MONITORING OF COAGULATION STATUS USING THROMBOELASTOGRAPHY DURING PEDIATRIC OPEN-HEART-SURGERY

Thrombelastography (TEG) has proved useful in identifying coagulopathies (via assessment of clot elasticity properties) during hepatic surgery, but its role in cardiac surgery has as yet not been defined. Twenty-two children [11M, 11F, mean age (range) 4.9 (0.1-16) years] undergoing open heart surgery were investigated [1] preoperatively, [2] 15 min post protamine, [3] 2 h and [4] 24 h postoperatively using TEG. Comparisons were made between pre- and postoperative measurements and haematological indices. The values obtained from the TEG were: R phase (indicative of thrombokinase and thrombin formation disorders), K phase (indicative of fibrinogenesis) and MA phase (providing information on clot stability and platelet function). The patients were divided into two groups based upon 24 h blood loss; Group 1 - blood loss < 0.7 ml/kg/h and Group 2 - blood loss > 0.7 ml/kg/h. In Group 2 there was a highly significant correlation between post-protamine MA phase and platelet number (r = 0.93, p < 0.001) but there was no correlation in Group 1 (p > 0.1). Furthermore, in Group 2 elevated postoperative blood loss was associated with a prolonged K phase (mean [SD] 12.0 [6.0] versus 6.3 [2.1] min, p < 0.05) and diminished MA phase (37 [12.5] versus 56 [4.9] mm, p < 0.01) relative to preoperative values. In Group 1, K and MA phase did not alter significantly (p > 0.5 and p > 0.2, respectively). TEG predicted with 100% (8/8) accuracy increased post-operative bleeding. The specificity of TEG prediction of future bleeding was 73% [8/11]. Alterations in TEG parameters merit further evaluation as markers of postoperative haemorrhage.