Scales of Reaction to Electric Shock

It is important for the physician to understand the range of potential reactions that may result from electric shock. This presentation will give a broad overview of reactions to electric shock and the underlying biophysical mechanisms. A more detailed discussion is given in reference 1, from which some of the material presented here has been adapted. FIGURE 1 suggests several scales for characterizing physical reactions to electric shock. The figure applies to an example in which a large adult subject grips a large electrode; a return electrode is at the feet; a 60-Hz current flows for a period of 5 seconds. The five columns represent distinct continua of potential reactions; approximate median thresholds for various end points are read on the left-hand scale. The gray scale used in the figure is intended to convey the intensity of the effect along each continuum. We will use this example as a point of reference in discussing the important variables and reactions in electric shock. This paper will emphasize excitable tissue responses (the first three categories); thermal effects and electroporation (EP) are emphasized by other presenters, but will be treated here in brief. Particular end points in FIGURE 1 are only approximate for the cited conditions. Many variables influence biophysical responses to electric shock. TABLE 1 gives a rough indication of these variables and their relative importance to the response categories of FIGURE 1.