A method of producing experimental shock

Abstract

In the numerous investigations on experimental shock there is no uniformity as to the method of inducing it. Some authors simply say “the animal was reduced to shock,” without stating by what method it was induced or how long it took to induce it. Others claim that they have produced profound shock by continuous stimulation of sensory nerves, while other writers are quite positive that it is impossible to induce shock by this method. The method par excellence of producing shock seems to be the exposure of the abdominal viscera. Here again opinions differ. For instance, Erlanger and his coworkers say that in order to reduce blood pressure to 50 mm. mercury, an exposure and manipulation of the intestines lasting from two to five hours is necessary. In the studies of shock by Githens and Meltzer “the intestines and stomach were dislocated and frequently handled.” Wiggers on the other hand states that a more regular and certain circulatory failure is induced when the intestinal loops are not manipulated. Many investigators kept the animals under surgical anesthesia throughout the experiment or at least during the greatest part of it.

Generally the fall of blood pressure is the sole criterion of shock. In the studies of Githens and Meltzer the fall of blood pressure and also the disappearance of pain sense were taken as criteria. They studied these phenomena an hour or more after the discontinuation of ether. Of forty-two dogs, in fifteen the blood pressure did not reach a level below 95 mm. within five hours after opening the abdomen, and pain sense returned as soon as the animals came out of ether. In only thirteen dogs the blood pressure reached a level below 70 mm. within two and a half hours and there was no return of pain sense.