CHANGES IN BRAIN PH, PO2, PCO2, CEREBRAL BLOOD-FLOW, AND BLOOD CASES INDUCED BY A HYPEROSMOLAR OXYREPLETE HEMOSUBSTITUTE DURING CARDIOPULMONARY BYPASS

Eleven goats (mean weight, 69 +/- 16 kg) underwent 5 hrs of normotherm ic nonpulsatile cardiopulmonary bypass (CPB) using as priming fluid ei ther a Ringer's based crystalloid priming solution (CP, n = 5) or a hy perosmolar oxyreplete hemosubstitute (HS, n = 6). The HS contained 20% w/v of perfluorocarbon bon (perfluorodecalin), its osmolarity was 800 -900 mOsm/1, and the administered dose of perfluorocarbon was 30-50 ml /kg. Otherwise, the experimental procedure was identical for both grou ps. PaCO2 was maintained above 35 mmHg and blood flow rate at 65 ml/mi n/kg. Brain tissue pH, PO2, and PCO2, cerebral blood flow (CBF), arter ial and venous blood gases, and other systemic Variables were monitore d. During CPB, PvO2 and brain tissue PO2 were increased significantly in the HS group. The CBF per kilogram of weight also was significantly higher in the HS group. Metabolic acidosis developed in both groups a nd, surprisingly, brain tissue pH and pH, were lower in the HS group. The mean values of PvCO2 and brain tissue PCO2 indicate that brain tis sue hypercapnia also occurred in both groups. The HS provided long-ter m stability and compatibility with electrolytes, and did not cause maj or complications or allergic reactions during CPB. Perfluorocarbon bas ed HSs improve tissue oxygenation, eliminate the risk of infection due to homologous transfusions, do not require blood type matching, have a shelf life longer than that of blood, and, therefore, they can be an important factor in diminishing the incidence of complications after CPR.