Tunnel exposure is a rare PD catheter-related complication. Our study included the largest number of cases with PD catheters complicated by tunnel exposure to the best of our knowledge. In all except one patient presenting with extensive infection, we attempted revision with partial external cuff shaving and creating a new tunnel without catheter change. The catheter salvage rate was 72.7%.
A previous study presented a patient with tunnel exposure caused by infection, and the catheter was removed due to severe infection . Two studies showed two patients with tunnel exposure without a definite infection. One of the two cases was treated using excision of skin and subcutaneous tissues around the exposure site and a simple suture without manipulating the external cuff and the exit site [4, 6]. Figure 1A and B show typical skin changes around the tunnel before and after tunnel exposure, including hyperpigmented and indurated skin lesions. Figure 1 presents a patient who had developed tunnel exposure three months after the presentation of the skin change. Our study did not define whether the primary cause of tunnel exposure in all cases was tunnel infection or pressure of PD catheter against soft tissues, regardless of infection. However, we treated 11 subjects using the same revision procedures, and 3 patients without infection signs did not have additional complications after revision.
Tunnel exposure can be developed by sustained pressure of the PD catheter to the surrounding tissues and/or posterior tunnel infection. Therefore, prevention or treatment of the exit-site and/or tunnel infection and decreasing the pressure on the subcutaneous tissues/skin through the tunnel may be an important step in preventing tunnel exposure. First, to decrease the exit site and/or tunnel infection, recent guidelines recommend cleaning and/or topical application of antibiotic ointment to the exit site, frequent inspection of exit site, and proper treatment using antibiotics for infection symptoms or signs . Second, decreasing the pressure on the subcutaneous tissues/skin through the tunnel would help prevent tunnel exposure. The catheter segment between the two cuffs can be prone to the pressure of the subcutaneous tissues/skin for the two cuffs swan neck catheter. Therefore, it can be useful to embed sufficient subcutaneous tissue above the catheter segment between two cuffs, including a bending site in especially thin patients without sufficient subcutaneous tissues. A previous study evaluated the risk factors for abdominal wall complications, such as peritoneal leak or hernia, in PD patients, and these factors may be associated with tunnel exposure as a complication . Our cases were not highly prevalent for these risk factors, but interpretation of our results should be carefully performed owing to the limitations of the small sample size and retrospective study design.
Tunnel exposure to the PD catheter is a rare complication. There are few studies regarding the proper management of tunnel exposure or alternative treatment options owing to the rarity of this complication. Most centers may perform catheter removal and reinsertion of a new catheter for this complication, which is the standard treatment for tunnel exposure. However, the procedure is relatively time-consuming, and psychological resistance may exist in some patients. Some patients may want to transfer to HD, as they misunderstand tunnel exposure as a severe complication requiring surgery. Furthermore, catheter replacement could require a new incision for the new PD catheter insertion, which may waste a new PD catheter reinsertion site in the absolute indication of PD catheter removal. In addition, the procedure needs to be performed in the operating room owing to the exposure of the intraperitoneal cavity. Our study is meaningful in presenting an alternative or bridging method for treating tunnel exposure in the PD catheters. Nevertheless, our procedure does not completely exclude infectious materials in the original catheter segment, which is associated with complications of infection after the procedure. Although our patients who underwent revision used fully original catheters, partial replacement of the catheter segment, as described in previous studies, could be another option for decreasing recurrent infection after revision for tunnel exposure [11,12,13]. Patients with a high risk for recurrent infection should consider catheter removal and reinsertion; however, those with low or moderate risk for recurrent infection may consider revision with or without partial replacement of the catheter as an alternative option for tunnel exposure. Although there were no definite guidelines that could have been used to define a high risk of recurrent infection after revision for tunnel exposure, those with close distance between the exposed/infectious lesion and internal cuff or new tunnel, infection by invasive organisms, such as gram-negative organism or fungus, simultaneous peritonitis, and extensive infection can be considered at high risk of recurrent infection after revision operation. If there is no evidence of infection, excision of the adjacent tissue around the exposure and suturing without manipulation of the external cuff may be sufficient. In addition, for all cases, the use of antibiotics is essential during the period before and after revision or removal.
Tunnel infections can precede or coexist with tunnel exposure. Early identification and treatment for infections at the skin or subcutaneous tissue around the catheter can be helpful in preventing tunnel exposure or decreasing complications after revision. Furthermore, some preventive interventions, such as glycemic control, mupirocin application for the nasal carriage of Staphylococcus aureus, exit-site care in a clean environment, and avoidance of injecting insulin or erythropoiesis-stimulating agents around the catheter could be recommended in clinical practice .
Our study has some limitations. Our study was of a retrospective study design, and data were collected at a single center over a long period owing to the rarity of this complication. In particular, data collection over a long period can be associated with differences in treating physicians, protocols for exit-site care, or the amount of clinical data collected from each case, which would lead to performance or selection biases. Therefore, the results of our study should be carefully interpreted, and the generalizability of our results is limited. In addition, our study did not compare various interventions according to the status of tunnel exposure. Future large scale studies are warranted to overcome these limitations.
In conclusion, the present study demonstrated that catheter revision performed by nephrologists could be a valuable alternative for original catheter salvage before considering catheter removal in tunnel exposure management.