Therapeutic effect of mild hypothermia on severe traumatic head injury

Objective: To investigate the therapeutic effect of mild hypothermia on severe traumatic brain injury.Methods: Eighty-six in-patients with severe traumatic brain injury treated ordinarily were consecutively randomized into two groups: a hypothermia group (n=43) and a normothermia group (the control group, n=43). In the hypothermia group, the core temperature ( i.e., nasopharyngeal or brain temperature) of the patient was reduced to and maintained at 33-35℃ with a systemic cooling blanket. Natural rewarming began after 3-5 days (mean: 4.3 days) of hypothermia treatment. In the control group, the patient received no hypothermia treatment. The vital sign, extradural pressure and serum superoxide dismutase were observed and measured during treatment, and the complications as well as the Glasgow outcome scale were evaluated at 2 years after injury.Results: The mean extradural pressure in the hypothermia group ( 27.38 mm Hg± 4.88 mm Hg at 24 hours, 29.40 mm Hg± 4.50 mm Hg at 48 hours and 26.40 mm Hg± 4.13 mm Hg at 72 hours after injury) was much lower than that in the control group ( 32.63 mm Hg± 3.00 mm Hg, 34.80 mm Hg± 6.00 mm Hg and 31.81 mm Hg± 4.50 mm Hg respectively at 24, 48 and 72 hours, P< 0.05). The mean serum superoxide dismutase levels in the hypothermia group on days 3 and 7 ( 583.7 μg/L± 99.6 μg/L and 699.4 μg/L± 217.3 μg/L, respectively) were much higher than those in the control group at the same time period ( 446.6 μg/L± 79.5 μg/L and 497.1 μg/L± 101.2 μg/L, respectively, P< 0.01). The recovery rates at 2 years after injury were 65.1% in the hypothermia group and 37.2% in the control group (P< 0.05). The mortality rates were 25.6% in the hypothermia group and 51.2% in the control group (P< 0.05). The complications, including pulmonary infections, thrombocytopenia (platelet count <100× 109/L), hemorrhage in the digestive tract, electrolyte disorders and renal malfunction, were managed without severe sequelae .Conclusions: Mild hypothermia is a safe and effective therapeutic method, which can lower the extradural pressure, increase the serum superoxide dismutase and improve the neurological outcomes without severe complications in the patients with severe traumatic brain injury.