Disclosure. Objectives. Pre Test Question One. Pre Test Question Three. Pre Test Question Two. Assessing Bloodflow and Perfusion in Chronic Wounds

Transcription

1 Disclosure Assessing Bloodflow and Perfusion in Chronic Wounds Enoch T. Huang, MD, MPH&TM, FUHM Adventist Medical Center Portland, OR Novadaq Technologies, Inc. Speaker s Bureau Consultant Clinician Advisory Board Center of Research and Education Objectives By the end of this lecture, attendees should be able to: Appreciate the importance of a vascular assessment in the lower extremity wound Differentiate what data each type of assessment provides Develop a strategy to incorporate different imaging technologies into care plan Pre Test Question One What percentage of non traumatic lower extremity amputations have had pre operative angiography? A % B % C % D % Pre Test Question Two Which disease has the highest 5 year mortality? A. Breast Cancer B. Colorectal Cancer C. Critical Limb Ischemia D. Stroke Pre Test Question Three Which imaging modality provides direct visualization of microcirculation? A. Skin Perfusion Pressure B. Fluorescence Angiography C. Transcutaneous Tissue Oximetry D. Contrast Angiography 1

2 Pre Test Question Four Which test provides the best prediction for wound healing? A. Skin Perfusion Pressure B. Fluorescence Angiography C. Transcutaneous Tissue Oximetry D. Ankle Brachial Index Pre Test Question Five What is the chance of successful post BKA ambulation with a prosthesis for a 75 yo diabetic patient who needs a BKA for a non healing foot ulcer? A. 20% B. 40% C. 60% D. 80% Pre Test Question Six The Foot as End Organ Which imaging modality has the safest contrast risk profile? A. Contrast Angiography B. CT Angiography C. Fluorescence Angiography D. Magnetic Resonance Angiography Categories of PAD Asymptomatic Intermittent Claudication Chronic Limb Ischemia chronic, severely compromised arterial blood supply in the affected extremity that manifests as rest ischemic pain, ulcers or gangrene in various combinations Acute Limb Ischemia refers to a rapid decrease of perfusion in the affected extremity that requires urgent revascularization to preserve tissue viability Symptoms Classic Claudication 10% of cases Cramp like leg muscle pain with exercise, better with rest Calf pain typical (pain may occur in thigh, buttock) Pain worse with exertion Pain relieved within 10 minutes rest Pain relieved with rest and dependent position Atypical Leg Pain 50% of cases Asymptomatic 40% of cases 2

3 Symptoms The Natural History of PAD Population > 55 years Exertional pain 70% arterial stenosis Nocturnal pain 70 to 90% arterial stenosis Ischemic rest pain >90% arterial stenosis Asymptomatic Claudicants CLI 50% 40% 10% PAD Outcomes 5 Year Outcomes CV M/M Stable Claudication 73% Worsening Claudication 16% Leg Bypass Surgery 7% Major Amputation 4% Nonfatal CV Events (MI/Stroke) 20% Mortality 20 30% Weitz, et al. Circulation 1996; 94: PAD in New Onset Type 2 DM PAD awareness is LOW 100 Ebola 5 year mortality for PAD/CLI is higher than for many cancers CLI patients have a higher risk of death than amputation a. http//seer.cancer.gov/statfacts/html/prost.html b. http//seer.cancer.gov/statfacts/html/breast.htm. c. Kaul P Circulationion 2004;110: d. Weitz JL Circulation 1996;94: e. http//seer.cancer.gov/statfacts/html/colorect.html f. Hartman A Neurology 2001;57: g. Eur J Vasc Surg 1996; 11: Ouriel Lancet 2001;358:

