EFFECTS OF NCPAP THERAPY ON FIBRINOGEN LEVELS IN OBSTRUCTIVE SLEEP-APNEA SYNDROME

In patients with obstructive sleep apnea syndrome (OSAS), the blood co agulation system may contribute to an increased risk of cardiovascular events, which occur most frequently in the morning. Nasal continuous positive airway pressure (NCPAP) treatment can improve the mortality o f patients with OSAS. We measured the plasma fibrinogen concentration, which is an independent risk factor for cardiovascular events, in the afternoon (3:30 P.M.) and the next morning upon awakening (8:30 A.M.) in 11 patients with OSAS (apnea and hypopnea index > 20) before and a fter NCPAP therapy. We also measured the hematocrit, the C-reactive pr otein, and the total plasma protein at the same time. The plasma fibri nogen and hematocrit levels in the morning (298 +/- 16 mg/dl and 48.5 +/- 1.5%, mean +/- SEM) were significantly higher than on the previous afternoon (275 +/- 14 mg/dl and 46.6 +/- 1.3%) (fibrinogen, p < 0.02; hematocrit, p < 0.005). The whole blood viscosity (WBV) at a shear ra te of 208 inverse seconds, which can be predicted based on the hematoc rit and total plasma protein, was also significantly higher in the mor ning (4.98 +/- 0.20/s) than in the afternoon (4.73 +/- 0.17/s) (p < 0. 005). These increases in the plasma fibrinogen concentration and the W BV in the morning disappeared after NCPAP treatment. The attenuation o f morning increases in the plasma fibrinogen concentration and WBV ind uced by NCPAP treatment may contribute to an overall improvement in th e mortality from cardiovascular events in patients with OSAS.