TEMPERATURE CORRECTED THROMBELASTOGRAPHY IN HYPOTHERMIC PATIENTS

Thrombelastograms and other coagulation studies are performed at 37 de grees C, regardless of the patient's body temperature. This prospectiv e study of 45 patients undergoing orthotopic liver transplantation was conducted to evaluate the effect on the thrombelastogram performed at the patient's actual body temperature compared with a control thrombe lastogram heated in the standard fashion to 37 degrees C. Thrombelasto grams were obtained after the induction of anesthesia and at various t imes throughout the operation when clinically indicated. A freshly dra wn sample of the patient's blood was divided into two aliquots and run simultaneously on two thrombelastographs; one thrombelastograph was m odified with a thermostat to perform the test at the patient's body te mperature and the other was unmodified to serve as a control. The temp erature of the patients in this study ranged from 36.9 degrees C to 32 degrees C. The variables of the thrombelastogram measured were: r (re action time in minutes), r + K (coagulation time in minutes), alpha (c oagulation rate in degrees), and MA (maximum amplitude in millimeters) . Whenever the patient's body temperature was less than 37 degrees C, statistically significant prolongation of the reaction time, coagulati on time, and decrease in the clot formation rate occurred compared wit h control variables at 37 degrees C. Overall means were as follows: r for control, 8.24 +/- 0.28 min; r for temperature corrected, 9.32 +/- 0.27 min; r + K for control, 15.4 +/- 0.65 min; r + K for temperature corrected, 17.5 +/- 0.81 min; and alpha for control, 39.8 +/- 1.22 deg rees; alpha for temperature corrected, 37.7 +/- 1.23 degrees. The MA w as not significantly different between the temperature corrected throm belastograms and the control thrombelastograms regardless of the patie nt's body temperature. These changes suggest that performing thrombela stograms in the standard fashion may overestimate the quality of the c oagulation system in vivo when the patient's temperature is less than 37 degrees C.