arteriovenous fistulas for haemodialysis
AV fistula (AVF) is the preferred type of vascular access for patients undergoing haemodialysis.
- both the Renal Association and the National Institute for Health and Care Excellence guidelines proposes that
- 65% of all incident cases of haemodialysis (65% of all new starters each year) and 85% of all prevalent cases (85% of a unit's haemodialysis population) should receive dialysis through an arteriovenous fistula (1)
- adequate time should be allowed for maturation of the vascular access hence AVF needs to be planned at least one or two months prior to haemodialysis (2)
- arterial and venous diameters are predictive of AVF maturation - a vein diameter >2 mm and an artery diameter >1.6 mm on duplex ultrasound scan are considered to be adequate
AV fistulas are considered to be the best short, intermediate, and long term option for renal replacement therapy over other types of vascular access. Compared to catheters and synthetic grafts, it has:
- lower risk of infection - 10 times lower
- lower risk of thrombosis
- greater longevity of the access point
- greater blood flow volume
- shorter duration of dialysis (1)
AVF should be created as distal as possible in the non-dominant arm and moved progressively proximal and if unavoidable, moving to the dominant arm.
- National Kidney Foundation (NKF-K/DOQI) has recommended the following order of preference for the creation of AVF; forearm (radio-cephalic or distal AVF), elbow (brachio-cephalic or proximal AVF), arm (brachial-basilic AVF with transposition or proximal AVF) (2).
There are several types of arteriovenous anastamosis:
- side-to-end of the vein on the artery - most common type of anastomosis
- latero-lateral
- terminalized side-to-side
- side-to-end of the artery on the vein
- end-to-end (2)
Pre-existing severe peripheral vascular disease, cardiac failure, and amputation of the relevant arm are considered as potential (not absolute) contraindications for creating an AVF (1)
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