Morphology of Peritoneal Dialysis Catheter Tunnel : Macroscopy and Light Microscopy

Abstract

There is scanty knowledge of the morphology of peritoneal dialysis catheter tunnels in humans, even though such knowledge may impact on peritoneal catheter design, implantation and postimplantation care. Past descriptions of catheter tunnels are based mainly on data from animal experiments. Based on these data, it has been assumed that epidermal spreading is inhibited by collagen fibers ingrown into the cuff. Our preliminary investigation indicated that this may not be the case in humans and led us to study catheter tunnel morphology in more detail. Eighteen catheter tunnels (2 -Smm of tissue around the catheters) were removed in 17 peritoneal dialysis patients. The catheters were inserted 30 to 2013 days prior to removal (median 366 days). The catheters were removed electively or because of infectious or noninfectious complications. Contrary to the observations in animals, in only 1 case did epithelium extend to the cuff with only a minimal amount of granulation tissue present at the end of a 9 mm long sinus tract. In the remaining cases, the leading edge of the epithelium always met granulation tissue 1 −14 mm from the exit, and the cuffs were found 8 33 mm from the exit. In tunnels older than 197 days, dense fibrous tissue was ingrown into the cuffs, and a dense fibrous capsule surrounded the cuff. The uninfected intercuff segment formed a pseudosheath, indistinguishable from a tendon sheath or synovial membrane. Infection in the catheter tunnel propagates through the part of the cuff adjacent to the tubing inside the capsule, suggesting that the cuff per sedoes not constitute a major barrier for spreading infection. This observation, by exclusion, infers that the beneficial role of an external cuff in decreasing exit infections is by providing firm anchorage of the catheter resulting in restriction of its piston like movement and thereby minimizing trauma and inward conveyance of outer sinus tract flora.

Peritoneal Dialysis Catheter Exit Site Infections: Prevention, Diagnosis, Treatment, and Future Directions

“…Tenckhoff challenged Hall's hypothesis, citing his experience with peritoneal catheters (60), which lasted for many years without cuff extrusion. Our recent study confirms Tenckhoff's premise, since in the majority of patients epidermal cells do not attach to the cuff (24).…”

“…As mentioned previously, the tissue ingrown into the cuff does not seem to constitute, per se, a critical barrier to the spread of infection (24). It seems that the basic benefit of the external cuff in infection prevention is gained by anchoring the catheter, resulting in restriction of its pistonlike movements, thus decreasing transport of bacteria into the sinus.…”

“…During the healing process part of the granulation tissue is gradually resorbed and replaced by fibrous tissue. The fibrous tissue and part of the granulation tissue are covered with epidermis (24). Impaired nutrition, diabetes mellitus, uremia, and corticosteroids are all known factors that decrease wound healing by decreasing fibrosis (38).…”

“…A detailed description of peritoneal catheter tunnel morphology has been published elsewhere (24). In uninfected peritoneal dialysis catheter tunnels the epithelium covers only the external part of the sinus tract, while the deeper part is covered with granulation tissue.…”

Inflammatory Reaction to Fabric Collars From Percutaneous Antennas Attached to Intracoelomic Radio Transmitters Implanted in Harlequin Ducks (Histrionicus histrionicus)

“…In humans with implants, collars are presumed not to be a barrier to infection but rather to act to stabilize the implant, thus preventing the pistonlike movement of percutaneous components that would tend to spread infection deeper into tissues. 31 Percutaneous devices that clinically appear free of complications often have evidence of inflammation and infection when examined histologically. 30 The mammalian tissue response to implanted foreign material, such as prosthetic breast implants, involves a chronologic progression: formation of fibrous scar tissue, histiocytic inflammatory response, giant-cell reaction, synovial-like metaplasia, and calcification.…”