Cardiovascular effects of haemorrhagic shock in spleen intact and in splenectomized dogs

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Abstract
Cardiac performance was evaluated during hemorrhagic shock in 27 dogs with spleens intact, 24 splenectomized and 23 splenectomized transfused dogs that were given a volume of packed red blood cells simulating splenic contraction. Contractile changes were evaluated by calculating dP/dt at 20 mm Hg developed pressure (dP/dt DP20), and by relating stroke work to left ventricular end-diastolic volume measured by biplane cinefluorography. Although heart rate increased comparably during early shock, cardiac output, stroke volume, maximal dP/dt, dP/dt DP20 and arterial blood pressure decreased more in splenectomized and splenectomized transfused dogs than in those with spleens intact. During shock dP/dt DP20 was more depressed in the splenectomized and splenectomized transfused dogs than in those with spleens intact. An increase in left ventricular end-diastolic volume was accompanied by an increase in left ventricular stroke work in dogs with spleens intact. In contrast, stroke work remained depressed in both splenectomized groups despite increased left ventricular volume. Progressive acidosis and decreased left ventricular blood flow were similar in all dogs during hemorrhage. The greater reduction in left ventricular performance during hemorrhagic shock in the splenectomized and splenectomized transfused dogs was not related to excess lactate, changes in plasma volume, or red blood cell mass. Decreased left ventricular performance, despite improved ventricular filling, indicates greater cardiac dysfunction during hemorrhagic shock. In dogs, the spleen maintains left ventricular performance during hemorrhage by mechanisms other than autotransfusion.