Abstract
It can be shown that the stationary temperature which results after sending an electric current through tissue for a considerable time depends mainly on 4 factors: (1) the current intensity, (2) the cross section of the tissue penetrated by the current, (3) the specific resistance of the tissue, (4) and the heat conductivity of the tissue, which depends primarily upon the blood circulation. The importance of this factor has been demonstrated conclusively by a recent investigation about the effect of electric currents upon the blood vessels. 1
The specific resistance is of prime importance, because, in addition to determining the heating effect of a given current, it also influences the path of the current, as soon as this resistance varies over the volume of tissue in question. Therefore the experimental determination of the resistance of the various tissues of the human body as of the animal is of great importance.
Omitting the meagre literature 2 , 3 about the subject I will describe shortly the experiments which I have conducted partly in collaboration with W. S. Brown:
(1) Eight different organs of a dog were exposed to 3 kinds of current: a. Direct current; b. an alternating current; c. a high frequency current.
(2) These experiments were made under 3 different conditions: (a) in vivo, the dog being anesthetized; (b) the organs being left in position, right after the dog had been killed; (c) the organs removed, kept on ice for one night and then brought back nearly to room temperature.
(3) The same organs were taken from fresh bodies and exposed to the same 3 kinds of currents.
By these experiments could be determined: (1) the individual resistance of each organ; (2) the effects which are due to the special character of the current; (3) the influence of the condition of the material (live, dead, fresh, old, etc.); special care was taken in case of the lungs (inflated, collapsed).
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