Dopexamine hydrochloride in septic shock: Effects on oxygen delivery and oxygenation of gut, liver, and muscle

It has been suggested that septic shock is a disorder of microvascular autoregulation. Tissue blood flow is modulated by the state of activation of upstream endothelial receptors controlling the vascular smooth muscle tone. Because vascular receptor populations vary between organs, it should be expected that vasoactive drugs affect tissue oxygenation differently in different organs. We studied the effects of dopexamine HCl (a novel inotrope) and septic shock on oxygen delivery as well as tissue P(O₂) in gut, liver, and skeletal muscle in anesthetized rabbits. Employing the thermodilution technique, cardiac output was measured across the pulmonary bed and used to calculate oxygen delivery. Three eight-channel Mehrdraht Dortmund Oberflache oxygen electrodes were placed on gut serosa, liver, and skeletal muscle surfaces, respectively, and sufficient readings were obtained to calculate tissue P(O₂) distributions. During septic shock mean arterial pressure, cardiac output, oxygen delivery, and mean tissue P(O₂) decreased in all organs, Our results suggest that the observed changes in tissue oxygenation during septic shock were caused by defective regulation of microvascular blood flow. In conclusion, during baseline conditions dopexamine HCl caused no statistically significant changes in tissue oxygenation in any organ, except in skeletal muscle at 10 μg/kg/min when tissue P(O₂) increased. During septic shock, however, dopexamine HCl improved oxygenation in all three organs in a dose-dependent manner.