Transpulmonary pressure at full inspiration and and dynamics of the airways in patients with obstructive lung disease.

In a group of 187 patients with various types of obstructive lung disease, the transpulmonary pressure at full inspiration (Ptlc) was correlated with other lung function variables and with symptoms. Measurements were made before and after bronchodilation. In a number of patients, the effect of bronchoconstriction on the volume-pressure curves was assessed. As estimated from the Ptlc, the lungs were abnormally compliant in most patients. This abnormality was most pronounced in the younger subjects, in whom reduced elastic recoil occurred without signs of airway obstruction during forced expiration and without increased total lung capacity. The findings suggested that lung structures determining elastic recoil were at least partly independent of those determining mechanical stability of the airways. Statistical analysis revealed that the clinical value of Ptlc measurement was limited to the differentiation of patients with asthma from those with emphysema. Because these subjects constituted less than 10 per...