Assessment of the relationship between the level of oxidative stress and the apnea-hypopnea index in patients with obstructive sleep apnea

Obstructive sleep apnea (OSA) is a disorder with the reported prevalence of between 9 % and 38 % in the community. Polysomnography (PSG), still considered as the golden standard in the diagnosis of OUA, is a cumbersome, time-consuming and expensive test requiring sophisticated equipments, trained and well-educated personnel. There is a need for cheaper, more practical, simpler tests for the screeining and diagnosis. As a candidate test to be considered in screening and diagnosis, we evaluated the value of measurement of urinary 8-isoprostane concentrations for this purpose. We sought to analyze the relationship of the urinary concentrations of 8-isoprostane with some polysomnographic parameters. To this end, we recruited 41 patients without any known history of systemic illnesses with complaints of simple snore, daytime sleepiness, apnea witnessed by bedtime partners and being considered or referred with the suspicion of OSA. After full-night PSG study, we collected their urine samples and analyzed for the concentrations of 8-isoprostane. Moreover, blood samples were taken from the 37 out of 41 patients who gave consent for drawing blood and further evaluation. After statistical analysis, we failed to find any correlation between 8-isoprostane concentrations and PSG parameters such as apnea-hypopnea index (AHI), mean apnea duration, maximum apnea duration, mean O2 saturation, minimum O2 saturation, duration of sleep time with less than 90 % O2 saturation and oxygen desaturation index (ODI). However, plasma malondialdehyde (MDA) levels were correlated with these parameters and reflected the severity of OSA. As a result we had found that, urinary 8-isoprostane concentrations had no value in the screening and the diagnosis of OSA in the population, but plasma MDA levels might have a role in this regard. Keywords: obstructive sleep apnea, oxidative stress, polysomnography, isoprostanes, malondialdehyde