tUS for the detection of complications of AV fistulae
Research type
Research Study
Full title
Tomographic ultrasound for the detection of complications following surgically created arterio-venous fistulae for haemodialysis
IRAS ID
231979
Contact name
Steven Rogers
Contact email
Sponsor organisation
University of Manchester
Duration of Study in the UK
1 years, 4 months, 0 days
Research summary
Summary of Research
Chronic kidney disease (CKD) is a common, serious condition which affects an estimated 8.5% of the population, costing the NHS over £1.44 billion. As the disease progresses patients may eventually require renal replacement therapy (RRT) which is essentially to prevent the patient from becoming critically ill. Dialysis is the foremost method for RRT and a type of this, called 'haemodialysis' (HD), requires the formation of a arterio-venous fistula (AVF) - a surgically created communication between the patients artery and vein, usually in the arm. This creates an artificial high flow volume which is easily accessible for HD. However AVFs are vulnerable to damage due to the large volumes of blood travelling through them. In time, this can lead to narrowing of the AVF and eventually complete blockage, deeming it useless. The patient then needs to have another AVF created, if there is another suitable site, which leads to significant and potentially dangerous delays to their treatment. Surveillance of AVFs aims to recognise and treat the narrowing before it becomes a problem. This can be identified initially through a combination of physical examination and ultrasound. The gold standard however is through a 'fistulogram' which requires a needle puncture and the use of contrast and radiation, all of which can cause complications. As such ultrasound is used to detect the complication and the fistulagram is used as a confirmatory check which proceeds to angioplasty to resolve the problem. Tomographic Ultrasound (tUS) is fast and allows the surgeon to visualise the disease in 3D. tUS is a freehand, high resolution 3D ultrasound system which may reduce costs, radiation and contrast dosage and diagnostic angiogram waiting lists. This study aims to prove that tUS is accurate compared to clinical fistulagram results.
Summary of results
A well-functioning arteriovenous fistula (AVF) is essential for haemodialysis. Despite regular duplex ultrasound (DUS) a significant number of AVFs fail. Tomographic 3D ultrasound (tUS) creates a 3D image of the AVF that can be interpreted by the clinician. DUS, tUS, and fistulograms (a type of X-ray) were compared for the identification and measurement of flow limiting stenosis (a narrowing that restricts blood flow. Patients with AVF dysfunction on routine Transonic surveillance, defined as (1) > 15% reduction in flow on two consecutive occasions, (2) > 30% reduction in flow on one occasion, (3) flow of < 600 mL/sec, (4) presence of recirculation, underwent DUS. AVF tUS imaging was performed prior to fistulography. All fistulograms were reported by the same consultant radiologist and tUS images by the same vascular scientist blinded to the fistulogram results. Maximum diameter reduction (how narrow the blockage is) in all stenoses were measured using all three imaging techniques. Results: In 97 patients with 101 stenoses, the mean (standard deviation [SD]) severity of stenosis (maximum narrowing calculated as a percentage) was 63.0 _13.9%, 65.0 _ 11.6%, and 64.8 _ 11.7% for the fistulograms, DUS, and tUS respectively. The mean (_ SD) time between ultrasound and fistulography imaging was 15.0 _ 14.5 days. Assuming the fistulogram as the “gold standard”, Bland-Altman agreement for DUS was -1.9 _ 15.5% (limit of agreement [LOA] -32.2 - 28.4) compared with -1.7 _ 15.4% (LOA -31.9 - 28.4) for tUS. Median (_ interquartile range) time to complete the investigation was 09:00 _ 03:19 minutes for DUS and 03:13 _ 01:56 minutes for tUS (p < .001). In conclusion, DUS and tUS were equally accurate at detecting AVF complications but tUS investigation requires less skill and was significantly quicker than DUS.
REC name
London - Central Research Ethics Committee
REC reference
18/LO/0100
Date of REC Opinion
9 Jan 2018
REC opinion
Further Information Favourable Opinion