Effects of the HEET garment in the prevention of hypothermia in a porcine model.

Background: Hypothermia is a common battlefield trauma occurrence. This study compared the effectiveness of the hypothermia, environmental, exposure, and trauma (HEET) garment (Trident Industries, Beaufort, SC) with and without thermal inserts with a control group of two wool blankets in the prevention of hypothermia in a treated hypovolemic porcine model.

Materials And Methods: Five female swine (Sus scrofa-Yorkshire cross) were assigned to each of three groups: HEET with thermal inserts (n=5); HEET without thermal inserts (n=5); or control (n=5). After the animals were anesthetized and stabilized for 30 min, the swine were hemorrhaged to a mean arterial pressure (MAP) of 30 mm Hg, simulating a battlefield injury. Hetastarch 6% (500 mL) was rapidly administered, simulating initial field resuscitation. One hour later, the animals' shed blood was reinfused, simulating transfusion at a field medical facility. The investigators moved the animal into a cooler set at 10°C ± 0.5°C. A pulmonary artery catheter was used to monitor core body temperature over a 6-h period.

Results: A repeated measures ANOVA and Tukey's post hoc test were used to analyze the data. There was a significant difference between the groups. At the end of 6h, the mean core temperature for the HEET with inserts group was 32.69°C ± 1.5; the HEET without inserts, 31.02°C ± 1.8; and control, 34.78°C ± 1.2 (P<0.05). While all groups became hypothermic, the wool blanket group was most effective in maintaining body temperature closer to normothermia.

Conclusion: The HEET garments with and without heaters are ineffective in preventing hypothermia.