The influence of body temperature on traumatic vasospasm.

The effect of hypothermia on traumatically induced vasospasm was studied in an in vivo model of the rabbit ear artery. Spasm was induced by standardized compression of a 3.2 mm segment of the artery for 3 s. The internal diameter was continuously measured with the aid of an operating microscope during transillumination of the artery. Measurements were begun before spasm induction and continued until the spasm was completely resolved. Spasm was first induced at normothermia and then after reduction of the body temperature by 1.0 degrees C and 1.75 degrees C. The spasm was evaluated in terms of its duration, intensity (% reduction of initial diameter) and severity (area under the curve where diameter was plotted against time). The results were compared with those in a control group which was kept normothermic. Reduction of the body temperature caused a significant increase in the duration of the spasm and increased its severity, but did not influence its intensity.