Effect of epsilon-aminocaproic acid on fibrinolysis in patients undergoing open heart surgery with cardioulmonary bypass / 中华麻醉学杂志

ABSTRACT

Objective To investigate the dynamic changes in the fibrinolytic system during and after open heart surgery performed with cardiopulmonary bypass (CPB) and the effect of epsilon-aminocaproic acid (EACA) on fibrinolysis, postoperative blood loss and transfusion requirements.Methods Forty patients (24 males, 16 females) aged 17-43 yr undergoing valve replacement with CPB were randomized to receive EACA 200 mg?kg-1 (group A) or normal saline (group B) added to the priming solution. The patients were premedicated with intramuscular morphine 0.2 mg?kg-1 and scopolamine 0.3 mg. Anesthesia was induced with midazolam 0.2 mg ? kg, fentanyl 10 ?g?kg-1 and vecuronium 0.1 mg?kg-1 and maintained with isoflurane inhalation and intermittent i.v. boluses of fentanyl and vecuronium. The patients were mechanically ventilated (VT = 10 ml?kg-1 , RR = 10-12 bpm, IE = 12) after tracheal intubation. Blood samples were taken before skin incision (baseline) , 8 and 30 min on CPB, 10 min after protamine administration and 2 h after operation for determination of tissue type plasminogen activator (t-PA) activity, plasminogen activator inhibitor (PAI) activity, plasmin (Plm) activity and D-dimer. The amount of blood drained from chest and bank blood infused within 24 h after operation were recorded.Results (1) Group B (control group) PAI activity was maintained stable perioperatively. The t-PA activity and t-PA/PAI ratio increased significantly during operation but returned to the baseline value 2 h after operation. D-dimer level also significantly increased during and after operation. The Plm activity increased significantly at 8h on CPB and 10 min after protamine administration compared to the baseline value. (2) The t-PA activity and t-PA /PAI ratio were significantly lower in group A than in group B. The D-dimer level and Plm activity were also significantly lower in group A than in group B during and after operation. The amount of blood loss and bank blood infused within 24 h after operation was 40% and 37% less than that in group B.Conclusion Fibrinolytic system is activated during CPB as shown by the increase in plasminogen and t-PA/PAI ratio. EACA is effective in reducing postoperative blood loss and blood transfusion through inhibition of the activation of fibrinolytic system.