The effects of obesity on pulmonary function
1Department of Paediatrics, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong SAR. albertmli@cuhk.edu.hk
Insights
Obese children commonly show reduced lung volumes and impaired diffusion capacity. Lung function decline correlated with obesity measured by DEXA, not BMI.
Area of Science:
- Pediatric Pulmonology
- Obesity Research
- Diagnostic Imaging
Background:
- Childhood obesity is a growing public health concern.
- Obesity can impact respiratory health, but specific pulmonary function abnormalities require elucidation.
- Dual-energy X-ray absorptiometry (DEXA) offers a precise measure of body composition.
Purpose of the Study:
- To identify prevalent pulmonary function abnormalities in obese children.
- To investigate the relationship between obesity severity (using DEXA) and lung function impairment.
Main Methods:
- Sixty-four obese children underwent spirometry, lung volume measurements, and diffusion capacity tests.
- Body composition was assessed using DEXA scans, with trunk and subtotal fat mass as obesity indicators.
- Standard physical examinations were performed.
Main Results:
- Reduced functional residual capacity (FRC) in 46% and impaired diffusion capacity (DLco) in 33% were the most common findings.
- Obstructive ventilatory defects were observed in 3 patients.
- A significant negative correlation existed between reduced FRC and DEXA-measured adiposity, but not with BMI.
Conclusions:
- Reduced static lung volumes (FRC) and diffusion capacity are common in obese children.
- The degree of obesity, as measured by DEXA, correlated with reduced static lung volumes, highlighting the impact of adiposity on respiratory mechanics.
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 impairment 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 when BMI was used as the indicator of obesity.
Conclusion:
Reduction in FRC and diffusion impairment were the commonest abnormalities found in our cohort of obese patients. Reduction in static lung volume was correlated with the degree of obesity.
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