Purpose: This study was made to evaluate the effect of automatic continuous positive airway pressure (auto-CPAP) versus fixed continuous positive airway pressure (fixed CPAP) in reducing the apnea-hypopnea index (AHI) and the mean therapy pressure, improving subjective sleepiness, sleep architecture, patient compliance, and preference in patients with obstructive sleep apnea.
Methods: We searched the electronic databases MEDLINE, EMBASE, the Cochrane Library, and Google Scholar. Randomized controlled trials comparing auto-CPAP with fixed CPAP were reviewed. Continuous variables were presented as mean difference (MD), and dichotomous data as odds ratio (OR), both with 95% confidence intervals (CI).
Results: We identified 19 studies consisting of 845 patients. Compared to fixed CPAP, the use of auto-CPAP reduced mean therapy pressure (MD -1.64; 95% CI -2.46 to -0.82), improved patient compliance (MD 0.23; 95% CI 0.06 to 0.39), increased the percentage of total sleep time (TST) in slow wave sleep (MD 5.11; 95% CI 1.34 to 8.88), and decreased the percentage of TST in stage 2 sleep (MD -4.75; 95% CI -9.38 to -0.11). Moreover, more patients preferred auto-CPAP therapy (OR 3.65; 95% CI 1.27 to 10.53). There were nonsignificant trends towards better outcomes with auto-CPAP for AHI and Epworth Sleepiness Scale (MD -0.43; 95% CI -1.10 to 0.23, and MD -0.24; 95% CI -0.74 to 0.25, respectively), though these are of questionable clinical significance.
Conclusions: There are some aspects of clinical care, such as a mild improvement in compliance, patient preference, and sleep architecture that appear to favor the use of auto-CPAP compared to fixed CPAP. The clinical relevance of these findings requires further study.