EFFECTS OF DOBUTAMINE ON HEPATO-SPLANCHNIC HEMODYNAMICS IN AN EXPERIMENTAL MODEL OF HYPERDYNAMIC ENDOTOXIC SHOCK

Dobutamine infusion has been proposed to increase splanchnic blood flow in septic conditions, but its' effects on liver blood flow and metabolism have not been well defined. We investigated the effects of dobutamine on liver blood flow, metabolism, and pathology in a canine hyperdynamic endotoxic shock model. Twenty-one dogs were anesthetized and paralyzed. After the administration of 2 mg/kg endotoxin, normal saline was infused to restore the pulmonary artery-occluded pressure to 10 mmHg. The dogs were then randomized to receive fluids either alone (n = 7) or combined with a dobutamine infusion at a rate of 5 (n = 7) or 10 microg/kg per min (n = 7). After initial fluid resuscitation, cardiac index (CI) increased from 152+/-48 to 386+/-97 mL/kg per min (P < 0.01) and then slightly decreased with time in the control group, but further increased to 458+/-54 mL/kg per min (P< 0.05) and remained elevated in the group treated with 5 microg/kg per min of dobutamine. Portal vein and hepatic arterial blood flows followed a similar course and increased with fluid resuscitation. Both decreased with time in the control group, but further increased in the dobutamine-treated animals. Liver oxygen delivery (DO2liv) increased with fluids from 2.2+/-2.4 to 3.8+/-1.9 mL/kg per min (P < 0.01) and further increased in the dobutamine-treated animals to 4.1+/-1.2 mL/kg per min. This was associated with an increase in liver oxygen uptake from 1.6+/-1.6 to 2.9+/-1.1 mL/kg per min with fluid resuscitation and a further increase to 4.3+/-1.5 mL/kg per min with dobutamine administration. Lactate consumption and hepatic vein oxygen saturation increased with initial fluid resuscitation and then decreased with time in the control group, but not in the dobutamine-treated animals. Increasing the dose of dobutamine to 10 microg/kg per min did not alter this response. At the end of the experiment, liver tissue samples were obtained for microscopic studies. The histological lesions seen in the control group were unaffected by dobutamine. In conclusion, dobutamine increases liver blood flow and metabolism, but does not affect microscopic findings in this hyperdynamic endotoxic shock model.