The efficacy of surgically placed epidural catheters for analgesia after posterior spinal surgery

Posterior spinal fusion for correction of scoliosis is a major procedure fo r which the provision of satisfactory, safe postoperative analgesia is ofte n a problem. One possible solution involves the placement of epidural cathe ters under direct vision by the surgeon at the end of the procedure, follow ed by an epidural infusion of local anaesthetic with or without an opioid. Despite its simplicity: this technique has not been reported as being consi stently successful. We report an observational study of the analgesia achie ved with surgically placed epidural catheters and of the reasons for the fa ilure of the technique. Fourteen consecutive patients undergoing posterior spinal fusion had epidural catheters placed by the surgeon and had radio-op aque dye injected down the catheter 15 min before their routine postoperati ve chest X-ray. Analgesia was assessed at 0, 6, 12 and 24 h after surgery u sing visual analogue scorns. Five patients had inadequate pain control; non e of these patients had dye visible in the epidural space. Seven patients h ad dye visible in the epidural space; all of these cases had satisfactory a nalgesia. In two cases, dye was observed in the paravertebral gutters; both of these patients had satisfactory postoperative analgesia. This small pil ot study suggests that correctly placed 'surgical' epidural catheters are c apable of providing good analgesia after posterior spinal fusion and that m isplaced catheters, seen in a large proportion of patients, are associated with inadequate analgesia.