Multidisciplinary panel recommends early revascularisation of diabetic foot to save legs

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At the upcoming British Society of Interventional Radiology (12–14 November, Liverpool, UK), there is a BSIR “BSIR Meets Parliament” session chaired by Neil Carmichael MP and Chair of the All Party Parliamentary Group on Vascular Disease, with Fiona Miller giving an update on the National Vascular Registry and Simon McPherson presenting the results of the NCEPOD (National Confidential Enquiry into Patient Outcome and Death) review of lower limb amputation. 

Delays in revascularisation of diabetic foot in the UK directly relate to legs being lost to amputation. Early referral to interventionists is of critical importance and interventional radiologists must prioritise the revascularisation of diabetic foot patients to help save legs, a UK multidisciplinary panel recommended.

The panel, consisting of Michael Edmonds (a diabetologist), Cliff Shearman (a vascular surgeon), and Trevor Cleveland, Jon Moss, Iain Robertson and Raman Uberoi (all interventional radiologists), met Interventional News at a press conference at CIRSE 2014 in Glasgow, UK.

At the upcoming British Society of Interventional Radiology (12–14 November, Liverpool, UK), there is a BSIR “BSIR Meets Parliament” session chaired by Neil Carmichael MP and Chair of the All Party Parliamentary Group on Vascular Disease, with Fiona Miller giving an update on the National Vascular Registry and Simon McPherson presenting the results of the NCEPOD (National Confidential Enquiry into Patient Outcome and Death) review of lower limb amputation.

At CIRSE the panel explained: There are several factors that could help speed up the process of patients with diabetic foot getting revascularisation: A well-functioning multidisciplinary team where early referral to revascularisation is recommended; a seat at the table for interventional radiologists who need to be part of the core teams that make decisions about revascularisation for patients with diabetic feet; and a re-ordering of priority lists for interventional radiologists so that they see these cases urgently.

Michael Edmonds, King’s College Hospital, London, said: “Diabetes damages the nerves and this leads to numb feet that are sus-ceptible to the development of ulcers. These are very prone to infection by bacteria which can cause thrombosis of the arteries of the feet and gangrene. In addition, diabetes damages the arteries of the lower limb. This means that blood supply is reduced to the foot and cannot be increased to aid the healing of the ulcer and eradicate the infection, which can lead to gangrene and the need for amputation. However, if the damage to the arteries is severe, this leads to a considerable reduction of blood supply to the foot, so called critical limb ischaemia, and this of itself can lead to gangrene and amputation. So the drivers to gangrene are infection and poor blood supply in varying degrees. At one end of the spectrum, there is considerable infection of a diabetic foot ulcer and a moderate reduction in blood supply, the so-called neuroischaemic foot. At the other end, there is a massive reduction in blood supply with a little infection, and that is critical limb ischaemia.”

“There is a crucial role for interventional radiology techniques and solutions to the problem,” said Edmonds. “Angioplasty helps to revascularise the foot, whether it is temporarily to restore blood flow in order to help diabetic ulcers to heal, or longer-term as a treatment for critical limb ischaemia. It also serves as an important technique to maintain the patency of bypass grafts after patients have had a surgical intervention,” he added.

The panel highlighted that the delay that patients faced before they were offered revascularisation (whether by angioplasty or surgical bypass) was a large stumbling block in the patient care pathway that led to legs being lost to amputation. “Patients are not get-ting to interventionists in time to undergo angioplasty,” said Edmonds. “Everybody agrees that the so-called critically ischaemic foot should be revascularised so as to save the limb. Where there is controversy is when we have a diabetic patient with a foot ulcer that is not healing in a moderately ischaemic limb. This foot would not have got into trouble unless it had been subjected to minor trauma which is often unsensed because of nerve damage. However, having got into trouble, the foot cannot heal the ulcer because it cannot increase its blood supply. We believe there is a role for angioplasty to improve the blood supply to get such ulcers healed. However, all such patients do not get to the interventionalists. Healthcare professionals see an ulcer and think that it needs conservative care, and will wait and wait. Almost inevitably, the unhealed ulcer becomes infected and this can eventually destroy the foot. The dilemma is a 1cm diameter ulcer with a transcutaneous oxygen tension of 35mmHg and an ankle brachial pressure index of around 0.6. Should this be treated conservatively or by aggressive revascularisation, which we favour at Kings?” Edmonds asked.

Interventional radiologists not on the core teams

The panel also commented on the fact that interventional radiologists were not on the core teams that were making treatment deci-sions for people with diabetes.

Trevor Cleveland, Sheffield Vascular Institute, Sheffield, said: “If you look at the diabetic foot care team and British Diabetic As-sociation teams, interventional radiology is not there. If we were part of the core team, there at the sharp end, that would certainly make a difference.

 

Cliff Shearman, University of Southampton, Southampton, agreed: “Given the current practice of publication of amputation rates by provider, if you are part of the team, there will be a change to ensure that the team does not report poor outcomes. The other as-pect is to have mandated guidelines, and there is not good enough evidence for that, but if you ask patients, they would clearly rather be seen sooner rather than later, once the decision to intervene has been made.”

