Evaluation of Tourniquet Effects on Coagulation during Knee Arthroscopy

Background: Tissue trauma, pain and surgical stress can increase coagulability in perioperative period. Tourniquet application can increase DVT by blood stasis and releasing tromboxane, but some studies concluded that tourniquet will increase fibrinolysis. In this study, the changes in coagulability and fibrinolysis due to tourniquet application were evaluated by thrombelastograph during knee arthroscopy. Methods: In this clinical trial, 30 patients without known risk factors of coagulopathies were studied. Blood sampling were done immediately before tourniquet inflation (TI) as well as 2 and 30 minutes after tourniquet deflation (TD). Thrombelasthographic parameters including R-time, K-time, α angle, MA, LY30 and LY60 were measured and analyzed by t-paired test and ANOVA in SPSS software. Findings: The mean of R-time at 2 and 30 minutes after TD decreased and the mean of α increased in comparison with before TI (p<0.0001). The mean of MA at 2 and 30 minutes after TD increased first and then decreased and LY30 decreased first and then increased in comparison to before TI (p, 0.001). Conclusion: Tourniquet application initially can increase coagulability and the probability of thrombus formation after TD, but after a short time, compensatory clot lysis occurs by increasing fibrinolytic activities. Keywords: Coagulation, fibrinolysis, thrombelastograph, tourniquet