Abstract
Introduction
The state of sleep is characterized by unloading of the autonomic nervous system and represents an opportunity to investigate the properties of the cardiovascular (CV) system. We investigated overnight pulse propagation time (PPT) as an indirect measure of vascular stiffness during sleep and its association with daytime blood pressure (BP).
Methods
The digital pulse wave, derived from finger oximetry, was recorded during sleep in 495 subjects (169 females, age 54±12 y, BMI 30±6 kg/m2, AHI 19±23 n/h) referred to five sleep centers. Office BP and established CV risk factors were assessed. PPT was calculated as the time between the top and the subsequent dichotic notch of the digital pulse wave. Mean PPT across the entire sleep period was calculated.
Results
PPT was associated with age, systolic BP, diastolic BP, the number of apneic as well as hypoxic events during sleep (r=-0.54, -0.19, -0.21, -0.13, and -0.11, p<0.01 respectively). PPT was lower in patients with hypertension compared to normotensives (160±34 ms vs. 178± 47 ms, p<0.001). In a multivariate analysis, PPT was independently associated with age, height, waist, smoking, hypertension and diabetes but not sleep apnea indices.
Conclusions
PPT determined by overnight oximetry reflects daytime BP and presence of hypertension. Assessment of PPT during sleep may be a useful tool for classification of overall CV function and risk.
The study was supported by Weinmann GMBH, the Swedish Heart and Lung Foundation and the University of Gothenburg.
- © 2012 ERS