CHILD HEALTH SERIES The effects of obesity on pulmonary function

Aims: (1) To determine the predominant pulmonary function abnormality in our population of obese children; and (2) to assess the correlation between the severity of lung function impairment and the degree of obesity as assessed by dual energy x ray absorptiometry (DEXA). Methods: Sixty four obese patients underwent physical examination, standardised pulmonary function tests (spirometry, lung volumes, and single breath diffusion capacity for carbon monoxide), and DEXA scan measurements. The trunk and subtotal (total − head) body fat mass were used as surrogate index of body adiposity. Results: Sixteen girls and 48 boys with median age and body mass index (BMI) of 12 years (interquartile range (IQR): 10–14) and 30.1 kg/m2 (IQR: 27.2–32.8) respectively were studied. None of the patients had clinical evidence of cardiopulmonary disease. Reduction in functional residual capacity (median FRC 93 % predicted, IQR: 68.5–116.5%) and impairment of diffusion capacity (median DLco 83.5 % predicted, IQR: 70.0–100.7%) were the most common abnormalities in our cohort, being observed in 30 (46%) and 21 (33%) patients respectively. Obstructive ventilatory impair-ment was found in three patients. There was significant negative correlation between the degree of reduction of FRC but not DLco with DEXA scan measurements, but such a relation was not found whe