4 The path to amputation 5 year mortality It s just an ulcer Costs to treat a DFU over a 2 year period after detection Amputation is Expensive $50,000 $45,000 $40,000 $40,786 $45,301 Major lower limb amputation a $40,000 45,000 first year Rehab doubles cost $35,000 $30,000 $25,000 $20,000 $27,987 $33,046 Cost (US$) CMS Medicare 1996 b N=3565 patients underwent amputation, 1 year: 26% required subsequent amputation 33% died $15,000 Acute and post acute costs: > $4.3 billion annually $10,000 Minnesota c $5,000 Median charge per amputation $32,219 $ Cumulative Inpatient hospitalization charges $56.5 million Ramsey, et al Diabetes Care. 1999; 22:382 Cost analyses based on percent change in the medical component of the US consumer price index a. Norgren L J Vasc Surg; 45: b. Dillingham TR Arch Phys Med Rehab 2005; 86: c. Peacock JM Prev Chron Dis 2011; 8: A141-A148 A148 Amputation affects Quality of Life Early Fate of BKA Patients Peri operative Death Above Knee Amputation Secondary Healing Primary Healing TASC II J Vasc Surg. 2007;45 (Suppl S) 4

5 Two Year Fate of BKA Patients Survival After Amputation Dead Above Knee Amputation Contralateral Amputation Full Mobility TASC II J Vasc Surg. 2007;45 (Suppl S) Subramaniam B Asesth Analg 2005; 100: Amputation vs. Cancer Physiologic Cost of Amputation Unadvertised Impact of Amputation for PAD TASC II: Critical Limb Ischemia >200,000 per year First recommendation for most CLI patients (<25% have pre op angiography) 30 day peri operative mortality BKA 5 8% AKA 8 12% 24 month overall mortality 40% > 5 yrs Survivors fitted for an ambulating with a prosthesis BKA 50% (<20% if >65 yo) AKA 25% Norgren L J Vasc Surg 2007; 45:

6 Underuse of Revascularization and Angiography one year prior to Major Amputation Intensity of Pre Amputation Evaluation Goodney PP Circ Qual Outcomes 2012; 5: Goodney PP Circ Qual Outcomes 2012; 5: Revascularization Reduces Amputation Making the Diagnosis Balar NN Endovascular Today 2011: Signs Dry, scaly, shiny atrophic skin Skin hairless over lower extremity (e.g. shin) Dystrophic, brittle toenails Non healing ulcers or other lower extremity wounds Decreased skin temperature (cool feet) Decreased Capillary Refill Time Signs Distal extremity color change with position Skin rubor when leg dependent Skin pallor when leg elevated >1 minute Color returns within 15 seconds in mild cases Delay >40 seconds suggests severe ischemia 6

7 Physical Examination Pulse Checks Femoral Popliteal l Posterior Tibial Dorsalis Pedis Presence of a pulse does not equal normal vasculature 7

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9 Physical Examination Postural Changes Raise both legs to about 60 until maximal pallor of feet develops Have patient sit up with legs dangling down Compare both feet, noting: Return of pinkness to the skin (<10 sec) Filling of the veins of the feet and ankles (~15 sec) Look for rubor to replace the pallor of the dependent foot Assessment of PAD Palpation of Pulses CT Angiography (CTA) Handheld Doppler Magnetic Resonance Angiography Ankle Brachial Index (ABI) (MRA) Toe Brachial Index (TBI) Traditional Angiography Segmental Pressures with Intravascular Ultrasound (IVUS) Plethysmography Fluorescence Angiography (ICGA) Arterial Duplex Ultrasonography Skin Perfusion Pressures (SPP) Pulse Volume Recordings (PVR) Transcutaneous Oxygen Measurement (TCOM) Ankle Brachial Index (ABI) Calculated by dividing the ankle pressure over the highest brachial pressure <0.9 is abnormal and indicates PAD 0.7 and 0.9 is considered mild disease 0.5 and 0.69 is moderate disease < 0.5 is severe disease Can be falsely elevated in diabetics with medial artery calcification (non compressible arteries) Handheld Doppler Triphasic (three clear sounds at each pulse beat): a triphasic sound indicates a very healthy artery, with no impedance to blood flow, and good elastic arterial walls. Biphasic (two clear sounds at each pulse beat): a biphasic pulse sound indicates reasonable arterial health Monophasic (one sound at each pulse beat): a monophasic pulse sound indicates poor arterial health, inelastic arteries and poor peripheral perfusion Arterial Waveforms Arterial Duplex Ultrasonography 9

