What are the precautions to be taken after AV fistula or graft?
- After the formation of the AV fistula or graft elevates the limb to avoid swelling.
- Keep the incision dry for 48 hours and do not soak or scrub the incision till healed.
- Avoid lifting weights over 7-8 Kg.
- Do not compress the site of surgery by recording blood pressure from that side.
- Report any pain, swelling or bleeding from the site.
- If there is prolonged pain, numbness, coolness or blueness of the fingers or hand please inform your surgeon and much of the blood is being diverted from the hand into the fistula. This is called ‘Steal Syndrome’.
- One must perform hand exercise to increase the flow of blood into the fistula. This is done by squeezing a softball with the hand with fistula.
- Grafts mature in 2-4 weeks but should be used after 6 weeks.
- Grafts have a greater chance to be infected.
- Grafts for 1-2 years which is less than fistulas which could last 3-7 years.
- Till the fistula or graft matures a catheter is used for dialysis.
What are the problems one could face after AV Fistula?
- Steal syndrome
- Blockage due to clotting
- Narrowing due to stenosis
- Aneurysm formation
What should I do to stay healthy?
It is important to protect your dialysis access. This is done by:
- Check often to make sure the fistula is working by feeling the vibration known as a thrill.
- Monitor the bleeding after dialysis. Should it continue for long take advice?
- Avoid carrying heavy articles in the hand with venous access.
- Do not sleep on the arm with access.
- Do not wear constricting clothing or jewelry on the arm with access.
- Do not allow anyone to draw blood or take blood pressure from that arm.
- Do not allow anyone to give injections into the fistula or the graft.
- Keep the site of the fistula or graft clean
- After each dialysis look for redness or swelling which are signs of infection.
- Do not apply any cream fo lotion over the site of the fistula or graft.
What are my choices to undergo dialysis and how do I decide?
The patient has basically three choices:
1. Peritoneal dialysis
2. Catheter placement
3. Vascular access surgery
How is the peritoneal dialysis (PD) catheter inserted?
- It is done under general anesthesia as a day case.
- The PD catheter is the length of a ruler and the width of a pencil.
- During surgery one end is placed in the peritoneal cavity and the rest of the catheter lies outside the abdomen though it is tunneled below the skin.
- There are two ways of placing the catheter – laparoscopic or surgical. In the former two toney incisions are made under general anesthesia – one for the scope and the second for the catheter. In surgery, an incision is made and the catheter is placed in the abdominal cavity. It is tunneled under the skin to avoid infection.
- Infection is prevented by using a tube with a valve at the end which is used to close and open the catheter during the exchange process to avoid infection.
How is the hemodialysis fistula made?
- One of your arteries is connected to one of your veins.
- The fistula takes 3-6 months to mature
- An ultrasound of the veins may be needed to see its size
- It is performed under local anesthesia and perhaps sedation
What are the post-operative precautions?
- You would have to elevate the limb to reduce the swelling
- You may need pain killers after the surgery
- To strengthen the fistula you may have to exercise the limb by a squeezing rubber ball.
What are the benefits of an AV Fistula?
- Low risk of infection
- Low risk of clot formation
- Performs better than grafts/
- Allows greater blood flow
- Lasts longer if cared for – even decades
What are the drawbacks of AV fistulas?
- Bulging veins at access sites
- Take too long to mature
- Rarely they do not mature
How are AV Grafts placed in hemodialysis?
- This is recommended of the veins are blocked or too small in caliber.
- A synthetic tube is inserted in your arm and connected artery to a vein
- These grafts can be used within 2 – 6 weeks.
How does one plan for vascular access?
- Preserve veins for vascular access well in advance when GFR is less than 30 ml/min.
- The preferred site is radio-cephalic AV fistula.
- Non-dominant upper limb must never be used for drawing blood or IV punctures.
- If the arm for the fistula has to be used then use the hand veins and sites are rotated frequently
- The preferred access is AV fistula, followed by AV graft and finally central venous catheters.
- Chances of infection are most in central venous catheters followed by AV Grafts and then AV fistulas.
- AV fistula has better survival than AV Graft.
- Studies show an equal survival on peritoneal dialysis and hemodialysis. Thus peritoneal dialysis is preferred to central venous lines.
- The preferred site is radio-cephalic followed by brachio-cephalic fistula.
- If not possible then brachio-basilic fistula is performed followed by transposition 6 weeks later.
- For AV Grafting the preferred site is loop radiocephalic graft or brachio-axillary graft. The least preferred site is the thigh grafts.
When are venograms recommended?
- Oedema in the limb here fistula is planned
- Accessory vein enlargement in any planned access site
- Differential extremity size if it is planned as an access site.
- Central line in a subclavian vein in the planned side
- Previous arm neck or chest injury or surgery on the venous system of the planned side.
- A pacemaker in the venous drainage of the planned side.
- Multiple previous accesses on the planned side.
What is the best timing for AV access, its placement, and its maturation?
- A fistula is advised when the GFR is 15-20 ml/min and there is a progressive renal disease.
- It is important to make the fistula 3-4 months before the anticipated use of the fistula
- AV grafting is recommended when it is not possible to use an AV Fistula and is done 3-6 weeks before the anticipated use.
- Permachaths are put immediately before the dialysis as they need no time to mature. However, there is a chance of infection, thrombosis, and dialysis inadequacy. The tip must be beyond the SVC in the right atrium which is confirmed by radiography. Insertion is guided by ultrasound to avoid complications.
- Subclavian access is used only when jugular access is not possible.
- Avoid subclavian or jugular catheters on the side AV fistula is maturing.
- The patients with chronic renal disease needing acute hemodialysis vascular access use percutaneously inserted catheters. They are inserted just before use.
- Femoral catheters must be at least 19 cm long to reduce recirculation. They have left so long as there are no complications.
- AV fistula maturation depends upon the size of the artery, the vein, and the cardiac output. The time of use depends upon clinical judgment.
How can we enhance the use of AV Fistulas?
- Arm and hand exercises by squeezing a rubber ball with a lightly applied tourniquet.
- Selective tying of the major veins side branches
- Rest till the swelling has resolved.
- AV Graft should not be cannulated till the swelling is reduced and the graft is palpable along its course. This takes 3-6 weeks
- Never cannulate a graft within 2 weeks of making.
- If the swelling does not respond to elevation or persists beyond 2 weeks of placement use venogram or non-invasive study to evaluate central veins.
How is the functioning of the vascular access monitored and maintained?
- Measure the access flow bimonthly in case of AV Fistula and venous pressure or access flow monthly in AV graft.
- Perform angiography of the fistula flow falls below 500ml/min and AV Graft below 650 ml/min
- Intra-access flow and monitoring changes in flow.
- Static venous pressure
- Dynamic venous pressure
- Slow flow venous pressure
- Using access recirculation measures one must be aware that the recirculation is abnormal and has to be investigated. Recirculation of > 5% using non-urea based measures or > 15% using urea-based methods significant and needs angiography.
- Unexplained reduction in the form of hemodialysis delivered.
- Persistent swelling of the arm with an AV graft.
- Prolonged bleeding after removing the needle or altered thrill in the graft.
- Increased negative arterial pre-pump pressure that prevents increasing to acceptable blood flow.
- Venography or Doppler ultrasound.
How are poorly functioning venous access managed?
Any finding of access dysfunction using any technique must be investigated by an angiogram and corrective measures are taken – angioplasty or surgery.
In the period before corrective measures can be undertaken because the dialysis circuit exceeds the access flow, access recirculation leads to inadequate dialysis. If this occurs then the dialyzer flow is reduced to below-measured access flow.