Correlation between lung volume and the severity of obstructive sleep apnea hypopnea syndrome in obese patients

Objective To examine the relationship between the severity of obstructive sleep apnea hypopnea syndrome （OSAHS）, lung volume and obesity. Methods The study included 60 adult male obese patients with OSAHS determined by overnight polysomnogram （PSG） using American Academy of Sleep Medicine-defined criteria. Lung volume measurements were made in maximum vital capacity （VCmax）, forced vital capacity （FVC） , maximum voluntary ventilation （MVV） , functional residual capacity （FRC） and total lung capacity （TLC）. Results The aponea hypopnea index（AHI） were negatively correlated with FVC, MVV, VCmax （r were -0. 533, -0.276 and -0.575, P <0.01 or P <0.05）. But the lowest arterial oxygen saturation （LSaO2） and the mean arterial oxygen saturation （MSaO2） were positively correlated with FVC, MVV and VCmax （r were 0.299, 0.435,0.412, and 0.344, 0.474, 0.457, P < 0.01 or P < 0.05）. The body mass index （BMI） were positively correlated with AHI （r = 0.728, r2 = 0.530, P <0.01）. The FVC, MVV, VCmax, LSaO2 and MSaO2 varied inversely with BMI. FRC and TLC had no relation with AHI, LSaO2, MSaO2 and BMI. Conclusions There are significant correlations among obesity, dynamic lung volume and OSAHS severity. This result suggests that changes in dynamic lung volume may play an important role in the pathogenesis of OSAHS in obese patients. Key words: Sleep apnea, obstructive; Lung volume measurements; Obesity