What is AV Graft?

AV graft or Arterio Venous Graft means an artificial connection between arterial line and the venous line. We use an artificial hollow material to create the surgical connection between two vessels. Usually this connection is created in elbow pit.

When to use the AV graft?

As we mentioned earlier, Av graft is not the most effective method of permanent vascular access for haemodialysis. However in some special situations, it is the first choice as a vascular access for dialysis.

1. Patient with inadequate venous access.
2. Patient who need an access soon.
   
   
   

Advantages of AV graft

Can use for patient need urgent regular haemodialysis
When you use an AV fistula for dialysis, you may have to wait for another 3 -6 month to maturity of the fistula site.However Arterio venous graft do not take that much of time to initiation of the dialysis. Usually we can start the haemodialysis after 1 month of the surgery. This is due to the fast maturity of the graft site.

Can use in patients with small blood vessels
Formation of AV fistula is very difficult surgery. Especially it is difficult procedure in wrist area. This is because of the absence of the large blood vessels in this area. However Arterio Venous graft can be used even in patients with vascular issues.

Need only the local anesthesia
This surgery is done under local anesthesia. In addition it is performed as a day surgery. Therefore you do not need long hospital stay.

Disadvantages of Arterio Venous Graft (AV Graft)

1. Insertion of artificial material to body
   We use synthetic material to connect two blood vessels together. Therefore we have to insert this synthetic material to the fistula site.
   
2. Risk of closure
   Although the AV fistula is often last a long time, there is a high chance of AV graft to get blocked by frequent blood clots.
   
3. Risk of infections
   As we have placed a synthetic material in our body, it is often tend to get infected. Therefore careful handling is necessary.
   
   
   

How to prepare for AV graft

When you are diagnosed as having Chronic Kidney Disease (CKD), your nephrologist would discuss about the future treatment options with you. You need hemodialysis only if you become a patient with End Stage Kidney Disease (ESKD). However there may be some other instance you need a dialysis in an acute set up.

When your condition is getting worse you have to select a kind of option from Kidney transplant, regular haemodialysis, CAPD or no treatments. If you select to dialyze for long time, you need to select your vascular access for dialysis. As we already have discussed Arterio Venous Fistula (AV Fistula) is the most commonly used vascular access. However there are options like Arterio Venous Graft (AV Graft) and Permanent catheter. Your vascular surgeon will decide your mode of vascular access depending on your conditions.

What is better option between hemodialysis and peritoneal dialysis?

This is probably will do after a proper vascular mapping and physical assessment.
Then you will give a date for the surgery probably as outpatient setting.
After 2 – 4 weeks of surgery your vascular surgeon will allow you to puncture the fistula site.

How to handle the AV graft during haemodialysis

Whenever an AV graft or AV fistula is created it should be handle in a proper way. Unless the lifespan of the vascular access get reduced. Then we have to reconstruct the vascular access or we have to recreate a vascular access.

You can apply some local anesthetic medication like lignocaine to reduce the pain during puncturing of the AV graft. But usage of subcutaneous lignocaine can increase the site of punctures.

You should handle the AV fistula in a way that minimum infections would be entered. Proper hand washing and disinfectants may be helpful to reduce the number of infections. Povidone Iodine solution can be used to clear the skin around the puncture site of the fistula.

You can use the same way as the puncture of the AV fistula for dialysis. That is puncturing of two sites of vein, one close to the arterial connection and other one way from the arterial connection.
You will use 16G AV Fistula needle for the procedure.

At the end of the dialysis session, you have to stop the bleeding with moderate pressure around the puncture site.

Proper use of heparin during dialysis will reduce the unnecessary bleeding will preventing the unnecessary clots.

Related articles

1. Michael Allon MD, Charmaine E. Lok MD, MSc, FRCPC, in Handbook of Dialysis Therapy (Fifth Edition), 2017.
   https://www.sciencedirect.com/science/article/pii/B9780323391542000059
   
2. Michael Allon, M.D., University of Alabama at Birmingham, Vascular Access for Hemodialysis, UCSF Department of surgery, 2014.
   https://surgery.ucsf.edu/conditions–procedures/vascular-access-for-hemodialysis.aspx

What is AV fistula?

Arterio-Venous fistula (AV Fistula) is a vascular connection created between an artery and a vein. This need to be done by a surgeon specialized in blood vessels (Vascular surgeon). Usually your surgeon would select vessels around the left wrist (on non-dominant hand).

Types of AV Fistula

Usually we create AV fistula for dialysis in two major sites.

• Wrist (Radio – Cephalic fistula)
• Elbow pit (Brachio – Cephalic fistula)

Radio – cephalic fistula

Radio cephalic fistula is the most difficult AV fistula to create. This is due to the small size of the radial artery and the cephalic vein around the wrist. Your vascular surgeon will stich the artery and veins to make the AV fistula for dialysis.

