Some Suggestions for Simplifying Subcutaneous Tunneling

Abstract

To the Editor: In reference to the interesting letter of Balamoutsos et al. [1], we report our 15-yr experience involving more than 1000 oncology patients. Whatever the patient's life expectancy [2], we prefer the peridural or subarachnoid administration of opiates in an open system. A polyamide catheter, commonly used for peridural anesthesia, is tunneled for 4/5 of its length under local anesthesia using an average of 30-40 mL of bupivacaine 0.25% with epinephrine (5 micro g/mL) until it emerges from the skin of the infraclavicular fossa. The catheter is secured under the skin by a special methyl methacrylate button (Figure 1) placed into a subcutaneous pocket created on the posterior edge of the supraclavicular fossa according to a previously described technique [3]. To ease the subcutaneous transit of the catheter, we have devised and had manufactured a steel tunneling device that has all the advantages of those on the market, without their defects (large diameter, damage to tissues and vessels). This device is easy to guide, is ductile and easily follows the curve of the ribcage, is only slightly traumatic because it is of small caliber (internal diameter 16 gauge). Because the tip is rounded, it is not dangerous for the operator (our patients are sometimes positive for human immunodeficiency virus or for hepatitis B or C).Figure 1: The Figure showsthe Teflon cannula (its hub has been cut off), and the methyl methacrylate button has been placed on the peridural catheter to avoid its migration.The tunnelling device consists of a steel tube 35 or 45 cm long (Figure 2) in which is inserted a steel stylet that has a small but convenient handle. The rounded tip of the stylet protrudes approximately 1.5 cm from the end of the device (Figure 3). This tip passes easily at the subcutaneous level when there are no deep scars due to thoracotomy.Figure 2: The tunneling devices of 35 and 45 cm (internal diameter 16 gauge).Figure 3: Detail of the stylet tip.The tunneling device is easily guided and brought to emerge from a superficial incision along the projected path of the catheter traced beforehand with a dermographic pen. The stylet prevents the incursion of blood and lobules of fat during the progression. Dismantled into its two components, the device is easily cleaned and resterilized in an autoclave. We have used the same instruments for more than 12 yr without any problem. In a person of average height, we can complete the tunneling with only two passages. In the first, we bring the catheter up from the dorsolumbar zone to the shoulder using the long device (45 cm); in the second, supraclavicular passage, we complete the tunneling using a long intravenous Teflon cannula similar to that described by Balamoutsos [1]. This last emerges from the skin atraumatically with no need for incisions at the exit point. The exit point of the catheter is disinfected and protected by iodopovidone ointment, changed weekly. Experience leads us to prefer the Perifix polyamide catheters of B. Braun, Melsungen, Germany: their screw top holds perfectly for more than a year without glue. On its top we place an antibacteria filter, which has a perforable stopper to facilitate bolus injections. In conclusion, the advantages of our method are that the tunneling of 4/5 of the length of the catheter guarantees the sterility of the subcutaneous passage, that the catheter, taut between the shoulder and the rachidian entry point, does not kink even after notable thinning, and that the methyl metacrylate button blocks the catheter underneath the skin, preventing accidental withdrawal. It does not provoke sores or rejection. Further, it eliminates anchorage points that provoke local inflammation and suppurations that, on becoming detached, allow the catheter to withdraw. Felice Ramaioli, MD* D. De Amici, MD** Departments of *Anesthesiology and Intensive Care II and **Clinical Epidemiology and Biometry Instituto di Ricerca e Cura a Carattere Scientifics Policlinico S. Matteo; 27100 Pavia, Italy