Total body blood volume redistribution in porcine E. coli septic shock: effect of volume loading, dobutamine, and norepinephrine.

The purpose of the present study was to determine the effect of volume loading alone (CONTR) vs. volume loading in combination with dobutamine (DOBU) or norepinephrine (NOR) on total body blood volume distribution in septic shock. After instrumentation, injection of in vitro labelled 99mTc red blood cells, and baseline measurements, anesthetized, ventilated pigs (n = 21) received 3-4.10(8).kg-1 live E. coli bacteria intravenously. Images of thorax, abdomen, and hindlimb were obtained by using a gamma camera simultaneously with hemodynamic measurements. E. coli infusion resulted in a decrease in arterial pressure, ventricular filling pressures, and cardiac output with a concomitant increase in pulmonary arterial pressure. Blood volume was redistributed from the heart, lungs, spleen, abdomen, and leg to the liver. After randomization, the CONTR group (I, n = 5) was subjected to volume loading, and treatment groups (each n = 8) received volume loading in combination with DOBU (group II, 5-10 micrograms/kg/min) or NOR (group III, 0.25-0.50 micrograms/kg/min). As compared to volume loading alone, DOBU and NOR increased cardiac output but only NOR restored arterial pressure. Volume loading increased blood volume in all regions studied; however, it was unequally distributed amongst organs with a preference for the liver. Neither DOBU nor NOR influenced the partitioning of the infused volume between organs. However, NOR prevented pooling of blood in the leg.