This study was undertaken in an attempt to establish a method of bleeding rats and autotransfusing the blood removed from them which would be associated with a mortality of near 50%. The use of different combinations of fluids as therapy for hemorrhage in the rat could be assessed optimally, since the likelihood of a given method of treatment being both better or worse than autotransfusing all the blood removed can best be determined when the latter is associated with a mortality of 50%.
A previous study from this laboratory reported a hemorrhagic shock model in the rat which was based upon bleeding to a mean blood pressure of 30 mm Hg for 60 minutes.1 This model was associated with a mortality of only 24% among rats surviving to be treated by returning all the blood removed from them. When the duration of hypotension was lengthened more rats died before
Collins JA, Braitberg A, Margraf HW, Butcher HR. Hemorrhagic Shock in RatsMeasured Blood Volumes as the Basis for the Extent of Hemorrhage. Arch Surg. 1969;99(4):484–488. doi:10.1001/archsurg.1969.01340160064015