Preparation for regional anaesthesia induces changes in thrombelastography

The effects of crystalloid and colloid infusions on coagulation measured by thrombelastography (TEG) present a confused picture. The influence of envi ronmental factors may explain the disparity between previous studies. We st udied two groups of 20 women presenting at term for elective Caesarean sect ion. In the first group, TEG analysis was performed before and after infusi on of Gelofusine 500 ml over 15 min. The second group was treated in the sa me way except that subjects did not receive fluid. We found significant cha nges in r and k values in both groups, suggesting enhanced coagulation. As hypercoagulable changes were also seen in the group that did not receive fl uid preload, the hypothesis that moderate haemodilution causes hypercoagula bility must be questioned. The influence of environmental factors can expla in differences reported between in vivo and in vitro studies.