Mean platelet volume and effect of CPAP therapy in obstructive sleep apnea syndrome

Introduction and Aim: Previous studies have supported that Obstructive Sleep Apnea Syndrome (OSAS) is an independent risk factor for cardiovascular diseases. Platelets play a key role in cardiovascular diseases. It was emphasized that increased platelet activation in patients with OSAS may be an important reason of commonly seen cardiovascular complications. Mean platelet volume (MPV) is a parameter that shows platelet function and activation. In this study; we aimed to evaluate MPV, which is an indirect indicator of platelet activation, and effect of CPAP therapy on MPV in patients with OSAS. Method: Consecutively two hundred patient?s records, who applied to sleep laboratuary of Düzce University Medical Faculty Department of Chest Diseases with OSAS clinic and underwent overnight polysomnography (PSG), were retrospectively examined. 158 patient, whose blood counts and MPV values were measured, were taken into the study. Patients were categorized into four groups according to apnea hipoapnea index (AHI). Groups were compared to demographical and clinical characteristics, polysomnographic datas, blood count parameters and MPV values. At the same time, in order to show the effect of OSAS therapy on MPV, a change in MPV was searched in severe OSAS cases (20 cases) who took one month of regular CPAP therapy and whose blood counts were measured. Results: Totally 158 subjects 51 women (%32,3) 107 men (%67,7) were enrolled in this study. Median age was 51±13 (min-16, max-82). OSAS was diagnosed in %74,1 (117/158) of the cases. Mild OSAS was 32 (%20.3), moderate OSAS was 28 (%17.7) and severe OSAS was 57 (%36.1) of the cases. Mean age was similar between the groups. Statistically significant increase was found between OSAS severity and BMI, neck circumference and Epworth Sleepiness Scale, snoring percent during sleep, the amount of desaturation below 90 percent during sleep, desaturation index, hemoglobin and hematocryte values from blood parameters. There was no statistically significant difference between the groups in terms of platelet count and sleep efficiency. Mean platelet volume was found significantly lower in cases with severe OSAS when compared with mild OSAS group and subjects without OSAS (p=0.001). Negative corelation was found between MPV and AHI, desaturation index, the amount of desaturation below 90 percent during sleep, and positive corelation was found between sleep efficiency and LDH. There were no statistically significant differences between MPV values according to sex, smoking and alcohol usage, comorbidities (DM, Hypercholesterolemia) and medication (ACE inhibitor, ß-blocker, Ca-channel blocker, diuretic, aspirin). In severe OSAS group after one month of CPAP therapy MPV was significantly decreased as to before therapy (p=0.021). There were no statistically significant differences in terms of median erythrocyte and platelet count, hematocryte percentage and hemoglobin values. Conclusion: Results of the study don?t support the increase in MPV and consequently in platelet activation in severe OSAS cases compared to the control group. Conversely, results of this study have shown that one month of CPAP therapy has reduced MPV and so platelet activation in severe OSAS cases. Related to this subject controlled, prospective studies containing therapy results over large series is required. Key Words: sleep apnea; obstructive sleep apnea; mean platelet volume; apnea-hipoapnea index; platelet activation.