British Journal of Anaesthesia 1995; 75: 666–669 Removal of lumbar extradural catheters

Sir,—Morris has suggested [1] that removal of a fixed extradural catheter may be facilitated by placing the patient in the original insertion position. I recently experienced a case where this recommendation was unhelpful. I was asked to assess a 73-yr-old patient who appeared to have an obstructed extradural catheter after a total hip replacement. The extradural space had been identified earlier at L3–4 via the midline approach with the patient in the left lateral position, and a 16-gauge catheter advanced without any difficulty. The extradural catheter had not posed any peroperative problems and had been providing excellent postoperative analgesia. My attempts to flush the catheter failed, and as there was no apparent cause for the obstruction, I decided to remove it and opt for patientcontrolled analgesia. However, removal in the left lateral position proved impossible. It was only when the patient had been sat forward with his lumbar spine maximally flexed that the catheter could be withdrawn easily. Close inspection of the catheter revealed a kink at the 5-cm mark, possibly where it had been caught between adjacent laminae. I would suggest that resistance to withdrawal of an extradural catheter should be managed by adjusting the degree of spinal flexion until a position is found where a minimum of force is required to facilitate removal. This may not necessarily be the original position in which the extradural catheter had been inserted. I. W. CHRISTIE Royal United Hospital Bath