Determination of Pulmonary Blood Volume by Single Intravenous Injection of One Indicator in Patients with Normal and High Pulmonary Vascular Pressures.

are based on the Stewart-Hamilton principle. Different types of indicators (dyes and radioisotopes) are used, and their varying concentrations are determined either from arterial sampled blood 1, 2 or by precordial scanning.3-9 Combined right and left heart catheterization provides a more direct measurement of pulmonary blood volume in man, by the indicator-dilution technic. In methods already described,1 2 the pulmonary artery and the left atrium are used as sites of injection of the indicators, sampling being made in a peripheral artery. Milnor, Jose, and McCaff1 use one indicator, which is injected successively in the pulmonary artery and left atrium, or vice versa, whereas the technic of Dock et al.2 requires the simultaneous delivery into the circulation of two indicators, one for each injection site. The purpose of this paper is to report and discuss the results obtained with a technic that does not require two indicators or two successive injections of the same indicator, but substitutes peripheral arterial sampling for central sampling (pulmonary artery and left atrium), dye being injected near the right atrium.