Thromboelastographic study of the effect of manipulation of central veins on coagulability of venous blood

Aim: To measure whole blood coagulability in vitro using thromboelastography before and after direct and indirect manipulation of the internal jugular and subclavian veins. Methods: We studied 10 patients (American Society of Anaesthesiologists (ASA) grades I or II) with malignant disease of the head and neck who were having selective neck dissections. We excluded patients with diabetes, those who were being given any anticoagulant, those who were actively infected, and those with known coagulopathy. We took 3 ml samples of venous blood during insertion of a peripheral cannula, after insertion of a central venous cannula, and after dissection of the internal jugular vein. Thromboelastography was done on recalcified citrated samples within 1 h of sampling. The variables r, k, α angle, and maximum amplitude were recorded at each point and the values before and after manipulation were compared using t-tests. Results: The only change was seen in the variable r, which showed an insignificant increase in coagulability.