Postoperative heparin rebound was investigated in 50 adult patients undergoing cardiopulmonary bypass with the use of the Hepcon heparin analyzer. Prior to bypass each patient received 2 mg/kg of heparin. During bypass, the activated clotting time (ACT) was utilized to assess the need for additional heparin to maintain the value between 300 and 400 seconds. The average amount of heparin given was 160 mg. Once cardiopulmonary bypass was terminated the Hepcon unit was employed to determine the actual amount of active circulating heparin and to calculate the dose of protamine sulfate. The average amount of protamine administered intraoperatively was 200 mg. The overall mean ratio of protamine-to-heparin was 1.25 : 1. Once hemostasis was achieved, no circulating heparin was measured with the Hepcon unit, and the ACT value had returned to its baseline, the incisions were closed and the patients were transferred to the intensive care unit. One hour later a blood sample was obtained and analyzed by the Hepcon unit for any heparin rebound. We found that 26 patients (52%) had circulating heparin and required an additional dose of protamine, averaging 70 mg. Drainage from the thoracotomy tubes averaged 400 cc in the first 24 hours, and a mean of 2 units of packed cells was infused. Three patients (6%) did not require any blood transfusions. The use of the Hepcon unit has produced a safe and expedient method of analyzing and neutralizing active circulating heparin in patients following cardiopulmonary bypass. It is a useful adjunct in blood conservation because it reduces excessive postoperative blood loss associated with heparin rebound.

Ninety-six patients were studied to determine the role of immediate centrifugation of oxygenator contents and retransfusion as packed cells after cardiopulmonary bypass. The patients were studied in three phases: Group I comprised 16 patients. Safety, sterility, effectiveness of red cell concentration, hemolysis, heparin levels, and electrolyte balance were studied. Group II comprised 50 patients, 25 each in a control group (IIA) and study group (IIB). Group HA patients had retransfusion of dilute oxygenator contents in whatever volume tolerated; Group IIB patients had centrifugation of oxygenator contents, without use of other methods of blood conservation. In Group III, comprising 30 patients, centrifugation was combined with other methods of blood conservation. In 15 patients of Group IIIA, prebleeding autotransfusion was not used, whereas it was used in 15 patients of Group IIIB. Centrifugation of oxygenator contents was found to be safe, sterile, and effective in concentrating red cells without damage. Electrolyte and heparin reinfusion are diminished by approximately 86 percent. Postoperative bleeding is diminished by 33 percent with centrifugation alone (Group IIB) and by 61 percent with centrifugation in addition to use of maximum blood conservation plus autotransfusion (Group IIIB). Bank blood transfusion is diminished by 25 percent with centrifugation in Group IIB, by 43 percent in Group IIIA, and by 77 percent in Group IIIB. Blood centrifugation plays an important role in blood conservation and also serves as a means of minimizing the consequences of fluid overload after cardiopulmonary bypass.

Sixty patients undergoing cardiopulmonary bypass (CPB) with the Travenol 6 L. variflow oxygenator bag and total hemodilution with Ringer's lactate with 5 per cent dextrose were observed for their variances in potassium (K+) levels and the degree of potassium replacement. We have seen that the potassium level drops before CPB bypass in relation to the preadmission to the operating room potassium level. During bypass the level rises and following bypass it once again falls to be preceded by a rise after the first 24 hour postoperative period...

Two protocols of heparin management during cardiopulmonary bypass were compared to assess the role of the activated clotting time (ACT) in relation to postoperative blood loss. The study was divided into two groups: Group I, the control group, in which 3 mg. of heparin per kilogram was given as the initial dose and maintained at a dose of 1.5 mg. per kilogram every 45 minutes during cardiopulmonary bypass, and Group II, in which the initail dose of heparin was 2 mg. per kilogram and additional dosage were based upon the ACT. We found a striking decrease in postoperative blood loss as well as a decrease in the amount of heparin administered during cardiopulmonary during cardiopulmonary bypass in Group II patients. In addition, less protamine was required to neutralize the heparin in the second group after bypass. Thus, when patients are given too much heparin, as in our control group, the effectiveness of protamine is decreased. We would like to stress the value of the ACT in controlling heparin administration as well as postoperative blood loss in cardiopulmonary bypass surgery.