STUDIES ON FROST-BITE WITH SPECIAL REFERENCE TO TREATMENT AND THE EFFECT ON MINUTE BLOOD VESSELS

Abstract

The lack of adequate information as to the nature of the lesion caused by freezing has made difficult the development of a rational therapeutic procedure. Development of a reliable method of freezing was undertaken and one adopted which consisted of immersing the anterior extremities of rabbits in absolute alc. to which pieces of CO2 ice were added until the desired temp. was obtained. The extremity was frozen at various temps. for different lengths of time. Immersion of the foot in the freezing mixture for 3 mins. at a temp. of [long dash] 40[degree]C usually resulted in total destruction of the frost-bitten part. A similar result followed freezing the extremity at [long dash]20[degree]C for 20 mins. Many of the methods of treatment employed by previous workers as well as those used by the medical corps of the-army were studied. Briefly, the results were discouraging. Without a knowledge of the severity of the injury resulting from frost-bite, an evaluation of the effectiveness of a given treatment cannot be made. It has long been thought that frost-bite results in coagulation of the blood in the smaller vessels and eventual anoxia which causes further destruction of the frost-bitten tissue. The Florey modification of the Clark transparent chamber was inserted into the ears of rabbits. Pieces of CO2 ice were applied directly to the window for 30 sees. The vessels that had grown into the chamber were completely frozen. Immediately after thawing, the vessels appeared normal in every respect. However, 5 or 10 mins. later it was apparent that serious injury had been done. The vessels dilated widely and became filled with red and white blood cells. The permeability of the walls of the vessels increased, the plasma was drained from the vessels and the formed elements were left concentrated in the vessels in conglomerate masses. These masses were not due to coagulation since an identical picture was seen in the vessels of animals whose blood had been made noncoagulable by injn. of heparin.