Summary of findings for the main comparison. High‐frequency oscillation versus conventional ventilation for the treatment of acute respiratory distress syndrome.
| Patient or population: people with Acute Respiratory Distress Syndrome Settings: Critical Care Unit Intervention: High‐fFrequency oscillation Comparison: Conventional mechanical ventilation | ||||||
| Outcomes** | Illustrative comparative risks* (95% CI) | Relative effect (95% CI) | No of Participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| Conventional Mechanical Ventilation | High Frequency Oscillation | |||||
| Mortality (at 30 days or until hospital discharge) | Medium risk population1 | RR 0.92 (0.72 to 1.16) | 1779 (8 studies) | ⊕⊝⊝⊝ very low2,3,4,5,6 | ||
| 470 per 1000 | 432 per 1000 (338 to 545) | |||||
| Mortality (at 6 months) | Medium risk population | RR 0.79 (0.58 to 1.08) | 148 (1 study) | ⊕⊝⊝⊝ very low2,4,5 | ||
| 590 per 1000 | 466 per 1000 (342 to 637) | |||||
| Treatment failure | Medium risk population1 | RR 0.64 (0.48 to 0.85) | 956 (6 studies) | ⊕⊝⊝⊝ very low2,4,5,7 | ||
| 190 per 1000 | 122 per 1000 (91 to 162) | |||||
| Duration of mechanical ventilation days. Scale from: 14 to 22 | The mean duration of mechanical ventilation in the control groups was 17.1 | The mean duration of mechanical ventilation in the intervention groups was 0.59 higher (1.09 lower to 2.28 higher) | 1142 (5 studies) | ⊕⊝⊝⊝ very low4,5 | ||
| Barotrauma | Medium risk population1 | RR 0.82 (0.51 to 1.32) | 951 (7 studies) | ⊕⊝⊝⊝ very low2,4,5,7 | ||
| 131 per 1000 | 121 per 1000 (67 to 173) | |||||
| Hypotension | Medium risk population1 | RR 1.02 (0.54 to 1.90) | 392 (4 studies) | ⊕⊝⊝⊝ very low2,4,5,7 | ||
| 381 per 1000 | 389 per 1000 (206 to 724) | |||||
| *The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (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; RR: Risk ratio; ** Not shown:ventilator‐free days (very low quality 2,3,4,5, pooled analysis not performed due to extreme heterogeneity), endotracheal tube obstruction (very low quality2,4,5, pooled analysis not performed because all events occurred in one study), non‐clinical endpoints (i.e. physiologic endpoints, for example mean airway pressure, because these are not patient‐important outcomes). | ||||||
| GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate. | ||||||
1The basis of the assumed risk is the median risk in the control groups across trials. 2Downgraded for serious methodologic limitations (blinding was not possible in all studies; cross‐overs between treatment groups > 10% occurred in 3 trials; post‐randomization withdrawals ranging from 1.4% ‐ 17% occurred in 3 trials). 3Downgraded for inconsistency (moderate or high statistical heterogeneity). 4Downgraded for serious indirectness in the comparator (5 out of 10 trials included in this systematic review did not mandate low tidal volume conventional ventilation in participants who received conventional mechanical ventilation). 5Downgraded for imprecision (wide confidence intervals which include no benefit, and/or appreciable harm or benefit). With the exception of hospital or 30‐day mortality, the number of outcome events was low (i.e. fewer than 300). 6Although the event rate exceeded 300, and the sample size exceeded the optimal information size of 1290 (assuming alpha 0.05, beta 0.10, a baseline risk of death of 45%, and a 9% absolute reduction in risk), confidence intervals were wide and included no benefit (i.e. RR = 1) as well as both meaningful benefit and harm. We therefore downgraded this outcome due to serious imprecision. 7Downgraded for serious indirectness in the outcome (variable definition of treatment failures, hypotension, and barotrauma across studies).