Acute systemic toxicity from bupivacaine during epidural anesthesia in obstetric patients.

Convulsions occurred within 30 seconds after the injection of bupivacaine through the epidural catheter in four obstetric patients in labor, and mild excitation without convulsions occurred in three others. Since the time between injection and the reaction was so short and since the dose was so small, the response probably was due to intravenous injection resulting from lodgement of the catheter in a vein, rather than to absorption from the epidural space itself. It is not generally known that the epidural veins become thin-walled and engorged during labor; thus, inadvertent placement of a cathether in a vein can occur readily. Convulsions, therefore, may follow even injection of a test dose of a drug. Other colleagues have had similar though unreported experiences. Physicians performing epidural blocks should be aware that such an occurrence is possible and that the catheter may be within a vein without blood returning on aspiration.