There is compelling evidence to support the superiority of videolaryngoscopes over direct laryngoscopes for several adult tracheal intubation outcomes [1-3]. However, questions remain regarding this superiority in certain scenarios [4], including whether the results apply to experienced anaesthetists. We aimed to establish whether videolaryngoscopy increases the likelihood of a successful first tracheal intubation attempt and/or reduces the risk of oesophageal intubation and hypoxia when tracheal intubation is attempted by experienced anaesthetists, where high levels of competence with direct laryngoscopes might reduce the advantages of videolaryngoscopes.

This analysis was based on data from a systematic review, whose protocol was registered prospectively. We included randomised clinical trials that enrolled patients aged ≥ 16 y having elective surgery with tracheal intubation using either videolaryngoscopy or direct laryngoscopy performed by anaesthetists. Studies that involved anaesthesia trainees, anaesthesia associates and medical students were not included. Our primary outcome was rate of first attempt tracheal intubation success. We also assessed rates of oesophageal intubation and hypoxia. A trial sequential analysis was conducted to assess the risk of random error from subsequent meta-analyses for our main outcome.

In total, we included 120 studies comprising 12,954 patients. The overall risk of bias was generally categorised as either ‘some concerns’ or ‘high’, due primarily to outcome measurement or incomplete reporting (online Supporting Information Figure S1).

For tracheal intubation first-pass success, we included 117 studies evaluating 12,804 patients. There were varying levels of experience with devices across the studies. Videolaryngoscopy increased the likelihood of success during the first tracheal intubation attempt significantly (relative risk (95%CI) 1.05 (1.02–1.08), p < 0.001, Table 1). The rate of success during a first tracheal intubation attempt was estimated at 90.1% (95%CI 87.7–92.1%) with direct laryngoscopy and 95.3% (93.6–96.6%) with videolaryngoscopy. Further information can be found in the online Supporting Information Figure S2. Publication bias was assessed using the small sample bias approach (online Supporting Information Figure S3), and Egger's test showed a significant asymmetry (p < 0.001). The overall quality of evidence was judged low due to risk of publication bias and inconsistency. Trial sequential analysis indicated that the available data cannot exclude a type 1 error, and thus more information may still be required (Fig. 1).

For oesophageal intubation, we included 10 studies, with videolaryngoscopy reducing the risk of oesophageal intubation significantly (relative risk (95%CI) 0.33 (0.14–0.76), p = 0.015, Table 1). The quality of the evidence was considered moderate due to imprecision. For hypoxia, we included 10 studies. We did not detect significant differences between videolaryngoscopy and direct laryngoscopy for this outcome (Table 1), and the quality of evidence was low due to relevant imprecision.

Broadly, our results are consistent with available evidence supporting the superior rate of first-pass tracheal intubation success of videolaryngoscopy compared with direct laryngoscopy [1-3]. Even in scenarios where the value of videolaryngoscopy might be questioned, namely in the hands of experienced clinicians who are already skilled with direct laryngoscopy, these devices still showed a significant increase in the chance of first tracheal intubation attempt success.

It is important to note the significant variability in study results, highlighting the possibility that the superiority of videolaryngoscopy may not always hold true. Two characteristics that may partially explain this heterogeneity are the diverse types of devices used and the varying levels of expertise with video-assisted devices.

We must acknowledge the low certainty of the evidence which is due to publication bias and inconsistency. When viewed in isolation, this evidence may not seem robust enough to recommend the routine use of videolaryngoscopes by experienced anaesthetists. However, our results are in keeping with the overall trend, providing additional support for the superior efficacy of videolaryngoscopes over direct laryngoscopes. Therefore, it is reasonable to challenge the scepticism about whether videolaryngoscopy improves outcomes when used by experienced anaesthetists.

It is logical to assume that if an intervention can improve tracheal intubation efficacy, it would also reduce the risk of complications. As anticipated, our findings indicate that videolaryngoscopy significantly reduces the risk of oesophageal intubation compared with direct laryngoscopy. However, no significant difference was observed between the two interventions regarding incidence of hypoxia. This lack of statistically significant difference does not imply equivalence and may reflect lack of power in our analysis.

Collectively, the evidence supports the superiority of videolaryngoscopy in improving patient outcomes [1-3]. Even in scenarios where videolaryngoscopes might be deemed less valuable [4], our results still show enhanced efficacy and safety with an increased likelihood of successful first tracheal intubation attempts and a reduced risk of oesophageal intubation. As highlighted elsewhere [1, 5, 6], the focus might shift away from the specific operator towards identifying which video-assisted devices perform best in specific scenarios. However, we acknowledge that further studies are necessary.

