VASODILATATION IN THE LOWER EXTREMITIES IN RESPONSE TO IMMERSING THE FOREARMS IN WARM WATER

Abstract

Several tests have been proposed, and are now in general use, for estimating the grade of organic occlusion existing in the blood vessels of an extremity. The principle underlying these various methods is similar. The surface temperature of the distal portion of the cool, exposed extremity is measured thermo-electrically. Dilatation of the peripheral vessels is then produced and the coincident rise in surface temperature is recorded. The level to which the temperature rises with complete vaso-dilatation has been determined in individuals with normal peripheral circulation. If the surface temperature fails to rise to this normal level, the arteries supplying the part are regarded as being unable to dilate due to organic changes in their walls. One of the earliest methods of producing vasodilatation in the extremities in man was suggested by Brown (1) and consists in producing fever by the intravenous injection of typhoid vaccine. Morton and Scott (2) induced vasodilatation in the lower limbs by means of spinal anesthesia, and later proposed the use of general anesthesia, ether, nitrous oxide or ethylene (3), for the same purpose. Injection of peripheral nerves with novocaine has also been used to produce local vasodilatation by White (4), Lewis (5), and Scott and Morton (6). Still more recently Lewis and Pickering (7) studied the vasodilatation in the hands produced by warming the body. The subject was seated in a small hot air chamber with the head and hands projecting into a cool room. Heating the air in the chamber to a temperature of 460 C. or more was followed by a rise in the skin temperature of the hands. They suggest that the method may also be used to produce vasodilatation in the feet. The following report describes the effects which warming one or two extremities exerts on the skin temperature of the other extremities, with special emphasis on the vasodilatation in the feet produced by immersing the forearms in warm water. The mechanism by which this vasodilata-tion is induced has been studied in normal subjects. The simplicity of the method and apparatus, as well as the constancy of the reaction in normal subjects, suggests that the procedure may have a certain value in the 1019