Reduction in Pulmonary Blood Volume after a Blood Loss

There is little information about the possible role of the pulmonary vascular bed as a variable blood depot. An evaluation of the degree of blood mobilization from this vascular compartment after a blood loss has therefore been attempted. Rats were given labelled erythrocytes and albumin, and immediately after a standardized blood loss the circulation was arrested by immersing the animals in liquid nitrogen. The lungs and tissue samples from liver and skeletal muscles were removed, and their blood contents evaluated. Values found in the tissues of the bled animals were compared with those from a group of non‐bled control animals. In a group of animals bled 12% of their total blood volume the mean pulmonary blood volume was reduced by 25%, while the muscle and liver blood contents were reduced by about 10% only. This difference was even more pronounced in a group of animals bled 24% of their total blood volume. The reduction in pulmonary blood volume was in the former group equal to 27% of the lost blood. This was more than the amount of blood contributed from the whole mass of skeletal muscle. In the bled animals the weight of the lung tissue proper was considerably reduced, indicating that there had been a reduction also in lung tissue water.