Continuous positive airway pressure (CPAP) is first-line therapy for sleep-related breathing disorders (SRBDs). Obstructive sleep apnea (OSA) is the major player in the SRBDs space, with a prevalence approaching 100% in adult men using current diagnostic criteria. Patients with OSA and comorbid cardiovascular disease (CVD) are diagnosed with OSA syndrome, and CPAP is prescribed. Primary care physicians and cardiologists are quick to refer patients with CVD to sleep docs to see whether CPAP can improve CVD-related outcomes.
What the Studies Show
There's a problem though. CPAP doesn't seem to improve CVD-related outcomes. In some cases, it's even harmful. Let's do a quick review. In 2005, the CANPAP study found CPAP didn't improve a composite CVD outcome that included mortality. A post hoc analysis found that it actually increased mortality if central apneas weren't eliminated. The post hoc analysis also found benefit when central apneas were eliminated, but for all-comers, CPAP didn't improve outcomes. Strike one.
Enter adaptive servo-ventilation (ASV). If CANPAP showed success depended on eliminating central apneas, why not use ASV for all patients with CVD and central apneas or Cheyne-Stokes respirations? ASV eliminates central apneas and Cheyne-Stokes. Well, that didn't work either. The randomized, controlled SERVE-HF trialpublished in 2015, showed that ASV increases all-cause and CVD-specific mortality.