10 Skin Perfusion Pressure Angiosomes Mapping of angiosomes may help identify areas of pathology Focused intervention is more effective for wound healing Pulse Volume Recordings Pre operative measurement of external pressure required to stop isotope washout of iodine in 60 patients undergoing BKA SPP <20 mmhg had 75% failure rate (6 of 8) SPP >20 and <30 had 33% failure rate (4 of 12) SPP >30 had 10% failure rate (4 of 40) Holstein P, et al. Acta Orthop Scand, 50: (1979) Predicting Wound Healing 39 major amputations (15 AKA, 24 BKA) 23 minor amputations (4 TMA, 19 toes) Adera HM, et al, J Vasc Surg, 21: (1995) SPP of 30 mmhg used as cutoff PPV = predicting wound failure 100% for major amputation, 67% for minor amputation NPV = predicting wound healing 83% for major amputation, 75% for minor amputation Adera HM, et al, J Vasc Surg, 21: (1995) 10

11 TCOM Wound Oxygenation Transcutaneous oximetry TCOM, PtcO 2, TcpO 2 Measurement in mmhg Predicting Healing Thirty eight studies since 1982 suggest that hypoxia sufficient to impair or prevent wound healing is defined as TcPO 2 < 40 mmhg. Sea level air TcPO 2 values can be used to predict which wounds will not heal spontaneously Because hypoxia predictably leads to wound healing impairment or failure, it is easier to determine a value below which a wound will not heal than to find a value above which a wound is reliably predicted to heal Fife C, et al. Chapter X. Transcutaneous Oximetry In Press Amputation Healing A sea level air TcPO 2 < 40 mmhg is associated with a lower than normal likelihood of amputation healing If the baseline TcPO 2 increases < 10 mmhg while breathing 100% sea level oxygen (oxygen challenge), this is at least 68% accurate in predicting failure of healing after an amputation in patients in whom no attempt is made nor is possible to increase wound oxygenation (e.g., revascularization or HBOT) Fife C, et al. Chapter X. Transcutaneous Oximetry In Press Predicting Response to Revascularization An absolute increase in TcPO 2 of > 30 mmhg after revascularization (by surgery or endovascular procedure) is a significant ifi improvement, and is usually associated with subsequent wound healing. TcPO 2 values can continue to increase for as long as 28 days after revascularization. Fife C, et al. Chapter X. Transcutaneous Oximetry In Press Predicting Benefit from HBO 2 Sea level air TcPO 2 values alone cannot be used to predict benefit of subsequent HBOT because even patients with very low sea level air values (e.g. 5 mm Hg) have subsequently healed with HBOT In diabetic foot ulcers, measuring TcPO 2 values in the hyperbaric chamber are the most reliable way to predict benefit from HBOT. A TcPO 2 > 200 mmhg during hyperbaric oxygen therapy is a predictor of success for HBOT in benefitting a diabetic foot ulcer. This test is 75% reliable. Conversely, in chamber TcPO 2 values < 100 mmhg are closely associated with failure of HBOT in diabetic foot ulcers (reliability 89%) Fife C, et al. Chapter X. Transcutaneous Oximetry In Press 11

12 SPP vs. TCOM CT Angiogram / MRA Prospective comparative study of 100 patients SPP alone successfully predicted wound outcome in 87% of the cohort compared to TcPO 2 at a rate of 64% (P < ) SPP was more sensitive in its ability to predict wound healing relative to TcPO 2 (90% versus 66%; P <0.0001) SPP with values 30 mmhg is a useful positive independent predictor of wound healing potential Lo T, et al. Wounds 2009, 21(11): Angiography Intravascular Ultrasound Fluorescence Angiography Fluorescence Angiography: from skeptic to apologist a pol o gist /ə päləjəst/ noun a person who defends or supports something (such as a religion, cause, or organization) that is being criticized or attacked by other people Synonyms: defender, supporter, upholder, advocate, proponent, exponent, propagandist, champion, campaigner Merriam Webster Dictionary 12

