Volume expansion, dobutamine and noradrenaline for treatment of right ventricular dysfunction in porcine septic shock: a combined invasive and radionuclide study.

The purposes of the present study were 1) to explore if volume loading in combination with dobutamine or noradrenaline would be superior to volume loading alone in the treatment of right ventricular (RV) dysfunction in septic shock complicated by acute pulmonary hypertension and 2) to determine whether noradrenaline would be superior to dobutamine because of its vasoconstrictor effects on the peripheral circulation, resulting in increased RV coronary perfusion pressure. Experiments were performed on 21 anesthetized, ventilated pigs. Gated blood pool studies and hemodynamic measurements were performed simultaneously. All animals were given 3-4 X 10(8)/kg live E. coli bacteria, resulting in an abrupt increase in pulmonary arterial pressure and a decrease in arterial pressure, cardiac output, and RV ejection fraction. Right ventricular end-systolic volume was unchanged; RV end-diastolic volume and RV coronary perfusion pressure fell. After randomization, the control group (I, n = 5) was subjected to volume loading, and treatment groups (each n = 8) received volume loading in combination with dobutamine (group II, 5-10 micrograms/kg/min) or noradrenaline (group III, 0.25-0.50 micrograms/kg/min). In contrast to volume loading alone, dobutamine and noradrenaline increased cardiac output and RV ejection fraction, but only noradrenaline restored mean arterial pressure. Noradrenaline improved RV contractility, as judged from the RV end-systolic pressure-volume relationship, probably because it increased the RV perfusion. Thus, noradrenaline in combination with volume loading may be the treatment of choice to improve RV performance in porcine septic shock associated with pulmonary hypertension.