Video laryngoscopy versus direct laryngoscopy for orotracheal intubation in the out-of-hospital environment: a systematic review and meta-analysis

Objective: To determine the effect of video and direct laryngoscopy on first-pass success rates for out-of-hospital orotracheal intubation. Methods: MEDLINE, Embase, and Cochrane databases were searched from inception to January 2023. Out-of-hospital studies comparing video and direct laryngoscopy on either first-pass or overall intubation success were included. A random effects meta-analysis was performed with a primary outcome of first-pass success stratified by clinician type and laryngoscope blade geometry. The secondary outcomes were overall intubation success stratified by clinician type, and intubation time. All hypotheses and subgroup analyses were determined a priori. Results: Twenty-five studies involving 35,489 intubations met inclusion criteria. Substantial heterogeneity (>75%) precluded reporting point estimates for nearly all analyses. For our primary outcome, video laryngoscopy was associated with improved first-pass success in 3/5 physician studies, 4/6 critical care paramedic/registered nurse studies, and 7/10 paramedic studies. Video laryngoscope devices with Macintosh blade geometry were associated with improved first-pass success in 7/10 studies, while devices with hyperangulated geometry were associated with improved first-pass success in 3/7 studies. Overall intubation success was greater with video laryngoscopy in 2/6 studies in the physician subgroup and 9/10 studies in the paramedic subgroup. Video laryngoscopy was not associated with overall intubation success among critical care paramedics/nurses (OR = 1.89, 0.96 to 3.72, I2 = 34%). Lastly, 4/5 studies found video laryngoscopy to be associated with longer intubation times. Conclusions: We found substantial heterogeneity among out-of-hospital studies comparing video laryngoscopy to direct laryngoscopy on first-pass success, overall success, or intubation time. This heterogeneity was not explained with stratification by study design, clinician type, video laryngoscope blade geometry, or leave-one-out meta-analysis. A majority of studies showed that video laryngoscopy was associated with improved first pass success in all subgroups, but only for paramedics and not physicians when looking at overall success. This improvement was more common in studies that used Macintosh blades than those that used hyperangulated blades. Future research should explore the heterogeneity identified in our analysis with an emphasis on differences in training, clinical milieu, and specific video laryngoscope devices.

研究目的：明确视频喉镜（video laryngoscopy）与直接喉镜（direct laryngoscopy）对院外经口气管插管（out-of-hospital orotracheal intubation）首次尝试成功率（first-pass success）的影响。
研究方法：检索MEDLINE、Embase及Cochrane数据库自建库至2023年1月的相关文献。纳入对比视频喉镜与直接喉镜用于院外环境下首次尝试或整体插管成功率的研究。采用随机效应模型开展Meta分析，主要结局指标为按操作者类型及喉镜镜片几何构型分层的首次尝试插管成功率；次要结局指标为按操作者类型分层的整体插管成功率，以及插管耗时。所有研究假设及亚组分析均于研究前期预先设定（a priori）。
研究结果：共有25项符合纳入标准的研究，涉及35489例插管病例。各项分析的异质性均较高（I²>75%），因此几乎无法报告合并效应量点估计值。针对主要结局指标，在5项医师相关研究中，有3项显示视频喉镜可提升首次尝试插管成功率；在6项重症监护急救医师/注册护士相关研究中，有4项观察到该优势；在10项院前急救医师相关研究中，有7项显示该优势。采用Macintosh镜片构型（Macintosh blade geometry）的视频喉镜设备，在10项研究中有7项显示可提升首次尝试插管成功率；而采用高角度几何构型（hyperangulated geometry）的设备，在7项研究中有3项显示该优势。整体插管成功率方面，在医师亚组的6项研究中，有2项显示视频喉镜更具优势；在院前急救医师亚组的10项研究中，有9项观察到该优势。在重症监护急救医师/护士亚组中，视频喉镜未显著提升整体插管成功率（比值比OR=1.89，95%置信区间0.96~3.72，I²=34%）。最后，在5项研究中有4项显示视频喉镜的插管耗时更长。
研究结论：本研究发现，在对比视频喉镜与直接喉镜用于院外经口气管插管的首次尝试成功率、整体插管成功率或插管耗时的相关研究中，存在显著异质性。该异质性无法通过研究设计、操作者类型、视频喉镜镜片构型或逐一剔除式Meta分析（留一法Meta分析）来解释。多数研究显示，视频喉镜可提升各亚组的首次尝试插管成功率，但在整体插管成功率层面，仅在院前急救医师亚组观察到该优势，医师亚组未显示出显著优势。且采用Macintosh镜片的研究中，该优势较采用高角度镜片者更为常见。未来研究应针对本分析中发现的异质性展开探索，重点关注操作者培训背景、临床环境及特定视频喉镜设备的差异。