Experimental study of irreversible shock and the brain

✓ The roles of various organ systems in preventing the phenomenon of irreversible hemorrhagic shock were studied in dogs by artificially maintaining or depriving these systems of circulation. It was found that depriving the abdominal viscera of circulation did not necessarily result in death if the heart and brain were perfused. If the heart was maintained at normal pressures while the rest of the body was subjected to what would have otherwise been a lethal period of shock, the animal nevertheless survived. Thus, in the standard “35 mm Hg shock model” the heart seemed to be crucial. However, in the “30 mm Hg shock model” death occurred even if the heart was adequately perfused, indicating that failure of neural mechanisms accounts for irreversibility at these levels of hypotension.