13 Fluorescence Angiography Indocyanin Green (ICG) is a fluorescent dye that is injected via a peripheral IV ICG binds to plasma proteins and is confined to the intravascular space Hepatically metabolized with half life of 3 4 minutes Only contraindication is Iodine allergy Fluorescence Angiography Near IR laser light is shined on the area of interest ICG fluoresces and is picked up by the camera Quantitative analysis can be done using calculations of Ingress and Egress of ICG Fluorescence Angiography The only existing technology that allows Ingress Egress Rate = Egress time direct visualization of the microvascular circulation Ingress Ingress Rate = time Egress Better than what the eye can see Imaging Techniques Static imaging camera is not moved during the entire study Allows quantitative analysis Allows comparisons between studies Dynamic imaging camera is moved over the body Allows viewing of multiple areas Misses the ingress/egress phase of the study Does not allow for quantitative analysis or comparisons 100,000 foot view ICG binds to the blood, and if there is blood flow, there will be ICG and the image will glow Assumption if there is good blood flow, there will be a glow on the screen more glow equals more flow (ingress rate can be used to measure PAD) 13

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15 Standardize Dosing of ICG Should a standard dose be used for all patients regardless of their size? If dose is changed between images, it is difficult to make comparisons cc ICG cc ICG Operational issues with regard to number of doses per vial of ICG 100,000 foot view Problems Dose of ICG dye affects image Physiologic state of the limb affects image Temperature Infection/Inflammation Wound/No wound Skin color may affect intensity of image We don t have a good grasp yet on what the numbers tell us in a predictive manner 15

16 Does ICGA correlate with ABI? 46 patients underwent 57 revascularization procedures (44 Endo, 11 Open and 2 Hybrid) for 48 lower limb wounds An ingress of 27.3 PxS and ingress rate of 1.1 PxS/sec corresponded d to an ABI of 0.4 Post revascularization, 80% of patients had ingress 27.3 PxS, 85% had ingress rates 1.1 PxS/sec, and 100% of those with compressible ABIs had an ABI 0.4 Jonathan D. Braun, Pooja Rajguru, David G. Armstrong, Joseph L. Mills Objective Indocyanine Green Angiographic Criteria Using Ingress and Ingress Rate to detect SVS Lower Extremity Threatened Limb Classification (WIfI) Grade 3 Ischemia (In Press) Ingress Ingress Rate Egress N/A N/A N/A Egress Rate N/A N/A N/A Curve Integral Ingress Ingress Rate Egress 6 1 Egress Rate Curve Integral Data free zone Existing studies correlate ICGA metrics to existing iti standards d No studies give any prediction as to whether a wound is going to heal 100,000 foot view Images of obvious areas of focal ischemia are very powerful for patient and clinician Insufficient i explanation of what the images can or cannot tell the clinician Difficult to make an informed clinical decision for some images 16

17 3 mm view Normal Wound Healing Source: Dr. W Li The Angiogenesis Foundation ANGIOGENESIS ON VESSEL NORMALIZATION A new model for angiogenesis Deeper understanding di of physiology of wound healing Incorporating ICGA into clinical practice BASELINE VASCULARITY ACUTE INJURY MAXIMAL ANGIOGENESIS BASELINE VASCULARITY HEALED Chronic Wound Healing Source: Dr. W Li The Angiogenesis Foundation ANGIOGENESIS ON PERSISTS ABNORMALLY STUCK Hyperfluorescence Model of Angiogenesis, Hyperpermeability, and Resolution Evans Blue Dye Injection CHRONIC INFLAMMATION BASELINE VASCULARITY PERIMETER ANGIOGENESIS NOT HEALED Ad-VEGF-A 164 ACUTE INJURY Tx Wound Microcirculation Monitoring Source: Dr. W Li The Angiogenesis Foundation High Glow with Low Flow? Hyperfluorescence Return to normal vascularity Patients with severe PAD may have images that t show enhancement of the foot Patients are expecting little to no enhancement, but images still light up ANGIOGENESIS INCREASES IN HEALING, THEN IS PRUNED TO PHYSIOLOGICAL BASELINE 17

