To the Editor:--A lumbar spinal fluid drain commonly is inserted in an attempt to improve spinal perfusion pressure during thoracoabdominal aneurysm surgery. [1-3]It is important to pass these drains as atraumatically as possible. However, insertion of such catheters can be difficult.
We use a kit (Codman, Johnson & Johnson, Waltham, MA) that contains a 14-G Tuohy needle through which a drainage catheter is inserted. The catheter is soft and flexible, but no guidewire is provided. Insertion of a lumbar drainage catheter into children, most commonly for neurosurgical procedures, often can be accomplished without use of a guidewire. However, in adults, the lack of a guidewire complicates and may preclude placement, because it may be difficult to pass the flexible catheter through the needle.
We have found the use of a 45-cm, 0.021-inch pediatric central venous catheter guidewire (Walrus Medical, Parameters, Woburn, MA) to be helpful in the placement of these catheters. The straight end of the wire is inserted into the catheter until the tip of the wire is just at the drainage perforations at the end of the catheter. At this depth of insertion, the J-end of the wire just protrudes from the proximal end of the catheter (Figure 1), which helps to monitor the depth of wire insertion. The increased stiffness this imparts to the catheter permits the drain to pass readily through the needle. We prefer the 0.021-inch wire rather than a 0.025-inch wire, because it sometimes is difficult to remove the tightly fitting 0.025-inch wire without removing the catheter; and there is the danger of the catheter becoming damaged by the tip of the wire. Similarly, to avoid injury to the catheter, we also recommend withdrawing the Tuohy needle from the patient before removing the wire. We have abandoned the use of wires from epidural catheters. These wires are thinner and do not fit snugly into the catheter, which may slide back over the wire during insertion.
The use of a guidewire during lumbar drain insertion allows the possibility of guidewire-induced injury to intrathecal structures. However, as described above, the wire is positioned so that it does not reach the tip of the catheter. This potential risk must be balanced against the potential benefit of decreasing the incidence of paraplegia after thoracoabdominal aneurysm surgery through use of a lumbar drainage catheter.
Kenneth J. Holroyd, M.D., Assistant Professor.
William T. Merritt, M.D., Associate Professor, Anesthesiology and Critical Care Medicine, Tower 711, Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, Maryland 21287.
(Accepted for publication April 29, 1995.)