The effects of intentional hyperthermia on the Thrombelastograph and the Sonoclot analyser

The effect of whole-body hyperthermia (WBH) on viscoelastic properties of whole blood, as measured by the thrombelastogram (TEG) and Sonoclot analyser, was investigated in 10 patients undergoing WBH-carboplastin therapy for metastatic disease. Blood was taken from an existing central line at baseline (37°C), during warming (39 and 41°C) and cooling (39 and 37°C). Sonoclot and TEG samples were analysed simultaneously at 37°C and at the patient's temperature with a temperature-compensated unit, except at 41°C for the Sonoclot (maximum temperature adjustment of 40°C). TEG measurements included R time (time to initial fibrin formation [mm]), K time (mm) and alpha angle (degrees) (both reflecting fibrinogen-platelet interaction), maximum amplitude (representing qualitative platelet function [mm]) and per cent fibrinolysis at 30 and 60 min. The Sonoclot ACT (SonACT-secs), initial rate of clot formation (%), time to peak amplitude (min) and peak amplitude of the Sonoclot signature (mm) were recorded. Decreased R time of the TEG compared to a marginally elevated baseline was found at all times during warming and cooling (p < 0.05). The K time was decreased at 41°C compared to a normal baseline (p < 0.05). The SonACT was decreased (from an elevated baseline) at all other times, without differences in measures at patient temperature versus 37°C (p < 0.05). The data suggest acceleration of fibrin formation during WBH to 41°C in patients with malignancy. Implications for defining thromboembolic risk require further investigation.