Thoracic dimensions at maximum lung inflation in normal subjects and in patients with obstructive and restrictive lung diseases

Objectives: To compare the distribution of lung volume at total lung capaci ty (TLC) among adult men and women known to have normal lung function or ch ronic obstructive disease or restrictive lung disease (RLD). Design: Five-year retrospective study. Setting: Review of available clinical pulmonary function testing (PFT) repo rts and chest radiographs. Patients: Sixty-four patients presenting with normal PFT and chest radiogra ph findings (normal subjects), 26 patients with severe COPD and increased T LC (COPD group), 29 patients with cystic fibrosis (CF) and increased TLC (C F group), and 19 patients with RLD with a clinical diagnosis of pulmonary f ibrosis and a reduced TL (RLD group). Measurements: Average posteroanterior rib cage diameter (PAave), average la teral rib cage diameter (LAave), and average vertical height of the diaphra gm (HDIave) were measured using radiography. Normal prediction equations we re generated based on stature, body mass index (BMI), age, and sex as indep endent variables and then used in between-group comparisons. Results: PAave correlated positively with BMI and age but not with height, whereas LAave correlated positively with BMI and height but not with age. H DIave correlated positively with height and age but negatively with BMI. PA ave and LAave were smaller and HDIave was greater in women than men having the same stature. In the COPD group and in male CF group patients, BMI was low and only HDIave was greater than in sex-, age-, and height-matched norm al subjects, but in female CF group patients, only the rib cage diameters w ere greater than normal. In the RLD group, PAave and HDIave were smaller th an predicted and inversely related to each other, but LAave was normal. Conclusion: Variations in maximum lung volume caused by gender, growth, or by lung diseases are nonisotropic and entail substantial changes in chest w all shape.