Tissue extravasation of albumin from intraabdominal trauma in rats

Intraabdominal surgery tends to lower circulating plasma volume by mechanisms unrelated to bleeding and evaporation. In chloralose-anesthetized rats, the tissue clearance of radiolabelled albumin was determined by a double isotope method. Animals were subjected to a standardized abdominal trauma, eliciting minimal bleeding and evaporation, and others served as controls. The trauma significantly increased tissue albumin extravasation in abdominal skin, abdominal wall, pancreas, small intestine, colon, mesentery and diaphragm. Considering the mass of the respective tissues, a substantial portion of the albumin extravasation took place in the abdominal wall. No increased albumin clearance was found in extra-abdominal tissues. It is suggested that abdominal surgery decreases plasma volume by extravasation in the operation field.