Table 3 GRADE assessments of certainty
Certainty assessment | â„– of patients | Effect | Certainty | Importance | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
â„– of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | V | C | Relative (95% CI) | Absolute (95% CI) | ||
Safe Apnea Time | ||||||||||||
 7 | randomized trials | not serious | not serious | not serious | not serious | none | 147 | 152 | - | MD 96.26 higher (29.41 higher to 163.12 higher) |
| Â |
Safe Apnea Time—Obese | ||||||||||||
 4 | randomized trials | not serious | not serious | not serious | not serious | none | 61 | 63 | - | MD 66.62 higher (2.73 higher to 130.51 higher) |
| Â |
Safe Apnea Time—Non-obese | ||||||||||||
 3 | randomized trials | not serious | not serious | not serious | seriousa | none | 86 | 89 | - | MD 125.38 higher (12.26 lower to 263.03 higher) |
| Â |
3 min PreOx FeO2 to 90% Number—Number to FeO2 90% after 3 min preoxygenation | ||||||||||||
 2 | randomized trials | not serious | not serious | not serious | not serious | strong association | 61/80 (76.3%) | 41/79 (51.9%) | OR 3.01 (1.52 to 5.96) | 246 more per 1,000 (from 102 to 346 more) |
| Â |
PaO2 (after PreOx) | ||||||||||||
 7 | randomized trials | not serious | seriousb | not serious | not serious | none | 123 | 127 | - | MD 5.43 higher (1.9 higher to 8.95 higher) |
| Â |
PaO2 (after PreOx)—Obese | ||||||||||||
 5 | randomized trials | not serious | seriousc | not serious | not serious | none | 87 | 87 | - | MD 4.98 higher (0.63 higher to 9.34 higher) |
| Â |
PaO2 (after PreOx)—Non-obese | ||||||||||||
 2 | randomized trials | not serious | seriousd | not serious | not serious | none | 36 | 40 | - | MD 6.51 higher (1.05 higher to 11.97 higher) |
| Â |
After PreOx vs After ETI—After preoxygenatiotion | ||||||||||||
 6 | randomized trials | not serious | not serious | not serious | not serious | none | 87 | 87 | - | MD 0.41 lower (0.58 lower to 0.23 lower) |
| Â |
After PreOx vs After ETI—After ETI | ||||||||||||
 2 | randomized trials | not serious | not serious | not serious | not serious | none | 44 | 44 | - | MD 0.28 lower (0.59 lower to 0.03 higher) |
| Â |
SpO2 after PreOx + PaO2 after ETI—PaO2 (after ETI) | ||||||||||||
 3 | randomized trials | not serious | seriouse | not serious | not serious | none | 64 | 64 | - | MD 4.42 higher (0.17 higher to 8.67 higher) |
| Â |
High
High
Moderate
High
Moderate
Moderate
Moderate
High
High
Moderate