Effect of dobutamine on oxygen consumption and fluid and protein losses after endotoxemia

OBJECTIVETo determine the effect of a dobutamine infusion on the relationship between oxygen consumption ( o2) and oxygen delivery (Ḋo2) after endotoxin administration, as well as the rate of fluid and protein loss from permeability-injured tissue. METHODSUnanesthetized adult sheep with lung and soft-tissue lymph fistulas were given 5 μg/kg Escherichia coli endotoxin alone, or E. coli endotoxin plus a continuous infusion of dobutamine (10 to 15 μg/kg.min) beginning at 3 hrs. Lymph flow reflected the vascular permeability and surface area perfused. Data were compared with dobutamine alone and with controls. Filling pressures were maintained at baseline. RESULTSDobutamine alone produced a 75% increase in Ḋo2, a transient 10 ± 4% increase in o2, but no increase in lung or soft-tissue lymph flow. Beginning at 3 hrs after endotoxin alone, a significant increase in protein-rich lung and soft-tissue lymph flow was noted, but only a transient 14 ± 5% increase in o2. Plasma proteins were slightly decreased. With the addition of dobutamine at 3 hrs postendotoxin, Ḋo2 increased by >50% for the 3-hr infusion period, while Ḋo2 increased for a 30-min period by 25 ± 8%, which was not different than endotoxin alone. Lung and soft-tissue lymph flow did not increase further, but plasma proteins did decrease significantly compared with controls and with endotoxin alone. CONCLUSIONIncreasing Ḋo2 with dobutamine postendotoxin does not increase the surface area perfused or the edema process, at least in lung and soft tissue. Therefore, no microvessels in these tissues are reopened with dobutamine when normal filling pressures are present. Dobutamine administration does not increase o2 more than the increase seen with endotoxin alone. (Crit Care Med 1991; 19:525)