Central Venous Catheters as Access for Hemodialysis
Acute dialyses, e.g., in the context of multi-organ failure, require an uncomplicated and rapid establishment of a large-lumen venous access. In this area, non-tunneled acute catheters are the dialysis access of first choice, which are primarily placed in the right internal jugular vein or also on the left. In immobile patients, access via the femoral vein is also considered. The subclavian veins must be absolutely avoided as access routes in all potential long-term dialysis patients, because large-lumen catheters can lead to central venous stenoses, which complicate or make impossible the further care of patients with AV fistulas [1-4].
When inserting the large-lumen catheters, an ultrasound examination of the large veins should in any case precede immediately [5, 6, 7]. In difficult conditions, the vein can also be punctured under real-time ultrasound conditions. A post-interventional X-ray check is mandatory.
The infection rates of non-tunneled dialysis catheters are approximately 6 to 10 treatment-requiring bacteremias per 1000 treatment days. The infection rate increases significantly with a dwell time of more than 2 to 3 weeks [8]. Infection rates with tunneled catheters with cuff are significantly lower at 2 to 3 bacteremias per 1000 treatment days. For this reason, in case of longer dwell time, a switch should be made to the less infection-prone tunneled dialysis catheter with cuff.
The German dialysis access recommendations indicate the indication for permanent dialysis via a tunneled catheter "as a last resort, if no other permanent access or no peritoneal dialysis is possible" [9].
The most common indication for tunneled dialysis atrial catheters is a need for dialysis for more than 3–4 weeks in the absence of shunt possibility and absence of possibility for peritoneal dialysis (PD). Further indications are a planned living donor transplantation, which requires only a dialysis duration of a few weeks. Patients in whom an AV fistula on the arm and leg is not possible due to steal syndrome should also be provided with a tunneled atrial catheter if PD is not possible. Severe heart failure with an ejection fraction of less than 25–30% also represents an indication for the implantation of a tunneled atrial catheter if PD is not possible.
As a rule, the implantation of central venous dialysis catheters is performed using the Seldinger technique under local anesthesia. A venesection is only required in a few exceptional cases.
Implantation sites for tunneled dialysis catheters are primarily the right, but also the left internal jugular vein. When implanted in the right internal jugular vein, flow problems occur less frequently than at all other implantation sites [10]. The subclavian vein is prohibited in cases where further shunt care is still planned, especially since it is thinner-lumen than the proximal jugular vein and venous thrombi in the subclavian are more common. In principle, implantation via the femoral vein or via translumbar and transhepatic accesses is also possible, although the functional duration of these accesses is significantly limited [11, 12, 13].
The correct position of the catheter tip is essential for the flow behavior of the catheter and should be at the transition of the vena cava to the right atrium or directly in the right atrium. For the correct positioning of the catheter tip and to avoid other complications (e.g., kinking of the catheter in the tunnel), fluoroscopy is absolutely necessary. It should also be noted that the catheter tip often migrates somewhat cranially in sitting patients during dialysis, which is why the tip should be placed somewhat deeper during implantation in the supine position [14].
In the long-term course, thrombi can form inside and outside the catheter lumen. Thrombi inside the lumen are to be prevented by so-called "lock solutions" between dialysis sessions. Acute occlusions can often be resolved by the administration of thrombolytics [15], and regular application of thrombolytics once a week is also said to be useful [16].
The increased mortality of dialysis patients with permanent dialysis catheters is mainly due to severe infections (endocarditides, spondylodiscitides). In addition to perioperative antibiotic prophylaxis (e.g., first-generation cephalosporin) and sterile implantation technique, nursing catheter management (strict hygiene protocols) is of high importance [17].