Change and significance of 8-isoprostane in exhaled breath condensate in obstructive sleep apnea-hypopnea syndrome

Objective To study the changes of 8-isoprostane(8-isoPG) in exhaled breath condensate (EBC) in patients of obstructive sleep apnea-hypopnea syndrome (OSAHS) and discuss their clinic significance. Methods Forty OSAHS patients and 30 normal controls were included in the study. EBC before and after polysomnography(PSG) were collected by Ecosreen made in JAEGER Company in German. Serum after PSG was collected as well. EBC and serum 8-isoPG were measured by enzyme-linked immunosorbent assay. Results The concentration of 8-isoPG in EBC was (13.08±1.42) ng/L before PSG, (14.93±1.39) ng/L after PSG in 40 OSAHS patients( P 0.05 ). The concentration of 8-isoPG in EBC after PSG was significantly higher than that in normal controls ( P<0.01 ). The serum level of 8-isoPG was significantly higher in 40 OSAHS patients than that in 30 normal controls,(36.59±14.89) ng/L vs (19. 91±7.76) ng/L ( P<0.01). The concentration of 8-isoPG in EBC of OSAHS patients after PSG was correlated positively with serum 8-isoPG level ( r=0. 685, P<0.01). The concentration of 8-isoPG in EBC of OSAHS patients after PSG was correlated positively with AHI ( r=0.650, P<0.01) and negatively with LSpO2 ,FSpO2, MSpO2(r =-0.406,-0.439, -0.454,all P <0.05). Conclusions These findings suggest that oxidative stress is characteristic in OSAHS patients. The level of 8-isoPG in EBC depends on the severity of the OSAHS and may prove to be useful in monitoring of airway oxidative stress of OSAHS. Key words: Obstructive sleep apnea-hypopnea syndrome; Exhaled breath condensate; 8-isoprostane