Adaptive servoventilation versus noninvasive positive pressure ventilation for central, mixed, and complex sleep apnea syndromes

Rationale: Although continuous positive airway pressure (CPAP) is most often effective in patients with obstructive sleep apnea, optimal treatment of patients with predominantly mixed apneas, central sleep apnea syndrome/Cheyne-Stokes respiration (CSA/CSR), or complex sleep apnea (CompSAS) is less straightforward, and may require alternative ventilatory assist modalities. Objectives: To compare the efficacy of noninvasive positive pressure ventilation (NPPV) with adaptive servoventilation (ASV) in treating patients with centrally mediated breathing abnormalities. We hypothesized that NPPV and ASV would be equivalently efficacious in improving the apnea/hypopnea index (AHI) and respiratory arousal index (RAI). Methods: Prospective randomized crossover clinical trial comparing NPPV with ASV in patients with CSA/CSR, predominantly mixed apneas, and CompSAS in an acute setting. Measurements and Main Results: 21 patients (6 with CSA/CSR, 6 with predominantly mixed apneas, and 9 with CompSAS) with initial diagnostic AHI standard deviation 51.9 +/- 22.8/hr and RAI 45.5 +/- 26.5/hr completed the study. Following optimal titration with CPAP (N=15), disturbed breathing and disturbed sleep remained high with mean AHI=34.3 +/- 25.7 and RAI=32.1 +/- 29.7. AHI and RAI were markedly reduced with both NPPV (6.2 +/- 7.6 and 6.4 +/- 8.2) and ASV (0.8 +/- 2.4 and 2.4 +/- 4.5). Treatment AHI and RAI were both significantly lower using ASV (P<0.01). Conclusions: These data confirm that in patients with CSA/CSR, mixed apneas, and CompSAS, both NPPV and ASV are effective in normalizing breathing and sleep parameters, and that ASV does so more effectively than NPPV in these types of patients.