Effect of obesity on pulmonary function in children

The effect of obesity on pulmonary function was studied in 13 children, aged 8‐15 years, with 147‐300% ideal body weight (IBW). Measurements included lung volumes, airflow rates pre‐ and post‐bronchodilator nebulization, diffusing capacity (D LCO ), maximal voluntary ventilation (MW), minute ventilation V̇ E ), and resting energy expenditure (REE). When compared with predicted normal values for sex, height, and body surface area (BSA), decreases (mean % predicted,±SE) were observed in expiratory reserve volume (ERV, 36±5); forced expiratory volume in 1 second (FEV 1 , 73±5); forced expiratory flow between 25% and 75% of vital capacity (FEF 25‐75% 70±6); D LCO , absolute (52±3) and corrected (D LCO /V A , 71±5); and MVV (62±5). Residual volume (RV), RV/total lung capacity (TLC), V E , and REE were elevated. Other lung volumes were normal. Thus, obese children have altered pulmonary function, which is characterized by reductions in D LCO and ventilatory muscle endurance and airway narrowing. These alterations may reflect extrinsic mechanical compression on the lung and thorax, and/or intrinsic changes within the lung. The reduced D LCO may result from decreases in alevolar surface area relative to lung volume. Pediatr Pulmonol. 1993; 16:130–137. © 1993 Wiley‐Liss, Inc.