The priming of extracorporeal circuits: the effect on canine blood elements.

Improving hemocompatibility is of major interest in extracorporeal circulation (ECC). Changes in numbers and functions of the blood cells during ECC have been ascribed to the nonphysiologic materials of the circuit. In this study, commonly used priming fluids (banked blood, Ringer's lactated solution, gelatin solution and dextran 70 solution) have been investigated for their influence on numbers and functions of canine thrombocytes, leukocytes and erythrocytes. Infusion of banked blood and Ringer's lactated solution did not affect number and function of the thrombocytes, whereas the plasma expanders caused dramatic, but reversible decreases. Leukocyte numbers were also affected, but only gelatin resulted in a decrease of leukocyte function. No effect on erythrocyte numbers was observed. It is concluded that under these experimental circumstances some priming solutions cause acute intravascular aggregation. To obtain the optimal condition for studying the hemocompatibility of ECC, preferably Ringer's lactated solution should be used.