apnoeic oxygenation also showed high-flow nasal oxygen in the head-up position as the highest ranked technique, with a statistically significantly delayed mean difference (95% credible interval) safe apnoea time compared with facemask in supine and head-up positions of 222 (63-378) s and 139 (15-262) s, respectively. High-flow nasal oxygen was also the highest ranked technique for increased [Formula: see text] at the end of preoxygenation. However, the incidence of arterial desaturation was less likely to occur when a facemask with pressure support was used compared with other techniques, and [Formula: see text] was most likely to be lowest when preoxygenation took place with patients deep breathing in a supine position. CONCLUSIONS: Preoxygenation of adults before induction of general anaesthesia was most effective in terms of safe apnoea time when performed with high-flow nasal oxygen with patients in the head-up position in comparison with facemask alone. Also, high-flow nasal oxygen in the head-up position is likely to be the most effective technique to prolong safe apnoea time among those evaluated. Clinicians should consider this technique and patient position in routine practice. SYSTEMATIC REVIEW PROTOCOL: PROSPERO CRD42022326046.

Videolaryngoscopes versus direct laryngoscopes in children: Ranking systematic review with network meta-analyses of randomized clinical trials.

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.