18 Hyperfluorescence Explains the contradiction that one sees with a bright blush in a limb with known PAD Decrease in hyperfluorescence may correlate with decrease inflammation and improved tissue function Incorporation of ICGA into Clinical Practice What can ICGA show us? Microvascular perfusion Response to intervention Focal Hypoperfusion/Ischemia Chronic inflammation? Angiogenesis? 18

19 Does ICGA show angiogenesis? Tx Wound Microcirculation Monitoring Source: Dr. W Li The Angiogenesis Foundation A superficial 110 understanding would 100 predict that as tissue angiogenesis increases, luminescence increases tcpo2 60 Vascular Density of Irradiated Tissue Treated With HBO LSICS wound yr 3 yrs Hyperbaric Oxygen Session - Time Marx, RE, Hyperbaric oxygen in oral and maxillofacial surgery, Problem wounds and hyperbaric oxygen, 1991 Hyperfluorescence Return to normal vascularity ANGIOGENESIS INCREASES IN HEALING, THEN IS PRUNED TO PHYSIOLOGICAL BASELINE Enhancing Patient Selection ICGA in Surgical Practice Incorporation of ICGA into surgical practice Incorporation into lower extremity assessment Serial evaluations to determine clinical response to therapy ICGA guided d debridement of wounds ICGA guided surgical planning Where does a single measurement fall on the angiogenesis bell curve? Case Presentation: IB 19

20 1/13/15 MRI of the lower leg Superficial edema without evidence of abscess or sinus tract Marrow signal is normal No evidence of osteomyelitis Severe posterior compartment atrophy Case discussed with radiologist No evidence of any soft tissue necrosis of the anterior tibial muscle compartment One week later 2/11/15 Patient taken to the OR Call from surgeon: The ICGA was right! Extensive myonecrosis of the anterior tibial muscle compartment STSG applied because it had already been harvested 20

21 Back to the OR Patient referred back to surgeon with ih request that we do intra operative ICGA Surgeon says I m impressed. I wasn t sure what I was signing i up for I thought h I was just being polite and showing professional courtesy, but this really made a difference 21

22 Potential Cost Savings ICGA and Hyperbaric Medicine Avoidance of unsuccessful STSG One trip to OR versus 3 trips to OR Months of Home Health/NPWT/Wound Clinic visits The use of HBO in wound care has been increasing year after year ICGA has the potential to better inform the hyperbaric physician as to the progress of the patient 1400 Growth of the Field US HBO 2 centers Cost of Wound Care Bioskin Bioskin IND Courtesy of Tom Workman HBO2 NPWT Dressing Physician Home Health HBO2 NPWT Dressing Physician Home Health Fife, CE, Carter MJ, Walker D, Thomson B. Wound Care Outcomes and Associated Cost Among Patients Treated in U.S. Outpatient Wound Centers: Data from the U.S. Wound Registry, Wounds 2012; 24(1) Slide courtesy of Caroline Fife, MD Patient Identification Patient Selection Hyperbaric patients should have: Tissue hypoperfusion Tissue hypoxia Patients who will heal without HBO 2 Patients who might heal with HBO 2 Patients who won t heal even with HBO 2 Response to therapy 22

