The Arteriovenous Fistula
November 28th, 2019
Overview
An anastomosis between an artery and vein in the arm, created in order to dilate the vein for use in haemodialysis.
Look For
- Location of fistula - radiocephalic (forearm) / brachiocephalic (AC fossa), upper arm transposed basilic fistula
- Skin - rash, depigmentation, scars, ulceration
- Inflammation - erythema, swelling, tenderness
- Distal ischaemia - pain, pallor, pulselessness, paralysis, paraesthesia, poikilothermia Steal syndrome - vascular insufficiency
Feel For
- Consistency - soft, easily compressible
- Thrill - soft, continuous palpable thrill
- Hyperpulsatility - outflow obstruction
Auscultate For
- Normal bruit - soft, low-pitched hum
- High-pitched bruit Stenosis
Augmentation Test
Test For
- Inflow stenosis
How to Perform
- Use a finger to occlude outflow from the fistula a few centimetres from the anastomosis.
Interpretation
- Normal - the fistula becomes hyperpulsatile, and the thrill disappears.
- Inflow stenosis - the fistula remains weakly pulsatile
- Accessory vein - the fistula becomes hyperpulsatile, and the thrill persists..
Arm Elevation Test
Test For
- Outflow stenosis
How to Perform
- Elevate the arm and look for collapse of the fistula.
Interpretation
- Normal - the fistula collapses
- Outflow stenosis - the part proximal to the stenosis will collapse and the distal part will remain distended
Extra Credit
Complications of AV Fistula
- Aneurysm
- Failure to mature
- Haematoma
- Stenosis - inflow or outflow
- Thrombosis
- Steal syndrome - ischaemia distal to the fistula
- Infection
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