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

Cardiac performance was evaluated during haemorrhagic 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 mmHg 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. In addition, 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 haemorrhage. The greater reduction in left ventricular performance during haemorrhagic 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 haemorrhagic shock. This study suggests that, in dogs, the spleen maintains left ventricular performance during haemorrhage by mechanisms other than autotransfusion.