Hemodynamics and blood flow distribution in experimental shock. The effect of noradrenaline and isoproterenol.

Cardiac output, regional blood flow and other hemodynamic variables were observed on dogs in hemorrhagic and in endotoxin shock. In hemorrhagic shock, a redistribution of cardiac output from other vascular beds to the coronary circulation was seen. This was induced by vasoconstriction in all vascular regions except the coronary arteries. In endotoxin shock, vascular resistance increased in some regions and decreased in others. A redistribution in favor of the mesenteric and femoral regions was seen. The coronary circulation was relatively well maintained in either shock models. Increased oxygen extraction was seen in all vascular beds. Blood pH was decreased corresponding to the degree and duration of the shock. Only small regional variations were observed in these variables. Noradrenaline increases vascular resistance in all regions except the coronary arteries. Isoproterenol reduces vascular resistance in all areas. Both drugs have cardiotropic effects. The same response was seen in normal as well as in shocked dogs. In addition to principal shock treatment, there may still be a place for the judicious use of these drugs in shock therapy.