Polysomnographic characterization of circadian blood pressure patterns in patients with obstructive sleep apnea.

We characterized the polysomnography (PSG) parameters associated with alterations in the circadian blood pressure (BP) pattern aiming to identify the main contributors to explain the nondipper profile in obstructive sleep apnea (OSA). This is an observational prospective-multicenter study that included participants referred to the sleep unit for suspected OSA. Following a PSG study, subjects with an apnea-hypopnea index (AHI) ≥5 events/hr were included. Two groups were established based on the 24-hr ambulatory blood pressure monitoring dipping ratio (DR; night/day BP ratio): dippers (DR ≤ 0.9) and nondippers (DR > 0.9). The cohort consisted of 299 patients: 131 (43.8%) dippers and 168 (56.2%) nondippers. A significant increase in the risk of presenting a nondipper BP pattern was found along with AHI gain [odds ratio (OR) (95% CI) = 1.71 (1.28 to 2.28)]. The best AHI cutoff for predicting nondipper status was 25.2 events/hr, increasing the OR (95% CI) to 3.50 (2.02 to 6.07). The hypopnea index [OR (95% CI) = 1.70 (1.27 to 2.26)], TSat90 [OR (95% CI) = 1.41 (1.06 to 1.87)], and respiratory arousal index [OR (95% CI) = 1.74 (1.30 to 2.34)] were individually associated with the risk of a nondipping pattern. Multivariate variable selection processes identified the respiratory arousal index as the most relevant risk factor for the nondipper profile, beyond classical clinical risk factors and usual PSG metrics.