Determination of pulmonary blood volume by injection into pulmonary artery and sampling in left atrium.

Dye dilution technique for measunrng pulmona blood volume is usually done by successive injectiot of the indicator into the pulmonary artery and ti left atrium and sampling in the brachial artery. Pu monary blood volume is measured as the product 4 the pulmonary mean transit time and cardiac ou put. Whether an indicator, which is injected in the pulmonary artery, can be sampled from the le atrium without any preferential sampling from or of the pulmonary veins is not certain. There is als doubt as to whether an indicator would be thorougl ly mixed without passing through a cardiac chamb4 (Dock et al., 1961). Levinson, Frank, and Heller (1964) have reported the measurement ofpulmonar blood volume by injection of indocyanine green dy into the pulmonary artery and sampling in the le atrium. Samet et al. (1966) have emined th accuracy of pulmonary artery injection-left atri. sampling curves, and have concluded that this tecd nique grossly overestimates the pulmonary bloo volume. Milnor and Jose (1960) have indicate that dye dilution curves, when recorded by samplin through cardiac catheters, are distorted due to th large volume of the sampling system. The presen investigation was conducted to assess the accurac of measuring the pulmonary blood volume by injec tion into the pulmonary artery and sampling in lef atrium after correction of the indicator dilutio: curve for volume: flow ratio of the sampling system according to Milnor's formula.