23 Patient Selection Hyperbaric Patient Monitoring Has there been a response to therapy? Is there angiogenesis? g Patients who will heal without Patients who might heal with Patients who won t heal even Is there improved perfusion? HBO 2 HBO 2 with HBO 2 Is there improved oxygenation? Is there a continued need for HBO 2? When do you stop HBO 2? When the body is able to carry on the process of healing Able to maintain tissue oxygenation Case Presentation: DA Able to maintain angiogenesis Able to maintain tissue regeneration 23

24 Hospital Course Intra operative s/p disarticulation of great toe Patient admitted for IV antibiotics Foot and Ankle surgery took patient for amputation of the great toe We requested that the ICGA be used intraoperatively Intra operative s/p closure of skin flaps Assessment and Plan Compromised Flap ICGA identified area of focal ischemia Surgical wound was compromised and had higher risk of healing failure Hyperbaric oxygen therapy ordered Room air TCOM on 1 st webspace was 20 mmhg rising to over 600 mmhg at 2.4 ATA Post operative Day 3 Post operative Day #28 Post HBO 2 #16 24

25 When do you stop HBO 2? Tx Wound Microcirculation Monitoring Source: Dr. W Li The Angiogenesis Foundation What are the parameters to determine when native tissue is competent? Complete healing? TCOM normalization? Hyperfluorescence Arbitrary number of treatments? Treat to normal vascularity ANGIOGENESIS INCREASES IN HEALING, THEN IS PRUNED TO PHYSIOLOGICAL BASELINE Post operative Day #35 Post HBO 2 #19 Intra operative s/p closure of skin flaps Post operative Day 3 Post operative Day #28 Post HBO 2 #16 Post operative Day #35 Post HBO 2 #19 What did ICGA answer? Was there an area of focal ischemia? YES Was there a clinical response to HBO 2? YES Case Presentation: RS Was there a need for further HBO 2? NO 25

26 History 69 year old gentleman poorly controlled diabetes atherosclerosis of the extremities previous left transmetarsal amputation because of osteomyelitis of the foot seen in our clinic in March 2013 and received a course of 50 hyperbaric oxygen treatments to save the left foot TMA that had dehisced Clinic Course Clinic Course Podiatrist called and saw patient that afternoon for x rays and labs CT Angiogram ordered as patient had pacemaker No CTO but rather multiple areas of focal narrowing of the SFA, popliteal and peroneal branches 3 vessel runoff visualized to bilateral feet Patient sent to his interventional cardiologist for evaluation Plan was for angiography and percutaneous revascularization on 12/2/14 Post Angioplasty Rotational atherectomy performed 12/2/14 Peroneal artery was patent Posterior tibial artery was opened Anterior tibial artery was occluded, but revascularization was not attempted Note was made that if the wound did not heal that a retrograde approach through the dorsalis pedal artery could be attempted 26

27 Assessment and Plan Acute Ischemia of a Wagner 4 DFU Surgical Intervention Revascularization Adjunctive HBO 2 as temporizing measure to keep tissue viable while surgery and revascularization was planned Clinic Course TCOM was 0 mmhg at the dorsal foot at sea level room air TCOM in chamber was 800 mmhg ICGA used to see what the perfusion looked like 27

28 Clinic Course What did ICGA answer? Limb salvage (TMA) vs. BKA Question as to whether patient would heal a TMA Plantar arch patent Dorsal arch ischemic Progressive necrosis of toes Podiatrist requested 2 nd angioplasty with attempt to open the anterior tibial artery prior to attempting any surgery 3 hour procedure with canalization of the dorsal arch, but unable to cross occlusion Given lack of new blood flow, prediction of 20% chance of success Was there an area of focal ischemia? YES Was there a clinical response to HBO 2? NO Was there a need for further HBO 2? MAYBE Potential Cost Savings Intra operative ICGA may have resulted in one surgery, not two Post angioplasty ICGA may have caused more Case Presentation: AW aggressive approach in the angio suite More efficient delivery of healthcare History 61 year old female with history of poorly controlled diabetes, tobacco use, and a blister on the right 4 th toe After a week, the 4 th toe looked dusky and the patient was admitted from the ER for IV antibiotics and amputation of the toe Also with necrotic area on the 5 th MT head We asked to perform ICGA in the OR 28

