Hemodialysis catheter placement
For a patient whose kidneys have failed, venous access or access to the blood system must be established and maintained for dialysis treatments. The access should be available for immediate use and have minimal complications in the short term (from days to weeks).
The main categories of catheters available for hemodialysis vascular access include non-tunnelled and tunnelled catheters. Non-tunnelled catheters are most often used when there is an immediate need for hemodialysis (e.g. acute kidney injury). If dialysis may be needed for more than a week or for patients with chronic kidney disease who require dialysis but do not have a functional permanent vascular access, a cuffed, tunnelled catheter should be used instead.
General information about catheters
Dialysis catheters usually have at least two lumens attached to two ports (blue and red). By convention, the red port identifies the “arterial” lumen that draws blood from the body, and the blue port identifies the “venous” lumen for the return of blood from the dialysis machine to the patient. The lumen of a dialysis catheter has a larger diameter in order to provide a high rate of flow, which is essential in the dialysis process.
As mentioned above, there are two main types of catheters: tunnelled and non-tunnelled.
Non-tunnelled catheters are designed for short-term use only and therefore should not be used routinely in the home or outpatient setting. They are fixed in place at the site of insertion with the catheter and attachments protruding. There are many types of non-tunnelled catheters available, each composed of different materials. The validity of these catheters varies according to insertion site. Mechanical malfunction and infectious complications are the principle reasons for removing a non-tunnelled dialysis catheter.
Tunnelled catheters are primarily used for intermediate or long-term hemodialysis vascular access. This type of catheter is passed under the skin from the insertion site to a separate exit site. The catheter and its attachments emerge from underneath the skin.
Although in the case of chronic hemodialysis patients the preferred access is an arteriovenous access (AV), some patients are poor candidates for AV access creation and therefore require a long-term catheter. A wide variety of tunnelled catheters are available, and they are associated with lower rates of infectious complications than non-tunnelled catheters.
Catheter placement and maintenance
Catheters for dialysis access are placed in a similar manner to central venous catheter placement for other conditions. They can be inserted into any of the central veins, such as the internal jugular vein, the femoral vein, or the subclavian vein. The right internal jugular vein is the preferred vein for hemodialysis access.
For non-tunnelled dialysis catheters, local anesthesia and ultrasound guidance should be used, and the catheter can be placed at the bedside or in a procedure room. Due to their larger radius and the need to tailor the catheter for proper positioning, tunnelled catheters are almost exclusively placed using ultrasound and fluoroscopic guidance (imaging technique that uses X-rays to obtain real-time moving images of the interior of an object), with local anesthesia, either with or without sedation, and in an appropriately equipped operating room.
The catheter insertion and exit sites will take approximately two to three weeks to heal.
The catheter should be handled with the proper and correct hygiene of both the patient and the medical staff. Before connecting the catheter to the dialysis machine, it should be flushed with a saline solution; at the end of the dialysis treatment, the catheter should be flushed with anticoagulant flush solutions, using heparin as the most common solution. Applying these steps may reduce the likelihood of thrombosis formation.
Main complications of catheters
A variety of complications are associated with the placement and use of hemodialysis access catheters, including those associated with catheter insertion and longer-term (>1 week) complications such as catheter malfunction, central vein stenosis or thrombosis, and catheter infection. Central vein stenosis/thrombosis is a complication of all central venous catheters but may be more prominent with hemodialysis access due to the larger diameter of the catheter relative to the cannulated vein, repeated catheterizations, and turbulent blood flow during dialysis.
Infectious complications of hemodialysis catheters include local exit site infection and systemic bacteremia.
The risk of infection for tunnelled catheters is significantly lower than for non-tunnelled catheters. Prevention of infection involves strict adherence to proper placement technique and optimal catheter management.
Due to the high rate of infection and morbidity alternatives to catheters should be used as means of permanent vascular access. In some situations, however, this is not an option. Prolonged use of hemodialysis catheters is justified when needed as a bridge device while awaiting arteriovenous access maturation or transplant for patients who have exhausted other forms of access and for whom the risk of complications of arteriovenous access is excessive.
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