Low-frequency hemoviscoelastography: a new method of diagnostics for coagulation disorders after abdominal surgery for cancer

Background

Venous thromboembolism is one of the most common complications seen in cancer patients and may be due to the hypercoagulable state of the malignancy and to its surgical treatment. Despite clinical and laboratory evidence of perioperative hypercoagulability, there are no consistent data evaluating the extent, duration, and specific contribution of platelets and procoagulatory proteins by in vitro testing.

Materials and methods

Patients undergoing planned curative open surgery for abdominal cancer received MEDNORD (Ukraine Co analyser) analysis (HVG), a viscoelastic test that measures clot formation and includes information on the cellular, as well as the plasmatic coagulation, system. We examined the efficacy of a variety of coagulation tests. A complete coagulation screen, activated clotting time, thromboelastography (TEG) and hemoviscoelastography (HVG) were performed before surgery, at the end of surgery, and on postoperative days 1, 2, 3, and 7; they were analyzed for the reaction time and the maximal amplitude (MA). We tested the hypothesis that the parallel use of standard TEG and HVG can assess postoperative hypercoagulability and can estimate the independent contribution of procoagulatory proteins and platelets.

Results and discussion

We calculated the elastic shear modulus of standard MA (Gt) and HVG MA (GH), which reflect the total clot strength and procoagulatory protein component, respectively. The difference was an estimate of the platelet component (Gp). There was a 14% perioperative increase of standard MA, corresponding to a 48% increase of Gt (P < 0. 05) and an 80–86% contribution of the calculated Gp to Gt. We conclude that serial standard TEG and the HVG viscoelastic test may reveal the independent contribution of platelets and procoagulatory proteins to clot strength. Using multiple linear regression, all coagulation, TEG and HVG variabilities were used to model postoperative hypercoagulation. Results showed that some components of the TEG failed to identify hypercoagulation (r < 0.2, P > 0.75). However, three components of the routine coagulation assay, including bleeding time, prothrombin time, and platelet count, could be modeled to show prolonged postoperative hypercoagulability (P < 0.01). We conclude that all components of the HVG test reflect postoperative coagulopathies; these results suggest that it may be useful in determining the coagulation status of cancer patients perioperatively.

Conclusion

Postoperative hypercoagulability, occurring for at least 1 week after major cancer abdominal surgery, may be demonstrated by the HVG viscoelastic test. This hypercoagulability is not reflected completely by standard coagulation monitoring and TEG, and seems to be predominantly caused by increased platelet reactivity. The HVG viscoelastic test provides a fast and easy to perform bedside test to quantify in vitro hemocoagulation.