In Vivo Coagulation—a Probable Cause of Irreversible Shock

Abstract

Previous work in the field of acute circulatory failure suggested that any period of inadequate circulation would result in the formation of a large number of small blood clots as the result of hyperactivity of the in vivo coagulability control system. Experimental hemorrhagic shock is such a period of inadequate circulation and it was noted that the blood is very hypercoagulable during hypotension. During the intense vasoconstriction, blood flow is reduced and this sluggish flow combined with the presence of an active coagulant results in the formation of thrombi. Following the reinjection of the withdrawn blood, many of these thrombi are washed out and progressively block the portal and pulmonary circulation, resulting in eventual death of the animal. In control animals (dogs), the blood was withdrawn into sodium citrate solution and 1 of 21 dogs survived. Another group of animals was given 5 mg/kg heparin 10 minutes before the initial bleeding and 6 of 12 survived. When 10 mg/kg heparin was given prophylactically, 18 of 19 animals survived.