The association between exhaled nitric oxide and sleep apnea: the role of BMI.


BACKGROUND Obstructive sleep apnea syndrome is associated with airway inflammation. Measurement of exhaled nitric oxide is a non-invasive method for evaluation of airway diseases. It seems that obesity is an exacerbating factor for airway inflammation. We aimed to evaluate the changes of exhaled nitric oxide after sleep in patients suffering from OSA regarding BMI. METHOD In 54 patients referred for polysomnography, exhaled nitric oxide measurements were performed before and after sleep. Subjects were divided into three categories: normal, obese with sleep apnea and non-obese, based on polysomnographic recordings and BMI. RESULTS 47 subjects had abnormal apnea/hypopnea index (AHI mean = 39.7) and 7 were normal regarding AHI (AHI mean = 3.0). BMI was significantly correlated to AHI, number of desaturations and hypoxia. Among those with apnea, 31 subjects were obese and 16 were non-obese. Exhaled nitric oxide levels in normal and OSA subjects showed no significant change, but a significant increase was found in obese patients with apnea (14.7 pre-sleep mean, 20.0 post-sleep mean). CONCLUSIONS Obesity is an effective factor in the inflammation of airways in patients with obstructive apnea.


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