As a result of the Radio – Cephalic Fistula, there is a permanent connection between this two vessels. Therefore the high blood pressure of the radial artery cause high blood flow to the cephalic vein. So the cephalic vein get thicker.

Bachio – Cephalic fistula

When we need to create an AV fistula for the chronic dialysis, we often use vessels around the wrist. But as mentioned above it is not an easy surgery. In some patients distal AV fistula get failed. In such situations, we need to try for an AV fistula around the elbow fit.

Your vascular surgeon will connect the basilica artery in the medial side to the cephalic vein in the lateral side at the elbow pit. Then it create a vascular connection between these two arteries.

How to prepare for the AV fistula surgery?

Usually we create AV fistula for dialysis even before 6 months of 1st dialysis. Usually patient is counseled for the method of renal replacement therapy when he turns into the end stage kidney disease.

You will be referred to a specialized vascular surgeon for Av fistula creation.
When you meet your vascular surgeon, he will access some of your general conditions in addition to the vascular issues. This is for the preparation of the surgery.

Then he will perform a vascular mapping to select the best vascular access to create AV fistula for dialysis. As mentioned above, most preferred site of the surgery is the wrist. But if it is not well developed, He will select the Bachio – Cephalic access.

The AV fistula surgery is perform under general anesthesia. But in some stations they are doing it under local anesthesia or nerve block. This is often a day surgery.
After the surgery, your surgeon will review you for the maturation of the Av fistula around 3 months. Until that you need to have some exercise to improve the maturation of the AV fistula.

How to use AV Fistula for dialysis

When we discuss about the haemodialysis, the AV fistula is the most important part of the Haemodialysis procedure. Some says it is the lifeline of the CKD patients.

Assessment of the AV Fistula

The Arterio venous access should be properly maintained during dialysis. You need to continue adequate amount of wrist / arm exercises to improve the quality of AV Fistula.

Usually the vascular surgeon need to access the maturity and usability of the AV fistula for dialysis. If it is not adequately grown, you have to give some adequate exercise before the 1st puncture of the AV fistula site. In addition to the maturity there are some other factors to be assess by the vascular surgeon before allowing the usage of AV fistula for hemodialysis.

Puncturing of AV fistula for dialysis

After the proper assessment, a dialysis nurse or a dialysis technician will do the 1st puncture of your AV fistula for the initiation of the dialysis. The nurse will connect 2 AV fistula needles to your AV fistula site atleast 5 cm away from the surgical site. Usual gauge of the puncture needle for initial dialysis is 17G needles. One needle is inserted to the arterial side of the AV fistula. Then another needle is inserted to the venous side of the fistula.

The arterial needle will be used to drag blood from the body. Then the blood will be going through the dialysis machine. Then venous needle will be used to insert the cleared blood into body.
After the dialysis session, dialysis nurse will remove both needle with adequate pressure to avoid bleeding.

Your dialysis nurse will repeat this procedure in each dialysis session. However when your AV fistula is getting larger, you can select 16G AV fistula needle for the puncturing of AV fistula.

How to pain relive during fistula puncturing?

Each time when you are undergoing haemodialysis, you have to undergo repeated AV fistula site puncturing. Therefore you can use local anesthetic application or spray which include lignocaine like substance.

What are the advantages of AV fistula than other vascular access for dialysis patient?

AV fistula is the most effective vascular access. It has less complication during dialysis. Therefore it is often superior to all other methods like, AV graft, Permanent catheter or temporary catheter.
The benefit of AV fistula is followings;

1. Less chance to get clots.
2. Less risk of infections.
3. No autoimmune mechanisms as it use own vessels.
4. Can use as a permanent access as it serves longer than any of other forms.
5. Done as outpatient surgery.
6. Blood supply is very high.
   
   
   

What are the disadvantages of AV fistula for dialysis?

Even though AV fistula is superior to all other methods, still it has several disadvantages.

1. Take some time to mature. Therefore may have to use other temporary methods as vascular accesses.
2. This is a difficult surgery. We can’t perform it in some patients with small veins and arteries.
3. There are cosmetic issues.
4. Maturation need daily regular exercises.

Reference articles

1. Lee, C.; Toppin, J.; Snyman, A.; Oreopoulos, G.; Bhola, C.; Djaiani, G. Different anesthetic techniques for arteriovenous fistula formation: Early and late fistula failure rates, European Journal of Anaesthesiology: June 2011 – Volume 28 – Issue – p 121-122
   https://journals.lww.com/ejanaesthesiology/fulltext/2011/06001/different_anesthetic_techniques_for_arteriovenous.388.aspx
   
   
2. Increasing the Use of Arteriovenous Fistula in Hemodialysis: Economic Benefits and Economic BarriersDonald Schon, Steven W. Blume, Kimberly Niebauer, Christopher S. Hollenbeak, Gregory de LissovoyCJASN Mar 2007, 2 (2) 268-276. 
   DOI: 10.2215/CJN.01880606