Effects of continuous positive airway pressure on very short-term blood pressure variability associated with sleep-disordered breathing by pulse transit time-based blood pressure measurements

Abstract

Background: Blood pressure (BP) variability (BPV) is a predictor of cardiovascular outcomes independently of BP absolute values. We previously reported that pulse transit time (PTT) enables monitoring beat-to-beat BP, identifying a strong relationship between the extent of very short-term BPV and the severity of sleep-disordered breathing (SDB). Here, we investigated the effects of continuous positive airway pressure (CPAP) on very short-term BPV. Methods: We studied 66 patients (mean age 62 years old, 73% male) with newly diagnosed SDB who underwent full polysomnography on two consecutive days for diagnosis (baseline) and CPAP, together with PTT-driven BP continuous recording. PTT index was defined as the average number of acute transient rises in BP (≥12 mmHg) within 30 s/h. Results: CPAP treatment effectively improved SDB parameters, and attenuated PTT-based BP absolute values during the night-time. Very short-term BPV that includes PTT index and standard deviation (SD) of systolic PTT-BP was significantly reduced by CPAP therapy. The changes in PTT index from baseline to CPAP were positively correlated with the changes in apnea-hypopnea index, obstructive apnea index (OAI), oxygen desaturation index, minimal SpO2, and mean SpO2. Multivariate regression analysis revealed that changes in OAI and minimal SpO2, as well as heart failure, were the independent factors in determining the reduction of PTT index following CPAP. Conclusion: PTT-driven BP monitoring discovered the favorable effects of CPAP on very short-term BPV associated with SDB events. Targeting very short-term BPV may be a novel approach to identifying individuals who experience greater benefits from CPAP.