Irreversibility in the Post-Transfusion Phase of Hemorrhagic Shock

Abstract

The concept of irreversibility in shock was popularized by Wiggers (94) about two decades ago. He demonstrated that, if dogs are bled enough to create profound hypotension, early replacement of normal blood volume results in survival, while late replacement is followed by a gradual drop in blood pressure and death—despite post-treatment restoration of blood pressure to normal and a normal blood volume. Wiggers called this latter phase “normovolemic shock” and indicated that it was resistant to all modes of therapy then current. Some feel that this concept is of little use in describing clinical shock, stating (a) that human shock is rarely permitted to reach the levels used in canine experiments, (b) that no such clear-cut moment exists in clinical shock when irreversibility supervenes, and (c) that, in any case, the dog is an unacceptable model for human shock (64). However, the concept of irreversibility persists as a challenge to many investigators and appears to have outgrown the old connotations of the experimental model, reflecting instead the current state of the art. Thus, clinical shock which fails to respond to all the agents we command is irreversible.