Plasma levels of platelet-derived microparticles in patients with obstructive sleep apnea syndrome.

Aim: Obstructive sleep apnea syndrome (OSAS) has been associated with high cardiovascular morbidity and mortality, and patients suffer from repeated episodes of hypoxia. Platelet-derived microparticles (PDMPs) are released via platelet activation by various agonists, including inflammatory cytokines or high shear stress. Plasminogen activator inhibitor -1 (PAI-1) is a fibrinolytic marker and soluble fibrin (SF) is a coagulation activation marker. We examined plasma levels of PDMPs, PAI-1 and SF in patients with OSAS. We also examined the effects of continuous positive airway pressure (CPAP) on plasma levels of PDMPs.

Methods: Full polysomnography (PSG) monitoring was performed on 27 patients. The apneahypopnea index (AHI) of 5 events/h or less than 30 events/h indicated mild to moderate OSAS, and an AHI of 30 events/h or more indicated severe OSAS. Plasma levels of PDMPs were measured using an ELISA kit, and PAI and SF were determined by a latex immunoassay. In addition, the effects of CPAP treatment were studied in 7 patients.

Result: The plasma level of PDMPs was significantly higher in patients with severe OSAS (15.8±10.4 U/mL) than normal controls (10.8±7.1 U/mL, p < 0.05) and patients with mild to moderate OSAS (9.2±3.5 U/mL, p < 0.05). The plasma levels of PDMPs correlated with the AHI (r = 0.39, p < 0.05). In addition, CPAP treatment decreased the plasma level of PDMPs (11.9±5.6 U/mL to 6.7±3.2 U/mL, p < 0.05).

Conclusions: Patients with OSAS might be at increased cardiovascular risk due to elevated PDMPs. Moreover a decrease in the plasma level of PDMPs by treatment with CPAP might reduce cardiovascular risk.