Metaraminol and dobutamine for the treatment of hypotension associated with epidural block.

In 14 patients undergoing major abdominal surgery, epidural analgesia was performed and cardiovascular changes were examined by insertion of Swan-Ganz catheters. To counteract the hypotensive episodes associated with epidural block, Dobutamine (1-3 micrograms/kg body wt min-1) and Metaraminol (0.5-1.5 micrograms/kg body wt min-1) in various doses were infused and the effects of these vasoactive agents were examined. Epidural analgesia decreased arterial pressure, pulmonary arterial pressure, pulmonary capillary wedge pressure and central venous pressure associated with marked decrease in cardiac index, stroke volume index, left ventricular and right ventricular stroke work without changes in systematic vascular resistance, pulmonary vascular resistance or heart rate. The infusion of Metaraminol caused a marked increase in arterial pressure, pulmonary arterial pressure, wedge pressure and central venous pressure. Calculated variables of stroke volume, systemic vascular resistance, left and right stroke work and cardiac work increased significantly. The infusion of Dobutamine caused a marked increase in arterial and pulmonary arterial pressure, wedge pressure, central venous pressure and cardiac index associated with those calculated changes of left and right stroke work and cardiac work, which were increased markedly. On the other hand, heart rate, stroke volume and pulmonary vascular resistance did not show any remarkable changes. Our study indicates that the fall in arterial blood pressure associated with epidural block may be due to marked decrease in cardiac output, and the infusion of Dobutamine is one of the desirable methods to counteract the hypotensive episode.