A Simple and Reliable Method of Subcutaneous Tunneling of Epidural Catheters

Abstract

To the Editor: Epidural opioid administration for the treatment of chronic pain is becoming increasingly popular. Practitioners are often frustrated when catheters are dislodged due to patients' movements during daily or nursing care. Methods to prevent this problem include subcutaneous tunneling and fixing the catheter with sutures [1], use of silicone tubes [2], and use of double-stick disks [3]. In our hospital, to achieve greater safety and convenience in patients' daily activities, the following simple technique for subcutaneous tunneling is used. Regardless of the site of pain, all catheters are inserted at an interspace between the 2nd and the 5th lumbar vertebrae. Patients are in the sitting position and the skin is prepared and draped in a standard fashion. The site of the needle insertion and the skin along the tunneling line are anesthetized with an average of 20 mL of lidocaine 1%. A 16-gauge Tuohy needle is introduced using the loss of resistance technique, and the epidural catheter is inserted and the Tuohy needle removed. The catheters are tunneled stepwise subcutaneously to the anterolateral aspect of the chest wall at the anterior axillary line. For tunneling, a 16-gauge Abbocath (Abbott Laboratories, Chicago, IL) intravenous catheter is used. The Teflon cannula is removed, the hub is cut and discarded, and the cannula shaft is threaded back over the stylet Figure 1. The Abbocath needle, prepared as described, is inserted from the perforation point of the Tuohy needle Figure 2. This is done easily, as the Tuohy needle is wider than the corresponding catheter and there is room to insert the Abbocath needle without damaging the epidural catheter. For more safety, the entrance hole can easily and safely be widened by puncturing the skin twice just next to the Tuohy needle, before its removal, with an 18-gauge needle.Figure 1: Preparation of the Abbocath T intravenous cannula for subcutaneous tunneling.Figure 2: Insertion of the Abbocath T intravenous needle at the same site as the Tuohy needle entrance.The Abbocath needle with the cannula shaft is advanced until the tip of the needle emerges at a distance of 10-12 cm from the entrance point. The stylet is withdrawn, and the Teflon cannula shaft is used as an introducer. The midline end of the cannula is held firmly and the epidural catheter is passed through it Figure 3. When the epidural catheter emerges from the end of the cannula, both catheter and cannula are withdrawn. At this time, the midline end of the epidural catheter is held firmly with one hand to avoid kinking or accidental withdrawal while, with the other hand, the introducer and the catheter are pulled carefully and steadily from the lateral exit until the catheter is within the tunnel, no longer protruding from the entrance site in the midline. This procedure is repeated once or twice, each time ensuring the catheter's patency with 2 mL of normal saline, until the catheter finally emerges onto the anterolateral chest wall.Figure 3: Safe advancement of the epidural catheter through the cannula.The visible part of the epidural catheter is covered with Primapore 12 times 8.25 cm (Smith and Nephew, Herts, UK). A Millipore flat filter (Perifix; B. Braun, Melsungen, Germany) is attached at the free end of the catheter. It is suggested never to try to create a tunnel longer than 12 cm, as the cannula shaft's length is 14 cm Figure 1 and there is always the danger of losing it under the unfolded skin. The method has been used during the period 1992-1994 in 151 cancer patients with chronic and intractable pain. Of the 151 patients, 123 had only one epidural catheter until they died, 25 had two catheters, and only 3 patients had three catheters. All the patients had satisfactory pain relief until the end of their life. Mean duration of implantation was 59.0 +/- 58.8 (mean +/- SD) days, with a range of 9 to 674 days. Infection of the skin at the exit site was observed in five patients. All of them were treated successfully by removing the catheter and administering antibiotics. There were no signs of epidural space or systemic infection. Five patients developed epidural skin fistulae, which allowed a slow leak of the administered solution at the anterolateral exit of the catheter. The catheters were removed and the fistulae closed within 7 to 10 days. Having used this method for 4 years, we recommend it as a simple, easy, reliable, and inexpensive method for subcutaneous epidural catheter tunneling. Nicolaos G. Balamoutsos, MD Theodora N. Sfakiotaki, MD Symela P. Antoniadou, MD Intensive Care Unit and Pain Clinic Theagenion Cancer Hospital Thessaloniki, Macedonia, 546 39 Greece