Hypercoagulability in patients with obstructive sleep apnea

Background: Obstructive sleep apnea (OSA) has been linked to cardiovascular complications such as stroke and myocardial infarction. Previous studies demonstrate that OSA patients show elevated fibrinogen levels and increased platelet aggregation that are reversed with 1 night of nasal continuous positive airway pressure treatment (NCPAP). Questioning overall coagulability in OSA, we examined whole blood coagulability in 11 chronically NCPAP treated OSA subjects, 22 previously untreated OSA subjects, and in 16 of these after 1 night of NCPAP treatment. Patients and methods: During full polysomnography, subjects from each group had blood drawn prior to bedtime (21:00 h) and upon waking in the morning (07:00 h). Results: Untreated OSA patients had faster P. M. clotting times than chronically treated OSA patients (3.33 +/- 0.31 versus 6.12 +/- 0.66 min, P < 0.05 by ANOVA). A.M. values showed similar results (4.31 +/- 0.34 min versus 7.08 +/- 0.52 min, P < 0.05 by ANOVA) for the respective groups. One overnight treatment with nasal CPAP did not produce a significant change in A.M. whole blood coagulability (4.35 +/- 0.43 to 5.31 +/- 0.53 min; n = 16; P = 0.1) in 16 treated subjects. Conclusions: These data indicate a relationship between obstructive sleep apnea and blood hypercoagulability status that appears to be reversed by chronic NCPAP treatment. These data suggest that NCPAP might protect against the development of cardiovascular complications in OSA patients. (C) 2001 Elsevier Science B.V. All rights reserved.