Abstract
In a recent communication we have shown that the essential factor of shock is a disturbance in the normal distribution of the blood. This disturbance is of such a character that the normal quota upon the arterial side of the circulation is diminished and this diminution is maintained so that, as a consequence, even after the original cause of the disturbed distribution of the blood, whether of a mechanical, toxic or inhibitory nature, is removed the abnormal diminution of the blood upon the arterial side of the circulation not only persists but, in fatal cases, progresses from local peripheral causes alone until death occurs.
The reality and nature of these local factors in the production of shock is made clearest in that form of shock which is produced by mechanical means alone, because in shock created in this manner no other factor can enter except the consequences of a primary disturbance of the normal distribution of the blood.
The mechanical means which we adopted for the production of shock was that used for the reduction of blood pressure when testing out the shock-producing effect of trauma to the peripheral sensory nerves. It consisted in partially occluding the inferior vena cava within the chest by passing a thread around the vein and drawing out the two ends through the incision in the wall of the thorax. By the degree of tension exerted on this thread, the amount of blood passing from the veins to the arterial side of the circulation could be accurately controlled and, in consequence, the blood pressure.
It was found that a two-hour period of reduction of the arterial blood pressure to from 30 to 40 mm. of Hg was, with few exceptions, fatal within the next eighteen hours, even though there might be a rise of arterial blood pressure to nearly the normal height for a period of three to four hours after the release of the ligature around the inferior vena cava.
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