Platelet count and function in paediatric cardiac surgery: a prospective observational study.

BACKGROUND Platelet deficiency, impaired platelet function, or both increase the risk of bleeding complications. We assessed platelet count and function during and after paediatric cardiac surgery. Secondary aims included the effect of modified ultrafiltration, identification of factors associated with platelet dysfunction, and to assess associations between platelet function and transfusion requirements. METHODS Fifty-seven patients were included in a prospective observational study. Platelet count and platelet function (multiple-electrode impedance aggregometry) were analysed before and during cardiopulmonary bypass (CPB), after modified ultrafiltration, on arrival at the intensive care unit, and on the first postoperative day. Intraoperative transfusions of blood products were registered. RESULTS Both platelet count and platelet aggregation were markedly reduced during surgery with the greatest reduction at the end of CPB. On postoperative day 1, platelet count was still reduced by 50%, while platelet aggregation had returned to-or above-preoperative levels. There were only moderate correlations between platelet count and platelet aggregation. Modified ultrafiltration had no significant influence on platelet count or aggregation. Young age, low weight, and long operation time were associated with poor platelet aggregation during surgery, while young age, low weight, high preoperative haemoglobin levels, and low preoperative platelet count were associated with poor aggregation after operation. Patients with impaired platelet function during CPB had markedly increased intraoperative transfusion requirements. CONCLUSIONS Platelet count and platelet aggregation are markedly reduced during and immediately after paediatric cardiac surgery, especially in neonates. The recovery in aggregation is faster than that in platelet count. Intraoperative platelet dysfunction is associated with increased transfusion requirements.