The course of events in secondary wound shock / W.B. Cannon.

  • Walter Bradford Cannon
Date:
1919
Catalogue details

Licence: Public Domain Mark

Credit: The course of events in secondary wound shock / W.B. Cannon. Source: Wellcome Collection.

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    Us lactate, thus diminishing the alkali reserve. The car- bon dioxid which is set free will, of course, be promptly eliminated. DANGER FROM INSUFFICIENT OXYGEN SUPPLY On the basis of the foregoing evidence, the acidosis which appears as the blood pressure is lowered, though not dangerous in itself, is an indication of a really serious danger, namely, the danger arising from insuf- ficient oxygen supply. The tissues of the body are known to vary greatly in their sensitiveness to oxygen want. Some muscles will endure total anemia for at least three hours with- out undergoing destructive alterations. On the other hand, certain nerve cells of the cerebral cortex cannot endure total anemia for more than seven or eight min- utes without suffering changes so profound as to be irreversible. There is especial danger, consequently, | that the nervous system will be damaged by persistence of the blood pressure below the critical level. As shown in Figure 4, the blood pressure may be lowered to 60 mm. of mercury for an hour, and at the end of that time, if the pressure is allowed to rise, it will be nearly restored to its normal level. If now the pressure is again lowered to 60 mm. and held there for an hour, it does not rise so high; and when held to this low level for another hour, it may not rise at all. Examination of the blood under these circumstances indicates that there has been no material escape of fluid from the vessels. The failure of the pressure to rise after persistence at the low level is to be regarded, therefore, as dependent on the damage done to control of the circulation by the inadequacy of the circulation itself. 3 The facts just developed offer a basis for the sim- ilarity which has been repeatedly noted between the phenomena of shock and the phenomena of hemor- rhage. After the blood pressure has once been lowered in shock, the effects on the organism are in all respects similar to those which are produced by a marked loss of blood. The dictum of the older surgeons that “shock is hemorrhage and hemorrhage is shock” is - thus justified. The significance of this similarity in the treatment of both shock and hemorrhage will appear later.
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