Most valid recommendations prefer the native AVF as a vascular access for chronic dialysis treatment [1-3]. However, the number of patients with tCVC is high and, depending on the source, accounts for up to 80% of patients initiating HD treatment [13-15]. The main complications associated with the use of tCVC are infections and thrombotic occlusions [16]. The problem of patency reduces the effectiveness/adequacy of dialysis, and both of these complications increase the morbidity and mortality of dialyzed patients [17]. The frequency of the bacteremia is reported with rates of 2.7 per 1000 catheter days in the first month of catheter use and 0.4 per 1000 catheter days for > 12 months [18]. The target should be the rate lower than 1 episode of CRBSI per 1000 catheter days [19]. In our study, all patients were newly enrolled in the HD program, and the bacteremia rate of less than 0.64 per 1000 catheter days is therefore quite satisfactory, although it is burdened with no primary endpoint. However, in the context of the results of other studies, tCVCs may be considered relatively safe [11-12]. On the one hand, this is in contradiction with general recommendations (try to avoid tCVC rather). On the other hand, it has already been mentioned that for some certain type of dialysis population tCVC is a better alternative [20-21]. These include, in particular, patients of advanced age with severe sclerotic lesion, often with relatively short life perspectives or even considering palliative nephrology care. Under these circumstances, it is certainly not appropriate to set AVF in advance for many months, but it is better to wait for further course. If necessary, for initiating HD treatment, tCVC is the best and often lasting solution. We think our results with low incidence of CRBSI further supports this approach.
An important part of tCVC care is an aseptic approach in general and local exit site care. The aim of catheter locks is to ensure the patency of tCVC at the time between HD and, as far as possible, to reduce possible infectious complications. In the context of these requirements, the composition of the locks has evolved over time. In the past, heparin was the most commonly used; in recent years, it has been seen to shift most often to citrate [10]. Higher citrate concentration (30%, 46.7%) were withdrawn by FDA for possible association with serious adverse effects, and citrate locks with the most commonly 4% concentration are currently used [22–23]. They appear to be safe and relatively inexpensive and have some antimicrobial activity [23–24]. For this reason, they are also the most recommended [25]. In the case of acute obstruction of tCVC, it is recommended to use fibrinolytic agent, e.g. rt-PA [3]. Thus, the question is whether regular fibrinolytic administration would further affect the malfunction of tCVC or the frequency of CRBSI. Because the major drawback of rt-PA is its high cost, it is usually used once a week. When compared to heparin locks, the beneficial effect of rt-PA administration was already shown [11]. In our study, we decided to verify the effect of rt-PA compared to citrate locks. However, during the 655 HD procedures in 18 patients, a significant difference was not found. The occurrence of malfunctions and afunctions was the same in both study arms. Using the linear regression, we found the length of interdialytic interval was the most important factor. The longer the interdialytic interval, the higher the risk of tCVC obstruction. And at the same time - if obstruction occurs once, the risk of every other obstruction is significantly higher.
A promising group for some time were locks containing antibiotic, but these are not yet generally recommended [26]. The main concern and problem are the risk of resistance. A certain alternative seems to be the lock that contains taurolidine. Taurolidine is an antimicrobial chemotherapeutic agent that acts through a chemical reaction with the microbial structure of the cell wall. It has an extremely wide microbial spectrum including methicillin- and vancomycin- resistant bacteria and unlike conventional antibiotics, the resistance has not yet been described [27]. However, the position of taurolidine on the field of catheter locks has to be verified by more prospective and randomized trials.
The weakness of our study is the fact that we have failed to include the required number of patients. We were confronted with strict exclusion criteria that eliminated most incident patients with tCVC. The second point was very low occurrence of primary outcome. On the other hand, we can say that the occurrence of CRBSI is low and tCVC is therefore relatively safe. They appear to be a good alternative to vascular access in patients, particularly with uncertain prognosis and exhausted own vascular system. This is in contradiction with common recommendations, but data from recent clinical practice tends to support this opinion.