Objective: The effect of aprotinin administration during extracorporeal circulation in pediatric patients is controversial and its mechanism of action is not well known. The objective of this study was to evaluate in children the effect of high doses of aprotinin administered during cardiac surgery with cardiopulmonary bypass on bleeding and on hemostasis.

Methods: 31 patients (age range 1-15 years) undergoing cardiac surgery were included. 17 of them received treatment with aprotinin (240 mg/m2 in bolus followed by 50 mg/m2/h) and 14 were controls. Bleeding was measured during surgery and at 6, 12, and 24 hours post-surgery. Samples to study hemostasis parameters were obtained pre-surgery, after 30 min in cardiopulmonary bypass, at the end of cardiopulmonary bypass and at the end of surgery. Platelet expression of P-selectin and platelet glycoproteins IIb-IIIa and Ib were measured by flow cytometry. Plasmatic content of prothrombin fragment 1+2 (F1+2), plasmin-α2-antiplasmin complexes (PAP), and fibrin-fibrinogen split products (FbFgDP) were quantified by ELISA.

Results: Intraoperative bleeding was significantly lower in the aprotinin-treated patients than in the control group (p<0.05). Bleeding observed at 6, 12, and 24 hours post-surgery were also lower in the aprotinin-treated group (p<0.01). P-selectin expression increased during surgery in comparison to basal samples (p<0.05), but no significant changes were observed in IIb-IIIa or Ib. P-selectin and platelet glycoproteins expression were not significantly different between both groups. F1+2, PAP, and FbFgDP increased during cardiopulmonary bypass and decreased at the end of surgery. In the samples obtained during surgery F1+2, PAP, and FbFgDP values were higher in controls than in the aprotinin-treated patients(p<0.001).

Conclusions: In children undergoing cardiac surgery aprotinin reduces bleeding during and immediately after surgery. This effect may be due to a lower hemostatic impairment that seems more related to the inhibition of thrombin generation and plasma fibrinolysis than to changes in platelet activation.