Heparin management during cardiac surgery with respect to various blood-conservation techniques.

BACKGROUND

Various methods to reduce blood consumption are used in cardiac surgery. This study was designed to investigate the influence of various blood-conservation techniques on heparin plasma levels and coagulation variables in the perioperative period.

METHODS

Anticoagulation was achieved by application of 300 units/kg bovine heparin before cardiopulmonary bypass (CPB). Ninety patients undergoing coronary bypass surgery were randomly divided into six groups according to different blood-conservation methods: group 1, blood during and after CPB was concentrated by a cell saver (CS); group 2, blood was concentrated by means of a hemofiltration device (HF); group 3, acute normovolemic hemodilution (ANH) was performed in combination with the CS technique (ANH-CS); group 4, ANH was carried out in combination with an HF during CPB (ANH-HF); group 5, acute plasmapheresis (APP) was performed and a CS was used during CPB (APP-CS); and group 6, APP was used in combination with an HF device (APP-HF).

RESULTS

Heparin plasma concentration during CPB did not differ significantly among the six groups, ranging from 1.60 to 2.03 units/ml. Antagonization with protamine sulfate after termination of bypass in a 1:1 ratio decreased heparin concentration almost to baseline values. Fibrinogen concentration and antithrombin-III level were lowest in the CS group but were not decreased critically during the entire investigation period. Activated clotting time differed widely among the patients (range 383 to 807 seconds) and showed no significant correlation to heparin plasma levels. Partial thromboplastin time was higher than 300 seconds during the entire period of CPB, also indicating sufficient anticoagulation. Blood loss until day 1 after surgery was significantly most pronounced in the CS group and least in the APP-HF group.

CONCLUSIONS

The blood conservation techniques used in this study were safe with regard to sufficient anticoagulation during CPB. No insufficient antagonization with protamine could be observed in the postbypass period.