Abnormal lipid peroxidation in patients with sleep apnoea.

The prevalence of cardiovascular diseases is increased in patients with the obstructive sleep apnoea syndrome (OSAS). The fall and rise of arterial oxygenation that follows each apnoea may increase lipid peroxidation and contributes to explaining this association. In the present study, the authors determined lipid peroxidation in patients with OSAS and the effect of treatment with continuous positive airway pressure (CPAP). Fourteen male patients with severe OSAS (59+/-5 apnoea x h(-1)) (+/-SEM) and 13 healthy nonsmoking, male volunteers of similar age were studied. Patients were studied at diagnosis and after treatment with CPAP for more than 1 yr (>4 h x night(-1)). A venous blood sample was obtained early in the morning after fasting all night. In patients with OSAS, a sample before and during sleep was also obtained. Low density lipoprotein (LDL) particles were isolated by sequential ultracentrifugation. Their level of oxidation was determined by the thiobarbituric acid assay (TBARs), and their susceptibility to oxidation by the lag phase measurement. Patients with OSAS showed higher TBARs (28.1+/-2.8 versus 20.0+/-1.8 nmol x malondialdehyde x mgLDL protein(-1), p=0.02) and shorter lag phase values (83.8+/-3.4 versus 99.7+/-3.4 min, p=0.005) than controls. These differences were not due to the smoking status of the patient. Likewise, these values did not change significantly throughout the night yet, the lag phase value was significantly improved by treatment with CPAP (124.9+/-8.5 min; p<0.001). These results indicate that obstructive sleep apnoea syndrome is associated with abnormal lipid peroxidation and that this is improved by chronic use of Continuous positive airway pressure. These results can contribute towards explaining the high prevalence of cardiovascular diseases seen in Obstructive sleep apnoea syndrome.