Activated Clotting Time, Anticoagulation, Use of Heparin, and Thrombin Activation during Extra-corporeal Circulation: Changes under Aprotinin Therapy

Abstract

In a prospective randomized double-blind study, the activated clotting time (ACT), heparin use, parameters of anticoagulation, and thrombin activation during extracorporeal circulation were studied in 20 patients who underwent aortocoronary bypass operations. The patients were divided into two groups: Group A was given a placebo, while Group B was given aprotinin according to the high-dosage Trasylol scheme. During ACT-controlled heparinization (ACT > 460 s) there was a significant heparin reduction in Group B (22,100 USP-E) in comparison to Group A (35,200 USP-E). Despite this lower quantity of total heparin, the ACT in Group B was significantly extended (Group B = 837 s, Group A = 492 s). The ACT did not correlate thereby with the heparin concentration or the total quantity of heparin in either group. In contrast to the control group, there was no increased thrombin generation in the aprotinin group. The thrombin-antithrombin III complexes (Group A = 143 micrograms/L, Group B = 102 micrograms/L) as well as the specific dimers (Group A = 2755 ng/ml, Group B = 448 ng/ml) were significantly lower under the use of aprotinin. The connection between the ACT, the heparin concentration, and the aprotinin concentration was further investigated in an ex-vivo model. The ACT samples were diluted with the aim of eliminating the influence of aprotinin. Under these conditions it was shown that for heparin concentrations between 2-4 U/ml there was a parallel shift of the ACT/heparinconcentration curve with the addition of aprotinin in a defined concentration range of 200-300 KIU.(ABSTRACT TRUNCATED AT 250 WORDS)

Anticoagulation Monitoring during Cardiac Surgery

“…209,210 When compared to an aprotinin concentration of 200 KIU/ml, the equipotent dose of heparin required to inhibit whole blood clotting time is 0.69 U/ml. 220 Although some researchers have suggested that aprotinin is a heparin-sparing agent, 221 Hunt et al 222 suggested that heparin doses be administered to maintain celite ACT values greater than 750 s when aprotinin is used. 89 Patients receive smaller heparin doses and have lesser blood heparin concentrations when heparin dosing is guided by celite ACT protocols during aprotinin administration.…”

Role of endogenous adenosine as a predictive marker of vasoplegia during cardiopulmonary bypass and postoperative severe systemic inflammatory response

“…Immediately after induction of anesthesia, patients were infused with 1 million inhibitor units of kallikrein. A further 1 million units was added to the CPB prime solution, and patients were continuously infused with 250,000 units/hr during surgery (16). During CPB, vasoplegia was considered to have occurred if the mean arterial pressure was Ͻ50 mm Hg, with a duration Ͼ5 mins despite a normal blood flow rate of 2.4·L·min Ϫ1 ·m Ϫ2 .…”

Adenosine A2A Receptor Hyperexpression in Patients with Severe SIRS after Cardiopulmonary Bypass

“…A further 1,000,000 U were added to the cardiopulmonary bypass prime solution, and patients were continuously infused with 250,000 U/hour during surgery. 23 During CPB, vasoplegia was considered to have occurred if the mean arterial pressure was less than 50 mm Hg with a duration of more than 5 minutes despite a normal blood flow rate of 2.4 LImin j1 Im j2 . 24 All patients had pacing wires placed but none of them required permanent pacing at the postoperative period.…”