Lungen- und Atemwegsmedizin

Clinical Factors and Biomarkers Associated with the Non-Dipping Profile in Obstructive Sleep Apnea Patients with Metabolic Syndrome

Abstract

Radostina Vlaeva Cherneva, Ognian Borisov Georgiev, Daniela Stoichkova Petrova, Emil Ivanov Mano, Adelina Dimitrova Tsakova and Julia Ivanova Petrova

Background: Patients with obstructive sleep apnea are more likely to have a non-dipping blood pressure profile than hypertensive patients without sleep apnea. The study of clinical factors and biomarkers affecting the nocturnal dip of blood pressure is of practical value.

Aim: To determine the role of glucometabolic, sleep study parameters and biomarkers in the detection of dipper and non-dipper obstructive sleep apnea patients.

Materials and Methods: A total of 87 patients participated in the study. Obstructive sleep apnea was verified by a standard polysomnography. Metabolic syndrome was diagnosed according to IDF, 2005. Anthropological parameters, glucmetabolic and sleep study characteristics were assessed. An ambulatory 24-hour blood pressure monitoring was performed. Resistin and free fatty acids plasma levels were measured. Urinary 8-isoprostanes were determined.

Results: Nondippers did not differ significantly from dippers regarding the anthromopetric measurements. From the sleep study parameters only the duration of sleep at SaO2<90% was longer in non-dippers (63.17 ± 30.32 vs 39.92 ± 34.89). Glucometabolic markers could not differentiate dippers from non-dippers, except for HbA1C (5.9 ± 0.5 vs 6.4 ± 1.05; p=0.006). The biomarkers – resistin, free fatty acids and isoprostanes were of similar range in both groups. The multivariate regression analysis, however showed that HbA1C lost its value as an independent predictor of non-dipping after adjustment for duration of sleep at SaO2<90%.

Conclusions: According to our study the average duration of sleep with SatO2<90% could be of clinical value in the prediction of the non-dipping phenomenon in patients with obstructive sleep apnea and metabolic syndrome.