Complex Sleep Apnea

Abstract

The term complex sleep apnea syndrome (Comp-SAS) refers to a specific variant of respiratory impairment during sleep characterized by the appearance or significant increases in the number of episodes of central apnea and hypopnea after starting CPAP therapy for obstructive sleep apnea syndrome (OSAS). The mechanisms producing Comp-SAS are not fully understood. It is possible that respiration with positive pressure and elimination of pharyngeal obstruction in some patients lead to increases in pulmonary ventilation and decreases in PaCO2 to below the individual threshold required for stimulating respiration. The prevalence of Comp-SAS is 5–20% of patients with OSAS receiving CPAP therapy. Significant clinical predictors for Comp-SAS have not been established, though this respiratory disorder is known to occur more frequently in male patients, older patients, those with severe OSAS, and those with cardiovascular diseases such as ischemic heart diseases, atrial fibrillation, or chronic heart failure (CHF). In most cases, Comp-SAS settles spontaneously after 1–2 months of regular CPAP therapy. If positive pressure treatment has no effect, other contemporary treatment methods can be used, such as adaptive servo ventilation or BPAP treatment with controlled respiratory frequency, though these are contraindicated in systolic heart failure. The question of whether treatment of patients with Comp-SAS is obligatory when the course of illness is straightforward and symptom-free remains open.