Venous Pressure in the Rabbit Foot Before and After Freezing Injury

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Abstract
Venous pressure measurements have been made in small veins in rabbits'' hind feet before and after local freezing injury. Before freezing, venous pressures are usually between 10 and 20 cm H2O. Increases above this base-line may be seen, which rise as high as 30-40 cm H2O. These changes may occur either "spontaneously," presumably in relation to body temperature variations, or in response to "painful" stimuli. In both instances the increases in venous pressure are accompanied by increases in surface skin temperature in the feet. Venous pressure response to intrajugular injections of epinephrine are variable and may show: a decrease with carotid pressure increase; no change; or an increase after the peak carotid pressure has passed. After the foot has been frozen and thawed, venous pressures rise to levels exceeding the colloid osmotic pressure of the blood, sometimes as high as 80 cm H2O; and the response to intrajugular epinephrine injection is an increase which follows directly the increase in carotid blood pressure, indicating a loss in vasoconstrictor activity of the vessels in the injured area. These findings are consistent with the development of the gross edema which develops after freezing injury.