Plasma bupivacaine levels after pleural block: the effect of epinephrine after unilateral or bilateral bupivacaine administration.

Abstract

To determine the effect of adding epinephrine (5 micrograms/ml) to bupivacaine during continuous spinal infusion and the effect of the administration of the same total dose of bupivacaine, in a bilateral or unilateral way, on its consequent plasma levels. Sixteen cholecystectomized patients were studied prospectively. In ten patients with midline incision, bilateral pleural infusion (half total unilateral dose in each hemithorax) was administered, and in six patients with subcostal incision, unilateral pleural infusion. The unilateral group received a loading dose of 20 ml 0.375% bupivacaine immediately followed by an infusion at a rate of 6 ml/hour. Three patients randomly received epinephrine (5 micrograms/ml) added to bupivacaine, whereas the other three remaining patients did not receive it. The bilateral group received 10 ml 0.375% bupivacaine followed by an infusion at a rate of 3 ml/hour in each hemithorax. Five patients randomly received epinephrine; five others did not. The plasma levels of bupivacaine were determined at 5, 15, 30, and 60 minutes and at 6 and 18 hours. Plasma levels of bupivacaine were significantly lower (p less than 0.05) during the whole study in patients receiving epinephrine. For the same total dose, there were no statistical differences in the plasma levels of bupivacaine between unilateral and bilateral pleural groups. The addition of epinephrine (5 micrograms/ml) to a continuous pleural infusion of bupivacaine diminishes the plasma levels of the local anesthetic. For the same total dose of bupivacaine, there are no differences in the plasma levels obtained between unilateral and bilateral administration.