Effect of truncal obesity on airway resistance

Background and objective Truncal obesity can influence respiratory mechanisms regardless of BMI. This study evaluated the impact of truncal obesity on both spirometry and impulse oscillometry (IOS). Patients and methods The study included 102 patients recruited from the Outpatient Department of Ain Shams University Hospital. All patients were subjected to clinical examination, anthropometric measurements, IOS, and spirometry. According to BMI, the patients were categorized into the obese group (71 patients) and the nonobese group (31 patients). The obese group was subclassified into overweight, obese, and morbidly obese groups. The obese subgroup was reclassified according to waist to hip ratio (WHR) into the truncal obese group (41 patients) and the nontruncal obese group (30 patients). The data collected were comparatively analyzed using either the independent-samples t -test or one-way analysis of variance. Pearson’s correlation coefficient was used to study the correlations between data. Multiple linear regression analysis was carried out to examine the simultaneous influences of anthropometric measures on the IOS data. Results There were significant differences in IOS and spirometry data between the obese and nonobese groups as well as among the four groups. Regarding WHR, there were significant correlations with IOS data and negative correlations with spirometry data except maximal mid expiratory flow. Using multiple linear regression analysis, it was revealed that WHR was the most powerful predictor for R5. BMI followed by WHR was the most powerful predictor for R5–R20. Conclusion Truncal obesity significantly affects airway resistance, as evaluated by spirometry and IOS.