Central sleep apnea: The complex sleep apnea syndrome (CompSAS)

The CompSAS is now classified as a variant of CSA. Although it is not likely to be diagnosed before stabilizing the airway of patients with OSA during a diagnostic study, the physiologic substrate for CompSAS is present before initiation of CPAP, as evidenced by the ability to identify patients likely to develop CompSAS using analysis of cardiopulmonary coupling, and by its occurrence in patients whose OSA is treated using oral appliances. Treatment of CompSAS for now is aimed at correction of indices that indicate SDB, namely, normalization of the ventilatory pattern as evidenced by a reduced AHI and by smoothing of ventilatory effort. More meaningful outcomes of therapy, such as improved alertness, cognition, and cardiovascular outcomes, await further large prospective randomized controlled trials, but for now, it seems reasonable to apply principles similar to those applied when assessing adequacy of outcomes for OSA and CSA. For most patients, this will likely mean a trial of CPAP to stabilize the upper airway, and then in those who do not normalize their breathing pattern, or who are deemed unlikely to normalize their breathing pattern, treatment with ASV, or other therapies aimed at altering ventilatory control.