Blood volume and haemodilution in extracorporeal circulation: changes during perfusion

An adequate circulating blood volume is recog-nized to be important after open-heart surgery (Carr, Sloan, and Tovar, 1960). A number of post-operative studies have attempted to correlate clinical determinations of blood loss with volumes estimated by tracer techniques. Discrepancies noted have been attributed to extensive haemor-rhage into traumatized tissue (Flanagan, Stein-metz, Crawford, and Merendino, 1964), internal redistribution of functional extracellular fluid by plasma exudation occurring after any form of major surgery (Berger, Boyd, and Marcus, 1964), or to the homologous blood syndrome, in which there is a shift of blood from the extracorporeal circuit into the patient during perfusion and a measurable blood deficit post-operatively (Gad