Accidental intravenous injection of bupivacaine: a complication of obstetrical epidural anaesthesia. Case report.

SUMMARY A primigravid patient in labour had an epileptiform convulsion following the first "top- up" injection of bupivacaine 50 mg into the epidural space. The fit was treated success- fully by artificial ventilation with oxygen and there were no subsequent ill effects in the mother. The foetus was born several hours later in good condition. The maternal venous plasma bupivacaine concentration was found to have been 2.3 yug/ml during the acute episode. An electroenceph alogram performed on the patient after discharge from hospital was reported as normal. A 25-year-old primigravida was admitted in early labour after a normal pregnancy. She had no previous medical history apart from a Fenton's operation for dyspareunia. Progress in labour was slow and difficult to assess because of vaginismus. Diamorphine 10 mg given intra- muscularly did not provide satisfactory pain relief and a lumbar epidural block was requested. With the patient in the left lateral position, the epidural space at interspace L3-4 was located using a saline-filled syringe attached to a Lee's modified Tuohy needle. A Portex Skinner epidural catheter, on insertion, entered an epidural vein and was removed. When the procedure was repeated at L2-3 no blood entered the catheter and it was advanced 2 cm into the epidural space. A test dose of bupivacaine hydrochloride 10 mg was given and 5 minutes later, bupivacaine 50 mg in a 0.5% solution without adrenaline, was injected. Satisfactory analgesia was achieved with loss of knee, ankle and anal reflexes. Vaginal examination was easy to perform and a scalp e.c.g. electrode was attached to the foetus. Ninety-five minutes later the patient became distressed and a "top-up" dose was given. No blood could be aspirated from the catheter. Following a test dose, bupi- vacaine hydrochloride 40 mg was injected. Immediately the patient had a mild epileptiform convulsion. An air- way was inserted and oxygen was administered by inter- mittent positive pressure ventilation. The fit lasted approximately 20 seconds and shortly after this spon- taneous respiration returned. The patient remained pink and the blood pressure was 140/80 mm Hg. The mother's pulse rate was 72 beats/min and the foetal heart rate was 140 beats/min. Consciousness returned in 2 minutes and at this time the patient appeared rational. A venous blood sample was taken 3 minutes after the onset of the convulsion for estimation of bupivacaine concentra- tion. The epidural catheter was removed and opiate anal- gesia was used for the remainder of the labour. At full dilatation of the cervix the foetal head was in the occipito-posterior position. Under general anaesthesia die foetus was found to have rotated to the occipito-anterior position and the baby was delivered easily using Neville Barnes forceps. The Apgar score at 1 minute was 10.