Table 2.
Baseline characteristics of the included studies
| Study ID | Groups (interventions/exposures) | No. of participants | Age mean (SD) | Sex (male) n (%) |
BMI mean (SD) | Indication for intubation n (%) |
||||
|---|---|---|---|---|---|---|---|---|---|---|
| Pulmonary | Trauma | Neurologic | Fluid overload, cardiac/renal | Other | ||||||
| Ahmadi (2014) [18] | Direct-L | 49 | 49.1 (12.5) | 35 (73) | 23.82 (5.21) | - | - | - | - | - |
| Video-L | 48 | 52.3 (14.1) | 29 (59.2) | 22.1 (4.72) | - | - | - | - | - | |
| Ajith (2022) [19] | Direct-L | 38 | - | - | - | - | - | - | - | - |
| Video-L | 38 | - | - | - | - | - | - | - | - | |
| Arima (2014) [20] | Direct-L | 56 | 74.1 (13) | 38 (71.7) | - | - | - | - | - | - |
| Video-L | 53 | 74.4 (13.6) | 34 (60.7) | - | - | - | - | - | - | |
| Driver (2016) [21] | Direct-L | 95 | 52.6 (17.1) | 62 (60) | - | 66 (64) | 10 (10) | - | 4 (4) | 13 (13) |
| Video-L | 103 | 51.6 (18.8) | 63 (66) | - | 52 (55) | 16 (17) | - | 5 (5) | 8 (8) | |
| Goksu (2016) [22] | Direct-L | 75 | 39 (19) | 70 (93.3) | 25.3 (4.53) | 14 (19) | 33 (44) | 4 (5.3) | 11 (14.7) | - |
| Video-L | 75 | 35 (15.5) | 73 (97.3) | 24 (3.02) | 13 (17.3) | 25 (33.3) | 5 (6.7) | 16 (21.3) | - | |
| Ilbagi (2021) [23] | Direct-L | 35 | 45.7 (11.3) | 20 (57.1) | - | - | - | - | - | - |
| Video-L | 35 | 45.3 (11.2) | 16 (45.7) | - | - | - | - | - | - | |
| Kim (2016) [24] | Direct-L | 69 | 60.5 (18.7) | 49 (71.0) | - | - | - | - | - | - |
| Video-L | 71 | 61.3 (18.5) | 45 (63.4) | - | - | - | - | - | - | |
| Loughnan (2019) [25] | Direct-L | 49 | 52.3 (17.56) | 30 (61) | 28.3 (5.9) | - | - | - | - | - |
| Video-L | 51 | 53.7 (20.6) | 25 (49) | 28.53 (5.2) | - | - | - | - | - | |
| Macke (2020) [26] | Direct-L | 76 |
Median (Q: Q3) 68 (55:78) |
113 (74.3) | - | 2 (2.6) | 27 (48.7) | 5 (6.6) | 41 (53.9) | 4 (5.2) |
| Video-L | 76 | - | 2 (2.6) | 24 (31.6) | 6 (7.9) | 29 (38.2) | 2 (2.6) | |||
| Noppens (2012) [27] | Direct-L | 140 | 62.9 (15.6) | 87 (64.9) | 26.9 (7.6) | 83 (59.3) | - | 8 (5.7) | 3 (2.1) | 33 (23.6) |
| Video-L | 134 | 63.8 (16.7) | 86 (64.2) | 26.7 (6.4) | 86 (64.2) | - | 9 (6.7) | 2 (1.5 | 31 (23.1) | |
| Sanguanwit (2021) [28] | Direct-L | 80 | 65 (17.2) | 40 (50) | - | - | - | - | - | - |
| Video-L | 78 | 73 (12.9) | 44 (57) | - | - | - | - | - | - | |
| Sulser (2016) [29] | Direct-L | 73 | 55 (80.1) | - | - | - | - | - | - | - |
| Video-L | 74 | 68 (87.7) | - | - | - | - | - | - | - | |
| Sun (2020) [30] | Direct-L | 88 | 49.4 (9.7) | 34 (38.60 | 23.6 (5.7) | - | - | - | - | - |
| Video-L | 88 | 49.3 (7.8) | 39 (44) | 23.7 (2.75) | - | - | - | - | - | |
| Yeatts (2013) [31] | Direct-L | 303 | 43 (12.6) | 244 (76.3) | - | 14 (4.4) | - | 12 (3.8) | - | - |
| Video-L | 320 | 42 (16.83) | 216 (71.3) | - | 10 (3.3) | - | 6 (2.0) | - | - | |