The ideal choice of a priming solution of the cardiopulmonary bypass (CPB) and its influence on the hemostatic system are not clear. Addition of albumin was reported to inhibit platelet damaging by blood-surface interactions ("coating"). To explore this possibility in 60 consecutive male patients undergoing elective aortocoronary bypass grafting, five different priming solutions were randomly used: (1) 1000 mL of 5% dextrose + 1000 mL of Ringer's solution (RS) + 250 mL of 5% human albumin (HA); (2) 1850 mL of RS + 400 mL of 20% HA; (3) 1750 mL of RS + 500 mL of 10% low molecular weight hydroxyethyl starch (molecular weight average: 200,000; molar substitution ratio: 0.5); (4) 1750 mL of RS + 500 mL of 3.5% gelatin; (5) 2250 mL of RS. Platelet function was studied by aggregometry (= turbidometric technique; 1.0 and 2.0-mu-mol/L of adenosine diphosphate (ADP), 4-mu-L/mL of collagen, 25-mu-mol/L of epinephrine) before, during, and after CPB until the first postoperative day. Blood loss and need for homologous blood was not different between the groups. During CPB, maximum platelet aggregation induced by ADP was least compromised in group 1 and group 4. At the end of the operation ADP-induced aggregation increased in group 1 (+27%), whereas aggregation was decreased in the other priming solution groups. A significant increase in maximum aggregation was found in group 1 even on the first postoperative day (+132% +/- 16%). Collagen-induced aggregation was also least compromised in group 1. Epinephrine-induced platelet aggregation did not change and was similar for all groups. Maximum gradient of aggregation was influenced in an identical way as maximum aggregation. We concluded that a priming solution consisting of dextrose, RS, and 250 mL of 5% HA was overall most effective in preserving platelet function. Addition of gelatin was not as effective for this purpose. Moreover, other aspects (e.g., material of the CPB, flow, temperature) appear to be more important with regard to platelet function than the choice of a prime solution.
