Patients with complex sleep apnea syndrome (CompSAS) have obstrucitve sleep apnea but develop central sleep apnea activity or Cheyne-Stokes-breathing when providet continuous positive airway pressure. We initiated a prospective study to identify pts wih CompSAS and to observe the natural course of CompSAS over a period of 3 mounth. 82 out of 675 pts (12,2%) developed CompSAS in the first night with stable nCPAP treatment. After 3 months 30 pts out of 436 pts (6,9%) showed CompSAS. Out of 54 pts with initial CompSAS available for follow-up, 40 (74%) did not have CompSAS in the follow-up PSG. 16 of the 382 pts (4,2%) without initial CompSAS available for follow up had CompSAS in the follow-up PSG. This finding means that CompSAS is not a stable disorder.
