Abstract
The experiments reported in this communication have been performed for the purpose of investigating the influence of nocuous stimuli in the production of shock, by comparing with controls the shock-producing effect of severe and prolonged electrical stimulation to the peripheral sensory nerves in animals rendered susceptible to shock-producing influences by a reduction of their blood pressure.
Although an animal may be in severe shock with a high blood pressure, yet a fall of blood pressure always occurs before death and may be regarded as the most striking characteristic of shock. A diminution of blood pressure may, therefore, be legitimately considered to favor the development of shock, in other words, to render an animal a more sensitive test-subject upon which to investigate shock-producing influences. Such a method of experimentation would avoid the difficulty in estimating different degrees of shock in the experimental animals and would permit the number of deaths of the animals of one series as compared to the results of the experiments of another series in which the animals were rendered slightly less sensitive to shock though subjected to precisely the same severity of stimulation, to determine the increased shock-producing effect of the electrical stimulation of their sensory nerves.
By passing a loop of thread around the inferior vena cava through a small incision in the chest wall, and sewing up the incision in such a manner that the loop of thread emerged in a straight line through the incision, a means was provided of so limiting the amount of blood returned to the heart that the arterial blood pressure could be reduced to any desired degree and for any length of time. At the conclusion of the experiment, one strand of the loop of thread was divided and the loop removed without additional operative procedure, or the danger of pneumothorax, and without any anatomical abnormality remaining.
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