Measurement of Pulmonary Edema

Pulmonary extravascular fluid volume (PEV) has been estimated by using a double isotope technique in nine normal subjects and 45 patients with valvular heart disease. The method was reproducible, the standard deviation being + 15.2 ml/m2, or 11.2% of the mean. Groups of patients with aortic and mitral valve disease had significantly higher values of PEV than normal persons; some patients with pulmonary stenosis had subnormal values. There was a relationship between PEV and the severity of dyspnea; all patients with an abnormally high PEV were class IL or worse. Of the 18 patients with abnormally high PEV, only seven had radiological evidence of chronic pulmonary edema. PEV was independent of blood flow but was clearly related to the level of pulmonary intravascular pressure. PEV was only significantly elevated if left atrial mean pressure exceeded 12 mm Hg and was invariably raised if it exceeded 25 mm Hg. No relationship of PEV to pulmonary vascular resistance was evident in this study.