Parameters of Overnight Pulse Wave under Treatment in Obstructive Sleep Apnea.

BACKGROUND Sleep-related breathing disorders may promote cardiovascular (CV) diseases. A novel and differentiated approach to overnight photoplethysmographic pulse wave analysis, which includes risk assessment and measurement of various pulse wave characteristics, has been evaluated in obstructive sleep apnea (OSA). OBJECTIVES The purpose of this study was to assess if and which of the differentiated pulse wave characteristics might be influenced by OSA treatment with positive airway pressure (PAP). METHODS The study included two protocols. In the case-control study (group A), pulse wave-derived CV risk indices recorded during PAP therapy were compared with those obtained in age, body mass index, and CV risk class-matched patients with untreated OSA (n = 67/67). In the prospective PAP treatment study (group B), 17 unselected patients undergoing a full-night sleep test at baseline and after 23 ± 19 weeks of treatment were analyzed. RESULTS In untreated OSA patients (group A), the overnight hypoxic load was increased (SpO2 index 38.7 ± 17.5 vs. 24.0 ± 11.1, p < 0.001) and the pulse wave attenuation index (PWA-I) was lower (29.4 ± 9.2 vs. 33.5 ± 11.8, p = 0.022) than in treated patients. In group B, PAP therapy reduced the hypoxic load and increased the PWA-I significantly. The composite CV risk index was slightly but not significantly reduced. CONCLUSIONS PAP therapy modified the hypoxic load and pulse wave-derived markers. The PWA-I - associated with sympathetic vascular tone - was most prominently modified by PAP. This novel approach to markers of CV function should be further evaluated in prospective studies.