Assessment of perfusion of the foot in patients with a diabetic foot ulcer

Transcription

1 Assessment of perfusion of the foot in patients with a diabetic foot ulcer Rob Hinchliffe St George s Vascular Institute, London IWGDF 2015 The Hague

2 Assessment of perfusion of the foot in patients with a diabetic foot ulcer Definition How? Why? Guidance / controversy

3 Critical limb ischaemia Recommendation 16 (TASC II) CLI = patients with chronic ischemic rest pain, ulcers or gangrene due to PAD. Patients with ulcers / gangrene, presence of CLI is suggested by: ankle pressure <70 mmhg toe systolic pressure <50 mmhg. No consensus on vascular hemodynamic (perfusion) parameters.

4 Definition of reduced perfusion No standard definition of perfusion or PAD Perfusion associated with PAD Other causes of reduced perfusion (oedema, infection, CV dysfunction) Dysregulated perfusion (microvascular circulation) Level of perfusion required to maintain foot integrity / heal wounds?

5 How to measure reduced perfusion Clinical examination Pressure (ankle / digit) Perfusion assessment of skin / adnexal tissues

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7 Pitfalls and limitations Clinical examination Experience / oedema / infection / calcification Pressure (ankle / digit) Experience / availability / oedema / calcification Perfusion assessment of skin / adnexal tissues Experience / availability / cost / oedema / infection / calcification

8 The pitfalls of pulse examination Individual proportions of severe misdiagnosis (pulse felt below 0.71 or no pulse felt above 0.96, shaded bars) and the best individual cutoff levels (ABI, line with triangles) Lundin et al, World J Surg 1999; 23:

9 Diagnostic utility of clinical assessment in severe PAD in diabetes Severe defined as ABI 0.5 < 1 block claudication patient reported history of PAD age absent or diminished peripheral pulses venous filling time >20 seconds J Clin Epidemiol. 1997;50:659-68

10 PAD diagnostic tests Performance of tests established in those without diabetes Performance less well charted in those with diabetes Generally worse performance in diabetes population

11 Diagnosis Likelihood ratios: meaningful comparator relating to clinical decision making PLR: probability a test is positive in a person with disease compared with probability of this result in disease free individual NLR: probability of a negative test in a disease-free individual compared with a person with the disease Likelihood ratio of 1 0 is unhelpful: the percentage of sick and well people with the test result is the same PLR 10 and a NLR 0.1 considered markers good test performance

12 Diagnosis WCC <7 X 10 9 cells per L PSA >20 μg/l Faecal occult blood test NLR 0.10 in diagnosing (excluding) appendicitis - 45% approximate change in probability PLR 6.3 in diagnosing prostate cancer + 35% approximate change in probability PLR 7.5 in detecting colorectal cancers 12

13 Diagnosis Overall measures of index text performance Index test PLR NLR ABI < (8) (0.3) TBI < <0.1 Pulse oximetry 2% drop Mono OR biphasic waveform IWGDF PAD Working Group

14 PAD as a prognostic indicator Ulceration Failure to heal an ulcer Amputation Death

15 Cardiovascular risk / mortality Framingham study: non-palpable pedal pulses stronger risk factor for CV disease than glucose intolerance, and those with both conditions at substantially greater risk than either alone PAD in the general population is a powerful predictor of overall mortality, irrespective of gender, symptoms or populations Am Heart J. 1998;136: Circ Res. 2015;116:

16 Diabetologia. 2008;51:747-55

17 PAD in validated DFU scoring systems Ince P Diabetes Care 2008;31:964-7

18 Why identify PAD / quantify reduced perfusion? CV risk factor management Diagnosis / Prognosis / Intervention planning Identify those who are at risk of amputation Information about healing potential Identify those who require revascularisation and who will not heal without revascularisation Regional perfusion assessment (angiosome revascularisation)

19 Controversies / Guidelines Does perfusion inform decision to revascularise? Does low perfusion result in poor outcome?

20 What proportion of patients with DFU and PAD are revascularisable? Consecutive series of 344 patients CLI and diabetes CLI: foot ulcer, ankle pressure <70mm Hg, toe pressure <50mm Hg 97% revascularised (86% PTA, 11% bypass) Faglia E. Int J Low Extrem Wounds. 2012;11:

21 What proportion of patients with PAD and ulceration are revascularised? Experienced European centres ABI <0.5 Vascular imaging 56% Revascularisation 43%

22 Lack of uniformity of decision making about revascularisation

23 What happens to those with severe PAD/perfusion deficit not revascularised? Elgzyri T, Eur J Vasc Endovasc Surg. 2013;46:110-7

24 Elgzyri T, Eur J Vasc Endovasc Surg. 2013;46:110-7

25 What factors are associated with ulcer healing in patients who are not revascularised? Elgzyri T, Eur J Vasc Endovasc Surg. 2013;46:110-7

26 Does assessment of perfusion aid decision making? Trust the ABPI when low not when high ABPI <0.6 (toe pressure / TcpO2 <30mm Hg) or wound healing response poor consider early revascularisation ABPI >0.6 (toe pressure >55mm Hg TcpO2 >50mm Hg) trial of 6 weeks of best wound care and assess response

27 Drain sepsis / urgent revascularisation IWGDF PAD Guidelines 2012 ESVS CLI & DF Guidelines 2011 Does assessment of perfusion aid decision making? Trust the ABPI when low not when high ABPI <0.6 (toe pressure / TcpO2 <30mm Hg) or wound healing response poor consider early revascularisation ABPI >0.6 (toe pressure >55mm Hg TcpO2 >50mm Hg) trial of 6 weeks of best wound care and assess response

28 Prognosis - healing Annualised healing rates 18-61% IWGDF PAD Working Group 2015

29 Prognosis major amputation Annualised healing rates 3-19% Index test PLR Ankle pressure <50mmHg 1.3 Ankle pressure <70mmHg 4.3 Ankle pressure <50mmHg OR ABI < Toe pressure < 30mmHg 2.6 Toe pressure < 45mmHg 2.1 Fluorescein toe slope 4.0 Mono/ absent doppler 2.2 IWGDF PAD Working Group 2015

30 Prognosis Healing / Amputation Taken in context of pre-test probability Univariable analyses Perfusion only one component Variable standards of care

31 Wound Ischaemia Foot Infection Score J Vasc Surg 2014; 59:

32 Wound Ischaemia Foot Infection Score estimated risk of amputation at 1 year

33 Wound Ischaemia Foot Infection Score estimated likelihood of benefit of /requirement for revasculrisation

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35 Conclusions No ideal bedside test reliably exclude (confirm) PAD TBI 0.75 and triphasic waveform helpful to exclude PAD PAD is present in the majority of DFU patients Consequences of missing PAD may be high - selection of NLR as outcome measure in diagnostic studies

36 Conclusions TcpO 2 25mmHg predictor healing Ankle pressure <50mmHg OR ABI <0.5 predictor of amputation All patients with PAD and DFU should be considered for revascularisation.

37 Conclusions.but not all need revascularisation Indications for revascularisation multifactorial (unclear) Evidence on outcomes of those not revascularised emerging Perfusion assessment helpful but not in isolation (WifI)