SURGICAL TOURNIQUET PAIN ACCELERATES BLOOD COAGULABILITY BUT NOT FIBRINOLYSIS/

Tissue damage during surgery induces coagulation factors and activates platelets. Surgical pain may provoke release of catecholamines, leadi ng to hypercoagulability. We have investigated the effect of surgical pain on blood coagulability and fibrinolysis in orthopaedic operations using tourniquets in 22 patients undergoing total knee replacement. P atients were allocated to one of two groups to receive extradural anae sthesia (EA; n=11) or general anaesthesia (GA; n=11). The EA group rec eived lumbar extradural block with lidocaine. The GA group received on ly general anaesthesis, maintained with 1.5-2.5% sevoflurane and 66% n itrous oxide in oxygen. Using a thrombelastogram technique, blood coag ulability and fibrinolysis were measured. Mean maximum amplitude (MA), which reflects coagulability, increased after tourniquet inflation (1 1%) in group GA whereas MA in group EA did not change. After tournique t deflation, MA values in both GA and EA groups increased significantl y (10% and 20%, respectively) (P<0.05), and there was also a significa nt difference in MA between groups (P<0.05). The fibrinolytic rate did not change in either group during tourniquet inflation, but increased significantly (160%) after tourniquet deflation. There was no signifi cant difference in fibrinolytic rate between the groups. We conclude t hat the hypercoagulability seen in group GA could have been caused by surgical or tourniquet pain, or both, and that extradural anaesthesia is a useful technique to prevent hypercoagulability.