Thromb Haemostasis
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The haemostatic system and the use of heparin during cardiopulmonary bypass (CPB) have been studied extensively in adults but not in children. Results from adult trials cannot be extrapolated to children because of age-dependent physiologic differences in haemostasis. We studied 22 consecutive paediatric patients who underwent CPB at The Hospital for Sick Children, Toronto. ⋯ However, low plasma concentrations of heparin (< 2.0 units/ml in 45% of patients) during CPB were likely a major contributing etiology. ACT values showed a poor correlation (r = 0.38) with heparin concentrations likely due to concurrent haemodilution of haemostatic factors, activation of haemostatic system, hypothermia and activation of platelets. In conclusion, CPB in paediatric patients causes global decreases of components of the coagulation and fibrinolytic systems, primarily by haemodilution and secondarily by consumption.
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Hypoxia and ischaemia influence blood coagulation and fibrinolysis. This study has been made to determine whether human cardiopulmonary arrest causes fibrin formation and reduction of fibrinolysis. Serial levels of fibrinopeptide A (FPA), fibrinopeptide B beta 15-42 (FPB beta 15-42), D-dimer, tissue plasminogen activator antigen concentration (t-PA antigen), t-PA activity, plasminogen activator inhibitor-1 antigen concentration (PAI-1 antigen), and PAI-1 activity were determined in 63 patients with out-of-hospital cardiopulmonary arrest. ⋯ At 24 h after admission, PAI-1 antigen and PAI-1 activity were significantly increased (472.2 +/- 145.5 ng/ml; p < 0.001 and 103.6 +/- 36.1 IU/ml; p < 0.001, respectively). In conclusion, during and after CPR in patients with out-of-hospital cardiac arrest, massive fibrin generation with consecutive impairment of fibrinolysis were observed. These fibrin-mediated events may have some role in the derangement of vital organ function after cardiac arrest.