[Plasma levels following lumbar epidural anesthesia with 0.75% bupivacaine]

In ten patients undergoing total hip replacement, plasma levels of bupivacaine were studied, following lumbar epidural administration, with special reference to the early phase. In contrast to previous studies concerning the 0.5% solution, we found an early rise between 3 and 5 min, which was nearly identical with the peak level. The maximum concentration was 2.76 micrograms/ml and within the estimated safety margin. The necessity of preventing acidosis and hypoxia is pointed out when using bupivacaine 0.75%.