Effect of acute hemorrhage on the calculated lung hematocrit

The hematocrit for the lesser circulation was determined in 22 dogs using Cr51-tagged cells and either indocyanine green or radioactive serum albumin as the plasma tag. To assess the variation due to methodology, a reproducibility study alone was done in 8 dogs, and in 14 dogs measurements were made before and after the blood pressure was lowered to 50 mm Hg by acute hemorrhage. The lung hematocrit was obtained both from the cell and plasma volume measured by the indicator dilution technique and by the ratio of the mean circulation times. There was no significant difference between the calculated lung hematocrit and the peripheral hematocrit in the control state or following hemorrhage.