Contribution of central sleep apnea to severe sleep apnea hypopnea syndrome

PURPOSE: Central sleep apnea (CSA) is usually distinguished from obstructive sleep apnea (OSA). In fact, CSA is often a component of severe sleep apnea hypopnea syndrome (SAHS), rather than occurring alone. We investigated the clinical characteristics and polysomnography (PSG) parameters of CSA components in patients with severe SAHS. METHODS: The clinical characteristics and PSG parameters were retrospectively analyzed. RESULTS: Pure or dominant CSA was rare (5% of all patients). Of all patients with CSA, 72% also exhibited other apnea subtypes that contributed to severe SAHS. Among patients with severe SAHS, those with CSA were more likely than others to be older; thinner; exhibit higher prevalences of comorbid coronary heart disease, arrhythmia, and heart failure; a higher apnea/hypopnea index (AHI); mixed apnea index (MAI); an elevated oxygen desaturation index (ODI); and more nighttime oxygen saturation levels < 90%. Multivariate logistic regression analysis revealed that older age, comorbid arrhythmia or heart failure, and an elevated ODI were independently associated with CSA. CONCLUSION: Patients who complain of snoring or apnea may be better evaluated by comprehensive PSG prior to treatment if they are old, show greater hypoxia, or suffer from arrhythmia and/or heart failure, because such patients are more likely than others to exhibit CSA.