Effects of BMI on static lung volumes in patients with airway obstruction
Denis E O'Donnell1, Athavudh Deesomchok1, Yuk-Miu Lam2
1Department of Medicine, Queen's University and Kingston General Hospital, Kingston, ON, Canada.
Background:
Both chronic airway obstruction and obesity are increasing in prevalence but the effect of their combination on pulmonary function parameters across the range of airway obstruction is unknown.
Methods:
We studied the impact of increasing BMI on static lung volumes and airway function in a cohort of 2,265 subjects from a large pulmonary function laboratory database who were 40 to 80 years of age and met GOLD (Global Initiative for Chronic Obstructive Lung Disease) spirometric criteria for COPD (postbronchodilator FEV₁/FVC < 0.7). We also evaluated the influence of severity of airway obstruction (by GOLD criteria) on these relationships.
Results:
With increasing BMI in the group as a whole, functional residual capacity, residual volume, expiratory reserve volume, and specific airway resistance (sRaw) decreased exponentially (all P < .001); total lung capacity (TLC) decreased linearly (P < .001); and inspiratory capacity (IC) and IC/TLC increased linearly (P < .001). However, vital capacity was not influenced significantly. The effects of increasing BMI on FEV₁/FVC and sRaw were greatest in GOLD stage III/IV (P < .05), whereas increasing BMI had greater effects on IC in GOLD stage I (P < .001).
Conclusions:
With increasing BMI, subjects with airway obstruction had consistent reductions in lung hyperinflation, with significant improvements in IC and the FEV₁/FVC ratio; this effect was greatest in patients with the most severe airway obstruction. These results have important implications for the clinical assessment of patients with combined obesity and airway obstruction.
Related Concept Videos
Respiratory Volumes
Tidal Volume (TV) Tidal volume (TV) is the air inhaled or exhaled in a...
Factors Affecting Pulmonary Ventilation
Alveolar Surface Tension
The alveolar fluid lines the luminal surface of the alveoli and exerts a force called surface tension. This force is caused by the polar water molecules in the liquid being more strongly attracted to each...
Chronic Obstructive Pulmonary Disease III: Chronic Bronchitis Features
Assessment of Airway, Skin Color, and Use of Accessory Muscles
Introduction
The initial evaluation of a patient's respiratory system...
Pressure Relationships in Thoracic Cavity
Breathing Mechanisms
Both intra-alveolar and intrapleural pressures rely on specific lung properties. The ability to breathe—allowing air to enter the lungs during...
Chronic Obstructive Pulmonary Disease-IV: Assessement and Diagnostic Studies
Medical History

