Abstract
Sleep disordered breathing (SDB) has been identified as mortality risk factor in patients with cardiovascular disease. Although the severity of SDB is quantified primarily by the apnea-hypopnea index (AHI), the average number of apneas and hypopneas per hour of sleep, it is not clear whether the AHI is a reliable index to evaluate an increased mortality risk associated with SDB in cardiovascular disease patients. To address this problem, we analyzed polysomnogram (PSG) data including nasal flow and pulse oximetry (SpO2) level signals, and studied the association between characteristics of the PSG data and mortality in cardiovascular disease patients (n=112) with central sleep apnea due to Cheyne-Stokes breathing pattern. Compared to airflow-related parameters such as AHI, SpO2 level-related parameters, such as cumulative time rate with desaturation episodes, was stronger predictors of all-cause mortality. This result suggests that characteristics of SpO2 level drop related with SDB provide more important information to predict the mortality risk in cardiovascular disease patients than conventional AHI.
