Ultrasound Guided Cannulation of Dialysis Fistulas

Haemodialysis patients need to have two needles inserted into a large surgically altered vein (fistula) or surgical vascular graft/shunt for every dialysis session. Some fistulas or shunts may be more difficult to insert needles into than others. As such a system of colour coding or "traffic lighting" of patients is in place in most units. A "green light" patient is easy to "needle" with two needles and the majority of staff within the unit will be able to connect the patients to the dialysis machine. A "red light" patient is reserved for the more experienced staff within the unit who will often have to be timetabled to work specific times so that they are present to connect certain patients to the dialysis machines. "Amber light" fistulas lie between these two extremes.

Ultrasound (US) is routinely used in many hospitals and many dialysis units will have access to a machine to assess patients for problems. Indeed central venous line insertions for dialysis are now almost always performed under US guidance since two large studies in this area in 2002 provided strong evidence that US guided placement significantly reduces complications during catheter placement and a reduction in the number of attempts at insertion. In addition the National Institute of Clinical Excellence in the UK provided evidence that insertion time is quicker although this association was statistically less convincing.

Ultrasound offers the advantage of dynamic imaging without the risks of radiation exposure and can be done as an office based procedure using portable equipment.

Studies in emergency departments and particularly in paediatric care have suggested that US guidance can improve the speed and accuracy of cannulation in peripheral veins for intravenous access.

We suggest that US guided cannulation of fistulas might improve the cannulation rate of more difficult fistulas and potentially reduce the time required to commence dialysis and the number of local complications of cannulation (haematoma/aneurysm/infection).

To our knowledge US is not used in cannulation guidance in any dialysis units, although most units will have access to a machine as above. We therefore propose to perform a randomised controlled trial of US guided cannulation of fistulas versus current practice (blind cannulation) to assess the effectiveness of US controlled cannulation in a busy dialysis unit.

Inclusion criteria

• Dialysis 3X per week
• Dialysing via 2 needles in fistula
• No deviation from routine dialysis protocol (additional or no heparin etc)

Exclusion criteria

a. Active or recent fistula infection/thrombosis/intervention in 6/52 of study

Withdrawal criteria:

• Patient request
• Patient non compliance with study protocol