29 Post Op Day #19 HBOT #11 29

30 Post Op Day #28 HBOT #16 Changes in management Intraoperative ICGA allowed more definitive surgery to be done Follow up ICGA allowed demonstration of clinical efficacy of treatment Case Presentation: WD History 82 yo male with history of DM, CHF, HTN, and a scab on the left great toe for the last year Patient picked the scab off 2 weeks ago, and now presents with ih increased redness and swelling of the toe He was admitted from the ER with foul smelling drainage from the toe Physical Examination Non palpable pulses in the foot Vascular studies showed: Moderate diffuse burden and superficial femoral arterial stenotic disease Severe stenoses at the distal popliteal arteries bilaterally Severe bilateral triple vessel runoff disease 30

31 Consultations Interventional Cardiology was called for revascularization INR was elevated (on Coumadin), as was Creatinine Family needed to decide whether he would be willing to undergo dialysis Foot and Ankle surgery was called for toe amputation Surgery deferred until after revascularization Vascular Intervention Angiography showed subtotal stenosis of the distal SFA with occlusion of the peroneal and posterior tibial arteries There was successful recannulization with percutaneous transluminal rotational atherectomy, balloon, and stent implantation Toe Surgery Great toe amputated and distal metatarsal had to be removed because of gangrene, fat necrosis, and devitalized tissue underneath metatarsal head Minimal bleeding of the skin edges Hyperbaric Oxygen Therapy HBO Tx #3, Post Op Day 4 Immediate inpatient i HBO 2 started for limb salvage and compromised skin flaps 31

32 HBO Tx #5, Post Op Day 6 Treatment Plan Continue HBO 2 to preserve as much tissue as possible Follow with weekly fluorescence angiography to determine when perfusion is back to normal Integrating ICGA into Wound / Hyperbaric Medicine Identify and document patients who have hypoperfusion or focal ischemia Monitor changes in perfusion Determine stopping point ICGA guided debridement of wounds Intra operative risk stratification Caveats Lack of ICG uptake is not necessarily a marker of ischemia or hypoperfusion Single measurement less useful than serial measurements Data free zone Future Directions Systematic evaluation of the technology in multiple areas Standardization of testing and interpretation Collaborative interpretation of results amongst early adopters Research Needed RCT for intra operative ICGA for operative planning Change of surgical plan (earlier amputation, later amputation) Differences in Healing Rates Return to OR Post operative Costs 32

33 Objectives By the end of this lecture, attendees should be able to: Appreciate the importance of a vascular assessment in the lower extremity wound Differentiate what data each type of assessment provides Develop a strategy to incorporate different imaging technologies into care plan Post Test Question One What percentage of non traumatic lower extremity amputations have had pre operative angiography? A % B % C % D % Post Test Question Two Which disease has the highest 5 year mortality? A. Breast Cancer B. Colorectal Cancer C. Critical Limb Ischemia D. Stroke Post Test Question Three Which imaging modality provides direct visualization of microcirculation? A. Skin Perfusion Pressure B. Fluorescence Angiography C. Transcutaneous Tissue Oximetry D. Contrast Angiography Post Test Question Four Which test provides the best prediction for wound healing? A. Skin Perfusion Pressure B. Fluorescence Angiography C. Transcutaneous Tissue Oximetry D. Ankle Brachial Index Post Test Question Five What is the chance of successful post BKA ambulation with a prosthesis for a 75 yo diabetic patient who needs a BKA for a non healing foot ulcer? A. 20% B. 40% C. 60% D. 80% 33

34 Post Test Question Six Which imaging modality has the safest contrast risk profile? A. Contrast Angiography B. CT Angiography Questions? C. Fluorescence Angiography D. Magnetic Resonance Angiography 34