In conclusion, videolaryngoscopy appears to improve tracheal intubation efficacy and safety in adult patients by increasing the chance of first-pass success and reducing the risk of oesophageal intubation during elective procedures performed by experienced anaesthetists, but with moderate or low certainty.

有令人信服的证据表明，在成人气管插管结局方面，视频喉镜优于直接喉镜[1-3]。然而，在某些情况下，关于这种优势仍然存在疑问 [4]，包括结果是否适用于有经验的麻醉师。我们旨在确定当经验丰富的麻醉师尝试气管插管时，视频喉镜检查是否会增加首次气管插管成功尝试的可能性和/或降低食管插管和缺氧的风险，其中直接喉镜的高水平能力可能会降低视频喉镜的优势。

该分析基于一项系统评价的数据，该评价的方案已被前瞻性注册。我们纳入了随机临床试验，这些试验招募了 ≥ 岁 16 岁的患者，这些患者使用视频喉镜或麻醉师进行的直接喉镜进行气管插管择期手术。涉及麻醉实习生、麻醉助理医师和医学生的研究未被纳入。我们的主要结局是首次尝试气管插管的成功率。我们还评估了食管插管和缺氧的发生率。进行试验序贯分析，以评估后续荟萃分析对我们主要结局的随机误差风险。

我们总共纳入了 120 项研究，涉及 12,954 名患者。总体偏倚风险通常被归类为“一些担忧”或“高”，主要是由于结局测量或报告不完整（在线支持信息图 S1）。

对于气管插管首过成功率，我们纳入了 117 项研究，评估了 12,804 名患者。不同研究中对设备的经验水平不同。视频喉镜检查显著增加了第一次气管插管尝试成功的可能性 （相对风险 （95%CI） 1.05 （1.02–1.08），p < 0.001，表 1）。直接喉镜检查首次气管插管尝试的成功率估计为 90.1% （95% CI 87.7-92.1%），视频喉镜检查成功率为 95.3% （93.6-96.6%）。更多信息可以在在线支持信息图 S2 中找到。使用小样本偏倚方法评估发表偏倚 （在线支持信息图 S3），Egger 检验显示显着不对称 （p < 0.001）。由于存在发表偏倚和不一致的风险，证据的总体质量被判定为低质量。试验序贯分析表明，现有数据不能排除 1 类错误，因此可能仍需要更多信息（图 1）。

对于食管插管，我们纳入了 10 项研究，视频喉镜检查显着降低了食管插管的风险 （相对风险 （95%CI） 0.33 （0.14-0.76），p = 0.015，表 1）。由于不精确性，证据质量被认为是中等的。对于缺氧，我们纳入了 10 项研究。我们没有发现视频喉镜检查和直接喉镜检查在该结局方面的显著差异（表1），并且由于相关的不精确性，证据质量低。

总体而言，我们的结果与现有证据一致，支持视频喉镜的气管插管首过成功率优于直接喉镜[1-3]。即使在视频喉镜检查的价值可能受到质疑的情况下，即在已经熟练使用直接喉镜检查的经验丰富的临床医生手中，这些设备仍然显示出首次气管插管尝试成功的机会显着增加。

重要的是要注意研究结果的显着差异，这突出了视频喉镜的优越性可能并不总是成立的可能性。可能部分解释这种异质性的两个特征是所使用的设备类型多样，以及视频辅助设备的专业知识水平不同。

我们必须承认，由于发表偏倚和不一致，证据质量低。当孤立地观察时，这些证据似乎不足以推荐有经验的麻醉师常规使用电子喉镜。然而，我们的结果与总体趋势一致，为电子喉镜优于直接喉镜的疗效提供了额外的支持。因此，对经验丰富的麻醉师使用视频喉镜检查是否能改善结局的怀疑提出质疑是合理的。

合乎逻辑地假设，如果干预措施可以提高气管插管效果，它也会降低并发症的风险。正如预期的那样，我们的研究结果表明，与直接喉镜相比，视频喉镜检查显着降低了食管插管的风险。然而，两种干预措施在缺氧发生率方面未观察到显著差异。这种缺乏统计学上显著的差异并不意味着等价，可能反映了我们分析中缺乏功效。

总的来说，证据支持视频喉镜在改善患者结局方面具有优势[1-3]。即使在视频喉镜可能被认为价值较低的情况下 [4]，我们的结果仍然显示疗效和安全性增强，首次气管插管尝试成功的可能性增加，食管插管的风险降低。正如其他地方 [1， 5， 6] 所强调的那样，重点可能会从特定操作员转移到确定哪些视频辅助设备在特定场景中表现最佳。但是，我们承认还需要进一步的研究。

总之，视频喉镜检查似乎通过增加首次通过成功的机会和降低由经验丰富的麻醉师进行的择期手术中食管插管的风险来提高成年患者的气管插管效果和安全性，但质量为中等或低。