| Campagne et al., 2008 | Prospective OS | ED | 280 (63/210) | Adults | GVL | Unclear | Unknown | Unclear |
| De Jong et al., 2013 | Prospective before–after OS | ICU | 210 (140/70) | Adults | McGrath MAC | Most are inexperienced | No | Most RSI |
| Driver et al., 2016 | RCT | ED | 198 (103/95) | Adults | C-MAC | Most experienced | No | Most RSI |
| Driver et al., 2018 | OS | ED | 823 (428/395) | Adults | C-MAC | Inexperienced | Unclear | Most RSI |
| Gao et al., 2018 | RCT | ICU | 163 (81/82) | Adults | UEscope | Experienced | No | Sedatives without any NMBA |
| Goksu et al., 2016 | RCT | ED | 150 (75/75) | Age ≥ 16 years | C-MAC | Most inexperienced (ED residents and attending physicians) | No | All used RSI except patients with cardiac arrest. |
| Griesdale et al., 2012 | RCT | ICU | 40 (20/20) | Age ≥ 16 years without cardiac arrest. Patients with cervical spine precautions, anticipated difficult intubation, oxygen saturation < 90%, or systolic blood pressure < 80 mmHg despite resuscitation were excluded. | GVL | Inexperienced | Yes | All RSI |
| Hypes et al., 2016 | OS | ICU | 809 (673/136) | Nasotracheal intubations, flexible fiberoptic bronchoscopy or supraglottic devices, and intubations performed by medical students or attending physicians were excluded. | GVL, C-MAC, KingVision, and McGrath MAC | Inexperienced | No | Most RSI |
| Janz et al., 2016 | RCT | ICU | 150 (74/76) | Adult | McGrath MAC and GVL | Inexperienced | No | All used sedatives and most used NMBAs |
| Khandelwal et al., 2014 | Retrospective | In-hospital, out-of-OR | 420 (49/371) | Adult | GVL | Most experienced | No | Unclear |
| Kim et al., 2016 | RCT | ED | 140 (71/69) | Adult patients with CPR | GVL | Experienced | No | None |
| Kory et al., 2013 | Retrospective | ICU and medical or surgical wards | 138 (78/50) | Not mentioned | GVL | Inexperienced operators | No | NMBAs were not used routinely. |
| Lakticova et al., 2015 | OS | ICU | 392 (252/140) | Not mentioned | GVL | Relatively inexperienced | No | Graded intravenous sedation without NMBAs |
| Lascarrou et al., 2017 | RCT | ICU | 371 (186/185) | Adult patients without CPR | MaGrath Mac | Most inexperienced | No | All RSI |
| Lee et al., 2014 | Retrospective | General wards | 229 (121/108) | Patients in general wards with acute deterioration in clinical status or requiring CPR | GVL or AirwayScope | Inexperienced (50.2%) and experienced (49.8%) | Unclear | Probably none |
| Noppens et al., 2012 | Prospective, before-after study | Anesthetist-lead surgical ICU | 230 (117/113) | Adult | C-MAC | Most experienced | No | All used RSI except patients with cardiac arrest. |
| Okamoto et al., 2018 | Multicentre, prospective, OS | ED | 3360 (613/2747) | Adult patients with cardiac arrest | C-MAC,McGrath, AirwayScope, and GVL | Most inexperienced | No | Probably none |
| Park et al., 2015 | Historically controlled clinical design | ED | 83 (49/34) | All adults out-of-hospital cardiac arrest patients requiring emergency tracheal intubation during CPR in the ED | GVL | Inexperienced | Unclear | Probably none |
| Sakles et al., 2015 | Retrospective | ED | 3425 (1895/1530) | All patients in whom intubation attempts were made in the ED by EM residents with a DL or VL. | GVL or C-MAC | Inexperienced | No | Most RSI |
| Silverberg et al., 2015 | quasi-RCT | ICU | 117 (57/60) | Patients with a known history of difficult intubation, presence of limited mouth opening, oropharyngeal masses, or swollen tongue, or oxygen saturation less than 92% after bag valve mask ventilation were excluded. | GVL | Inexperienced | Yes | Sedatives were chosen as needed, but NMBA was not used. |
| Sulser et al., 2016 | RCT | ED | 147 (74/73) | Adult patients without CPR | C-MAC | Experienced | No | As needed |
| Vassiliadis et al., 2015 | Retrospective | ED | 619 (353/266) | ED patients | C-MAC | Most inexperienced | No | Most RSI |
| Yeatts et al., 2013 | RCT | ED | 623 (303/320) | CPR patients were excluded. | GVL | Experienced | No | All RSI |
