Hemodynamic effects of dopamine during thoracic epidural analgesia in man

The cardiovascular effects of dopamine were studied before and during thoracic epidural analgesia (TEA) in eight patients prior to abdominal aortic surgery. Dopamine was infused at rates of 2, 4, and 8 micrograms X kg-1 X min-1. Mean plasma dopamine concentration increased proportionally to the infusion rate. Before TEA, dopamine 8 micrograms X kg-1 X min-1 decreased systemic vascular resistance 4 +/- 4 mmHg min X 1-1 (m +/- SD) (P less than 0.05), but increased mean arterial pressure 15 +/- 12 mmHg (P less than 0.01), cardiac output 1.9 +/- 1.0 1 X min-1 (P less than 0.01), heart rate 10 +/- 9 beats X min-1 (P less than 0.05), and plasma norepinephrine concentration 544 +/- 252 pg X ml-1 (P less than 0.01). After the induction of TEA, which extended above the T2 dermatome and below the L2 dermatome, saline and albumin were infused to maintain central venous and pulmonary capillary wedge pressures. TEA reduced mean arterial pressure from 96 +/- 18 to 55 +/- 8 mmHg (P less than 0.01), cardiac output from 4.7 +/- 0.9 to 3.9 +/- 0.9 1 X min-1 (P = 0.05), systemic vascular resistance from 21 +/- 6 to 14 +/- 3 mmHg min X 1-1 (P less than 0.05), and plasma norepinephrine concentration from 394 +/- 141 to 207 +/- 73 pg X ml-1 (P less than 0.01). The plasma epinephrine concentration was reduced 49% after the induction of TEA.(ABSTRACT TRUNCATED AT 250 WORDS)