A Cochrane review [Abstract] 1 included 10 studies with a total of 173 subjects. The pooled risk ratio (RR) of dying was 0.62 (95% CI 0.42 to 0.91; 4 studies) in favour of nocturnal mechanical ventilation compared to spontaneous breathing. The pooled RR of unplanned hospitalization was 0.25 (95% CI 0.08 to 0.82; 2 studies) in favour of nocturnal mechanical ventilation. For most of the outcome measures there was no significant long-term difference between nocturnal mechanical ventilation and no ventilation.
Volume-cycled ventilation as compared with pressure-cycled ventilation was associated with less sleep time spent with an arterial oxygen saturation below 90% (mean difference [MD] 6.83 minutes, 95% CI 4.68 to 8.98; p = 0.00001; 2 cross-over trials) and a lower apnoea-hypopnoea (per sleep hour) index (MD -0.65, 95% CI -0.84 to -0.46, p = 0.00001). No studies comparing invasive and non-invasive mechanical ventilation or intermittent positive pressure versus negative pressure ventilation were found.
Comment: The quality of evidence is downgraded by inconsistency (heterogeneity in studied patients, interventions and outcomes) and by imprecise results (limited study size for each comparison).
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