Methods for measuring the resistance at any point on the body and for equalizing inequalities of skin resistance.

When standard leads or ordinary prncordial leads are taken with a string galvanometer electro-cardiograph, the resistance of the patient can be measured for each lead. However, no method has been described previously by which the resistance at any of the extremities or at any point on the body can be measured. A method for doing this is described below. Principle. When the standard leads are taken, the resistance of the patient as measured consists of the resistance of the skin at the points of electrode contact and the resistance of the body tissues and fluids. Thus, the resistance of the patient measured from lead I includes the resistance of the point of right-arm electrode contact, the resistance of the point of left-arm electrode contact, and the resistance of the body tissues and fluids. Similar situations hold for the resistances of the patient when lead II, III, or any bipolar lead is taken. However, for the purposes of this paper, we shall assume that practically all the resistance of the patient is centred at the two points of extremity-electrode contact for each lead. Studies have been made which indicate that the resistance of the body tissues and fluids is at most only a few hundred ohms (Richter and Woodruff, 1941). Even if the resistance of the body fluids and tissues were of magnitude, this would only change the' results quantitatively but not qualitatively because the resistances of the body fluids and tissues are equal (Kaufman and Johnston, 1943).