Summary of findings 1. High levels of PEEP compared to low levels of PEEP for patients with acute lung injury and acute respiratory distress syndrome.
| High levels of PEEP compared to low levels of PEEP for patients with acute lung injury and acute respiratory distress syndrome | ||||||
| Patient or population: patients with acute lung injury and acute respiratory distress syndrome Setting: mechanical ventilation in critical care Intervention: high levels of PEEP Comparison: low levels of PEEP | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | №. of participants (studies) | Certainty of evidence (GRADE) | Comments | |
| Risk with low levels of PEEP | Risk with high levels of PEEP | |||||
| Mortality before hospital discharge | Study population | RR 0.97 (0.90 to 1.04) | 3640 (7 RCTs) | ⊕⊕⊕⊝ MODERATEb | ||
| 427 per 1000 | 414 per 1000 (384 to 444) | |||||
| Moderatea | ||||||
| 590 per 1000 | 572 per 1000 (531 to 614) | |||||
| Oxygen efficiency (PaO₂/FIO₂) Day 1 | Mean PaO₂/FIO₂ ranged from 124 to 168 in included studies | MD 51 (36 higher to 66 higher) | ‐ | 2594 (6 RCTs) | ⊕⊕⊝⊝ LOWb,c | |
| Oxygen efficiency (PaO₂/FIO₂) Day 3 | Mean PaO₂/FIO₂ ranged from 134 to 175 in included studies | MD 50 (35 higher to 66 higher) | ‐ | 2309 (6 RCTs) | ⊕⊕⊝⊝ LOWb,d | |
| Oxygen efficiency (PaO₂/FIO₂) Day 7 | Mean PaO₂/FIO₂ ranged from 168 to 184 in included studies | MD 29 (21 higher to 36 higher) | ‐ | 1611 (5 RCTs) | ⊕⊕⊕⊝ MODERATEb | |
| Barotrauma | Study population | RR 1.00 (0.64 to 1.57) | 3791 (9 RCTs) | ⊕⊕⊝⊝ LOWb,f | ||
| 69 per 1000 | 69 per 1000 (44 to 109) | |||||
| Lowe | ||||||
| 16 per 1000 | 16 per 1000 (10 to 25) | |||||
| Ventilator‐free days until Day 28 (only studies reporting means) | Mean days ranged from 6 to 15 in included studies | MD 0.5 (2.0 lower to 2.9 higher) | ‐ | 1654 (3 RCTs) | ⊕⊕⊝⊝ LOWa,g | |
| *The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; FIO₂: fraction of inspired oxygen; MD: mean difference; PaO₂: partial pressure of oxygen; PEEP: positive end‐expiratory pressure; RCT: randomised controlled trial; RR: risk ratio. | ||||||
| GRADE Working Group grades of evidence. High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect. | ||||||
aMortality rate taken from the control arm of the largest study (Cavalcanti 2017). Hospital mortality rate is 40% (Bellani 2016).
bDowngraded one level due to indirectness of evidence. There is clinical heterogeneity because patients in included studies differ in their level of disease severity (assessed through oxygenation).
cDowngraded one level due to serious concerns about study limitations. Minimal overlap among studies; P value for heterogeneity was < 0.00001 and I² was 85%.
dDowngraded one level due to serious concerns about inconsistency. Minimal overlap among studies; P value for heterogeneity was < 0.0001 and I² was 83%.
eBarotrauma rate taken from the control arm of the largest study (Cavalcanti 2017). Barotrauma rate is 13% (Eisner 2002).
fDowngraded one level due to serious concerns about inconsistency. Minimal overlap among studies. P value for heterogeneity was < 0.009 and I² was 63%.
gDowngraded one level due to serious concerns about inconsistency. Minimal overlap among studies. P value for heterogeneity was < 0.005 and I² was 81%.