Haemostatic changes during open heart surgery with extracorporeal circulation and deep hypothermia in children

The haemostatic status of twenty children with cyanotic and acyanotic cardiopathies was studied before, during and after cardiopulmonary bypass (CPB) under deep hypothermia and haemodilution. Eleven patients had various haemostatic troubles before surgery. Haemodilution with a crystalloid solution to an haematocrit of 21,8 vol. +/- 1,3% resulted in a severe lowering of all coagulation factors. Forced diuresis after CPB induced partial normalization. The observed alterations included moderate thrombocytopenia, prolongation of the prothrombin time, transient decrease of factors V and plasminogen, elevation of fibrin degradation products (FDP), significant lowering of factor VII-X, marked elevation of factor VIII and mild increase of fibrinogen. No correlation was found between coagulation abnormalities and postoperative bleeding, duration of CPB or type of cardiopathies. It is concluded that CPB with haemodilution proves as safe as more conventional approaches in respect to coagulant activities.