Cleveland then pointed to the stroke strategy as a blueprint. “There was some enthusiasm for it from the centre, and we now have to deliver Duplex within 24 hours of the patient being admitted. There has been some funding to help deliver that. This is exactly the kind of framework and environment that would help diabetic foot treatment,” he noted.

The panel also urged interventional radiologists to prioritise the revascularisation of patients with diabetic foot in order to decrease the number of amputations taking place in the UK.

Iain Robertson, Greater Glasgow and Clyde NHS, Glasgow, said: “There are a lot of competing demands in interventional radiol-ogy units and we choose to prioritise them in certain ways. I suspect that the prioritisation of diabetic foot and critical limb ischaemia is not right yet in many units. The challenge would be for interventional radiologists to think about it differently and prioritise these cases as we would, say, elective endovascular repair for instance, which sits in an aneurysm screening pathway. We need to see critical limb ischaemia as a priority.”

 

Jon Moss, Gartnavel General Hospital, Glasgow, then said: “Another solution is to increase the interventional radiology work-force. We have unfilled posts, and it is quite difficult to balance time when you have a leg to fix, a septic kidney or an abscess that needs to be drained as an emergency, and the renal physicians want a line put in so that they can dialyse a patient. We do feel under pressure and are expected to make contributions to diagnostic radiology as well. I personally think we should be free from that be-cause we are a different breed.”

What solutions can interventional radiology offer?

Moss said “It is still unclear for some patients whether an angioplasty or bypass is the best strategy. We tend to do the angioplasty because it is quicker and easier and Government-funded trials such as BASIL-2 will examine this question [The UK NIHR HTA-funded BASIL-2 randomised controlled trial will compare outcomes following vein bypass surgery and best endovascular interven-tion in patients with severe limb ischaemia due to below the knee disease]. The level of enthusiasm for this type of bypass will vary from vascular surgeon to vascular surgeon in the UK, from the enthusiastic to nihilistic. Similarly, with angioplasty down at the level of the foot, we are learning that we can push the boat our more now with balloons, wires and gadgetry, where previously we may not have been able to do anything,” he said.

Raman Uberoi, John Radcliffe Hospital, Oxford, then noted that at a practical level most centres would try an angioplasty, or more complex revascularisation first, before they get to surgery, depending on local expertise as well as other factors including the patient’s health and the availability of vein. “We have a number of innovations in the angioplasty technology with smaller profile devices, catheters and stents, which enable us to treat very distally, even use distal approaches to revascularise. We are also able to maintain that revascularisation for a longer period of time. We have not definitively demonstrated more complex interventions, such as the use of drug-eluting balloons and drug-eluting stents are worth the additional expense but it is certainly better than waiting until the patient faces an amputation that will have a huge impact on their quality of life and which is extremely expensive,” he noted.

“Diabetes affects small vessels, very often arteries below the knee, so around 3mm vesssels that are difficult to surgically bypass to and in reality probably need vein. A limitation for simple angioplasty alone was that it did not work well with that kind of complex and multi-level disease,” Cleveland explained.

“The very small gauge equipment that we now have, has made it possible to get down to the level of the foot. On top of that we have the potential to use drug-eluting stent and drug-eluting balloons. Our difficulty lies in the fact that we do not have good quality long-term data to tell us that there is a difference between a £200 balloon and a £1,000 drug-eluting stent or drug-eluting balloon. This is part of the development process. We have National Institute of Health and Care excellence (NICE) guidance that recommends that angioplasty is the first step and that a bare metal stent can be used as a bail-out option. If you look across Europe that is not the way people are being treated. It might be that NICE is right, or it may be that the European enthusiasm is right, the reality is we do not know. We have a reimbursement system that probably does not recognise the cost of the more expensive devices. On the flipside [with the more expensive devices] we may be putting a bucketload of money into people’s arteries that does not really do them a whole lot of good, and from a healthcare economy perspective is nonsense, so there is a lot of uncertainty,” Cleveland ex-plained.

Critical limb ischaemia—a term past its sell-by date

Critical limb ischaemia does not have a single, widely-accepted definition. The multidisciplinary panel agreed that the definition of critical limb ischaemia remained a “thorny issue”. “It is hard enough defining it among clinicians who revascularise. Further com-plexity is added when primary care doctors and nurses refer to this term,” said Shearman.

“There have been several attempts at definition, most of which have been unsuccessful, because in the real world most people lose their legs for a combination of reasons. I think critical limb ischaemia is a term that is past its sell-by date. You cannot ever define a limb that will be lost by hard measurable criteria alone, because of the multifactorial nature of it. In reality, critical limb ischaemia is a way of saying that a limb has such poor blood supply that there is a real risk of limb loss if nothing is done to revascularise the leg. Most clinicians are pretty good at assessing and predicting whether a limb needs revascularisation or not, so we should not shy away from the fact that it is a pragmatic judgement. Of course, one of the big difficulties with not having an objective scoring system is that if you want to report trials to evaluate treatments, there is a problem. So there are scoring systems like the Rutherford scoring system based on symptoms and signs which is quite useful for categorising patients. However, when treating patients you have to be more pragmatic.

“In some ways it might be that the term critical limb ischaemia has been a disadvantage to people with diabetes in regards to getting patients referred on to interventionists. It might be that healthcare teams may not necessarily categorise the patient as having critical limb ischaemia and then delay referral,” Shearman concluded.

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