Pulmonary Function in Obesity

Abstract

A 70-year-old obese patient (BMI 63.2 kg/mβ) presents with dyspnea. Pulmonary function tests show a restrictive pattern with reduced forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), total lung capacity (TLC), and functional residual capacity (FRC), but a normal FEV₁/FVC ratio and residual volume (RV). The lung diffusing capacity for carbon monoxide (DLCO) is significantly reduced, but the DLCO/VA ratio is normal. These findings are consistent with a restrictive process related to marked obesity, which often results in reduced TLC and FRC due to decreased chest wall compliance. The normal DLCO/VA suggests a non-parenchymal disorder, possibly due to increased pulmonary blood volume. Obesity-related changes in lung function, including reduced expiratory reserve volume (ERV), are discussed.