Clinical impact of sleep-disordered breathing on very short-term blood pressure variability determined by pulse transit time

Background: Sleep-disordered breathing (SDB) and blood pressure variability (BPV) are strongly associated with cardiovascular diseases. Recently, pulse transit time (PTT) has enabled the monitoring of beat-to-beat BP; however, little is known about its clinical utility. The present study aimed to clarify the impact of SDB on very short-term BPV determined by PTT-based BP monitoring (PTT-BP). Methods: We analyzed 242 patients with suspected SDB. PTT-BP was continuously recorded overnight together with a portable sleep monitor. PTT index was defined as the average number of transient rises in PTT-BP (>= 12 mmHg) within 30 s/h. We compared PTT-BP values with each SDB parameter, and examined the association between BPV and subclinical organ damage. Results: Standard deviation (SD) of systolic, mean or diastolic PTT-BP, which indicates very short-term BPV, was significantly correlated with apnea--hypopnea index (AHI) and oxygen desaturation index (ODI). PTT index was positively associated with AHI, ODI, and minimal SpO(2). Regression analyses showed that AHI and ODI were significant variables to determine systolic, mean, or diastolic PTT-BP SD and PTT index. Logistic regression analyses demonstrated that diastolic PTT-BP SD significantly influenced the presence of chronic kidney disease and left ventricular hypertrophy. Conclusion: SDB severity was closely associated with very short-term BP variability, and diastolic PTT-BP SD might be an important factor linked to subclinical organ damage. PTT-BP measurement may be useful to evaluate very short-term BPV during the night.