A Cochrane review included 32 studies with a total of 2 916 subjects. Non-invasive positive pressure ventilation (NPPV), including continuous positive airway pressure (CPAP) and bilevel NPPV, was compared with standard medical care. NPPV (CPAP or bilevel NPPV) significantly reduced hospital mortality and endotracheal intubation with numbers needed to treat of 14 and 8, respectively (table ). There was no difference in hospital length of stay with NPPV, however, intensive care unit stay was reduced by 1 day. No significant increases in the incidence of acute myocardial infarction with NPPV during or after its application were observed. Fewer adverse events, in particular progressive respiratory distress and neurological failure (coma), were observed with NPPV use compared with standard medical care.
| Outcome | Relative effect (95% CI) | Assumed risk – Usual care | Corresponding risk - NPPV * | Participants (studies) |
|---|---|---|---|---|
| * NPPV = non-invasive positive pressure ventilation (CPAP and bilevel NPPV) | ||||
| Hospital mortality | RR 0.66 (0.48 to 0.89) | 204 per 1000 | 135 per 1000 (98 to 182) | 1 107 (20 studies) |
| Endotracheal intubation rate | RR 0.52 (0.36 to 0.75) | 249 per 1000 | 130 per 1000 (90 to 187) | 1 261 (22 studies) |
| Acute myocardial infarction (during intervention) | RR 1.24 (0.79 to 1.95) | 153 per 1000 | 190 per 1000 (121 to 299) | 461 (8 studies) |
| Acute myocardial infarction (after intervention) | RR 0.7 (0.11 to 4.26) | 26 per 1000 | 18 per 1000 (3 to 111) | 154 (4 studies) |
| Intolerance to allocated treatment | RR 0.47 (0.29 to 0.77) | 234 per 1000 | 110 per 1000 (68 to 180) | 1 848 (13 studies) |
| Hospital length of stay | The mean hospital length of stay in the intervention groups was 0.8 days lower (2.1 lower to 0.51 higher) | 542 (10 studies) | ||
| Intensive care unit length of stay | The mean intensive care unit length of stay in the intervention groups was 0.89 days lower (1.33 to 0.45 lower) | 222 (6 studies) | ||
There was lower hospital mortality (table ) and endotracheal intubation rate (table ) in CPAP-treated patients compared with standard care. Bilevel NPPV tended to lower hospital mortality and endotracheal intubation rate compared with standard care but the results were not statistically significant. No differences were found when CPAP and bilevel NPPV were compared directly.
| Comparison | Relative effect (95% CI) | Participants (studies) |
|---|---|---|
| NPPV = non-invasive positive pressure ventilation | ||
| CPAP versus standard care | RR 0.60 (0.39 to 0.94) | 699 (13 studies) |
| Bilevel NPPV versus standard care | RR 0.65 (0.39 to 1.09) | 506 (11 studies) |
| CPAP versus bilevel NPPV | RR 1.10 (0.61 to 1.97) | 694 (12 studies) |
| Comparison | Relative effect (95% CI) | Participants (studies) |
|---|---|---|
| NPPV = non-invasive positive pressure ventilation | ||
| CPAP versus standard care | RR 0.47 (0.33 to 0.67) | 825 (14 studies) |
| Bilevel NPPV versus standard care | RR 0.55 (0.26 to 1.17) | 536 (12 studies) |
| CPAP versus bilevel NPPV | RR 1.04 (0.55 to 1.97) | 721 (13 studies) |
Comment: The authors state that CPAP can be considered the first option in selection of NPPV due to more robust evidence for its effectiveness and safety and lower costs compared with bilevel NPPV.