Arterial and venous plasma levels of bupivacaine following epidural and intercostal nerve blocks.

Arterial and peripheral venous plasma levels of bupivacaine were determined in 30 patients following epidural anesthesia using 150 and 225 mg, as well as following intercostal nerve block with 400 mg. Arterial levels were consistently higher than levels in simultaneously sampled venous blood, and the highest levels occurred with bilateral intercostal nerve block. No evidence of systemic toxicity was observed. The results suggest that bupivacaine may have a wider margin of safety in man than is now stated.