Tel me something about catheter access for haemo dialysis..?

Answer 1

Catheter access, (called CVC - Central Venous Catheter), consists of a plastic catheter with two lumens or two separate catheters which is inserted into a large vein (usually the vena cava, via the internal jugular vein or the femoral vein) to allow large flows of blood to be withdrawn from one lumen, to go into the dialysis circuit, and to be returned via the other lumen.

They are usually found in two general varieties, tunnelled and non-tunnelled.
Non-tunnelled catheter access is for short term access (up to about 10 days, but often for one dialysis session only), and the catheter emerges from the skin at the site of entry into the vein.
Tunnelled catheter access involves a longer catheter, which is tunnelled under the skin from the point of insertion in the vein to an exit site some distance away. They are usually placed in the internal jugular vein in the neck and the exit site is usually on the chest wall. The tunnel acts as a barrier to invading microbes and as such tunnelled catheters are designed for short to medium term access (weeks to months only), as infection is still a frequent problem.

Venous stenosis is one of the serious problems with catheter access. The catheter is a foreign body in the vein, and often provokes an inflammatory reaction in the vein wall, which results in scarring and narrowing of the vein causing problems with severe venous congestion in the area drained by the vein and may also render the vein, and the veins drained by it, useless for the formation of a fistula or graft at a later date. Patients on longterm hemodialysis can literally 'run-out' of access, so this can be a fatal problem.

Catheter access is usually used for rapid access for immediate dialysis, for tunnelled access in patients who are deemed likely to recover from acute renal failure, and patients with end-stage renal failure, who are either waiting for alternative access to mature, or those who are unable to have alternative access.
Catheter access is often popular with patients, as attachment to the dialysis machine doesn't require needles.

Answer 2

To insert a catheter for haemodialysis requires a skilled doctor and a large vein.

The doctor will tend to use a large catheter - much bigger than the small ones you see in arms for "drips" - and will usually want to access the subclavian vein (under the clavicle) or the internal jugular vein (in the neck) - or sometimes the femoral vein (in the groin).

The doctor should check the indications for dialysis, any contraindications for this procedure and then consent the patient for the procedure - explaining what is going to happen.

The procedure (which may be different in different institutions) usually goes something like this (when I do it):

Correct Patient
Adequate Personnel (one assistant to help open sterile equipment)
Right Equipment (catheter kit (usually Seldinger type), syringes, needles, tying and dressing equipment)
Essential Drugs (local anaesthetic)

sterile technique - gown and gloves
prep and drape the area - clean with betadine or chlorhexadine or something similar

- identify the landmarks for the vein to be accessed
- apply local anaesthetic
- insert the seeker needle with syringe and access the vein
- when venous blood is aspirated then the syringe is disconnected and a Seldinger wire is inserted (some sets have special syringe that allows the wire to be inserted through the syringe) and the needle is withdrawn
- the skin is dilated with a dilator (or a tiny cut is made with a small blade) and the large bore catheter (permacath or vascath) is guided over the wire and into the vein
- the catheter is tied in place (1-0 silk usually) and a dressing applied
- procedure documented
- placement verified by X-ray if necessary

Answer 3

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