The Relationship Between Anthropometric Measures, Blood Gases, and Lung Function in Morbidly Obese White Subjects

Background Obesity may cause adverse effects on the respiratory system. The main purpose of this study was to investigate how various measures of obesity are related to arterial blood gases and pulmonary function. Methods This is a cross-sectional study of consecutive morbidly obese patients with normal lung function. Blood gas samples were taken from the radial artery after 5 min of rest with subjects sitting upright. Lung function measurements included dynamic spirometry, static lung volumes, and gas diffusing capacity. Results The 149 patients (77% women) had a mean (SD) age of 43 years (11 years) and BMI of 45.0 kg/m 2 (6.3 kg/m 2 ). The mean expiratory reserve volume (ERV) was less than half (49%) of predicted value, whilst most other lung function values were within predicted range. Forty-two patients had an abnormally low pO2 value (6.0 kPa [45 mmHg]). All anthropometric measures correlated significantly with decreasing pO2 and increasing pCO2 (all P values