HIGH FLOW TOTAL BODY PERFUSION UTILIZING DILUTED PERFUSATE IN A LARGE PRIME SYSTEM.

SUMMARY Reduction of homologous blood requirements in high flow extracorporeal circulation has been accomplished by perfusate dilution up to 58 per cent of total volume in 135 cases. In the last 95 cases the basic diluent employed was a 5 per cent dextrose/Ringer's/albumin (DRA) solution. Perfusions were generally conducted at 20° to 30° C., with flow rates of 2.0 to 2.4 L. per square meter per minute. Three perfusates were employed: (a) 16 patients underwent open-heart surgery with 30 per cent of the priming volume consisting of DRA and the remainder fresh heparinized blood; (b) 51 patients were perfused with 34 per cent of the priming perfusate consisting of DRA (in addition, THAM was infused during cardiopulmonary bypass at a rate of 7 ml. per kilogram per hour of perfusion); (c) in 28 patients a perfusate consisting of equal volumes of ACD blood and diluent was used. In all cases the diluent comprised DRA and THAM. As in b, THAM was also administered during perfusion at the same rate described above. The average pump hematocrit in group c was 20.5. Immediate postperfusion overinfusion was required for all groups and reflected probable loss of diluent from the intravascular space. A moderate postperfusion metabolic acidosis was present in the DRA30 group but was absent in both THAM groups. All groups showed satisfactory blood pO2 and pCO2. Serum electrolytes (sodium, potassium, calcium, and chloride) were normal during and after perfusion in all groups. Rarely, a mild hypochloremia was observed on the first postoperative day. Pulmonary and metabolic complications have been less than in a comparative series of patients operated upon with whole blood. Hemodilution (30 to 58 per cent) has been well tolerated and significantly reduces blood requirements. It is currently our practice to perform open-heart surgery on all patients over 30 kilograms with 50 per cent hemodilution and buffered ACD blood. It is probable that the high flow rates achieved compensate for the initially reduced oxygen-carrying capacity of the diluted blood.