COAGULATION DEFECTS RESULTING FROM AMBIENT TEMPERATURE-INDUCED HYPOTHERMIA

Ambient temperature-induced hypothermia noted in trauma patients is fr equently accompanied by a bleeding diathesis despite ''laboratory norm al'' coagulation values. To document this impression, the following ex periment was conducted. Coagulation studies and platelet function stud ies were performed in ten minipigs during induced whole body hypotherm ia (40-degrees-C to 34-degrees-C) and rewarming. Cooling was achieved in 2 to 3 hours and rewarming took 4 to 5 hours. In addition, similar coagulation and platelet function studies were conducted on plasma sam ples from the same animals that were cooled and then rewarmed in a wat er bath. Platelet counts and function as measured by Sonoclot analysis and aggregation did not decrease significantly with hypothermia in ei ther model. Plasma cooled in a water bath demonstrated abnormal PT and aPTT (p < 0.001). Whole body hypothermia demonstrated abnormal bleedi ng time and PT (p < 0.001). Ambient temperature-induced hypothermia pr oduced significant coagulation defects in a porcine model. Some of the coagulation defects were most pronounced during rewarming.