**9. Tunneled catheter complications**

Early or late catheter dysfunctions are the functional complications of TCs. Kinking and unsuitable positioning of the catheter tip may be the cause of early dysfunction and can be managed under fluoroscopic guidance. Around or at the catheter tip, fibrin sheaths and thrombi can be formed constituting late causes of failure. Balloon angioplasty can disrupt fibrinous sheaths, improving flow through a new catheter in the same location. Valliant et al. [236] have demonstrate in their study that there is no significant increase in bacteraemia and subsequent catheter dysfunction rates after fibrin sheath disruption by balloon procedure compared to simple over the wire exchange. Symptomatic occlusions of the central veins usually require the removal of the catheter and system anticoagulation and must be weighed in the context of a continued need for dialysis and other available access options. Yoon et al. recently referred a novel two-stage hemodialysis reliable outflow (HeRO) graft implantation technique that avoids the use of a femoral bridging hemodialysis catheter in internal jugular vein (IJV) catheter-dependent patients with contralateral central venous occlusion and thus lowering the risk of infection related to a femoral catheter [237]. The use of catheter is related to a higher incidence of infection and could compromise dialysis adequacy [238, 239]. Catheterrelated infections (CRI) are linked with increased all cause morbidity and mortality. The 8– 10% of MRSA bacteraemia in the UK occurs in patients receiving long-term hemodialysis. It appears that the catheter locking with appropriate antimicrobial lock solutions (ALS) decrease the infections' incidence in HD patients [180, 240, 241]. It seems that prophylaxis with genta‐ micin of the catheter lumens reduces bacterial infection morbidity and mortality-related bacteremia of catheter without obvious bacterial resistance, making such use advisable [242]. Even taurolidine–citrate–heparin catheter lock solution reduces staphylococcal bacteraemia rates in HD patients [243] and improves the inflammatory profile in HD patients with TCs [244]. Del Pozo et al. [245] in their prospective study showed that an evaluation of tunneled catheters with intracatheter leukocyte culture helps in the early colonization of HD catheters, giving the possibility to eradicate biofilm without the removal of catheter. Recent studies have demonstrate that the "shower and no-dressing" technique appears to be a safe TC option that improves quality of life [246, 247], although there is skepticism and uncertainty about the appropriate dressing [248].

#### **10. Final conclusions and remarks**

Unfortunately, there are no revolutionary changes in the field of vascular access for hemo‐ dialysis in the last years. According to the guidelines, AVFs are still the best choice. Luckily, AVGs' survival has been increased, but still TCs are used in a great portion of ESDRD patients. As a result, humerobasilic and radiocephalic AVFs are the two VA types with the most functioning longevity. However, AVFs' primary patency rates at 1 year vary considerably between USA and Europe. Hemodialysis patients with AVF seem to have lower mortality.

The incidence of AVFs has been effectively increased since the "fistula first" has been devel‐ oped, although it is accompanied with an increase in TCs.

AVGs as a second choice remain a good solution for patients without the possibility of AVF and the survival of grafts has been improved.

TCs seem to be a new reality in most American and European dialysis units because of the increase of number of elderly patients and with heart failure. Early referral to nephrologists and patient's education has an important role for a successful VA.

Additionally, the cannulation of VA is a crucial part of its management in HD patients and the proper use may improve the survival of VA.

Summarized from the international literature and our experience, when there are suitable vessels, the creation of AVF is of top priority. When this is not feasible or there is an AVF failure, AVGs or TCs are the first choice alternative or the second best, respectively. Female and old patients are more likely to initiate HD treatments via TC. A well-matured and functioning permanent vascular access is of great importance for its longevity and thus early referral to a nephrologist is mandatory.
