• Xue-mei Liao and Qin Yu.
• Department of Respiratory Medicine, First Hospital, Lanzhou University, Lanzhou 730000, China.
• Zhonghua Jie He He Hu Xi Za Zhi. 2005 Jun 1; 28 (6): 368-71.

ObjectiveTo explore the changes and implications of plasma orexin-A levels in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS).MethodsPolysomnography was performed in 30 obese OSAHS patients (OSAHS group), 30 obese subjects (obese group) and 20 normal healthy adults (control group). In both the OSAHS group and the obese group the body mass index (BMI) was higher than 25, and there was no significant difference in BMI. The plasma was deproteinized by chromatography, and the level of orexin-A was determined by radioimmunoassay.ResultsThe plasma orexin-A level in the OSAHS group [(9.0 +/- 1.8) ng/L] was significantly higher than those in the obese group [(7.2 +/- 1.4) ng/L, P < 0.01] and the control group [(6.7 +/- 1.6) ng/L, P < 0.01] respectively. Plasma orexin-A levels in patients with OSAHS correlated positively with the AHI (r = 0.639, P < 0.01), and the arousal index (r = 0.435, P < 0.05), but correlated negatively with the lowest oxygen saturation (LSaO(2)) (r = -0.521, P < 0.01) and the mean oxygen saturation (MSaO(2)) (r = -0.589, P < 0.01). The BMI in the OSAHS group and the obese group did not correlate significantly with the orexin-A levels (r = 0.132, P > 0.05).ConclusionsThe plasma orexin-A levels in OSAHS patients are increased which may be caused by repeated nocturnal hypoxia due to OSAHS. Orexin-A may play a crucial role in the regulation of the sleep-arousal process.

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