Insights On Testing And Treatment Of Ischemic Wounds

Author(s): 
Clinical Editor: Lawrence Karlock, DPM

Ischemic wounds can be challenging for any physician. With this in mind, the panelists discuss key indicators to look for in the history and physical exam, the effectiveness of noninvasive vascular testing and parameters for performing an amputation after bypass surgery. They also explore the treatment possibilities of angioplasty/stenting and the long leg distal bypass. Without further delay, here is what they had to say. Q: What is your workup/treatment plan when a new patient presents with an ischemic foot wound? A: Mark Beylin, DPM, says it starts by determining the patient’s chief complaints. He asks the patient for a full and clear chronological account of his or her symptoms, including initial onset, duration, attempted treatment (if any) and if there’s any history of previous episodes, etc. Richard Stillman, MD, determines if the patient has any symptoms, such as intermittent claudication or leg pain at rest, that are suggestive of arterial insufficiency. Not only is the medical history important, but Dr. Beylin notes the patient’s social history, in regard to smoking, alcohol and drug use, can reveal a direct relationship to developing an ischemic disease. He also says the patient’s family history may reveal the risk of developing certain diseases. When performing the physical examination, Dr. Stillman checks the extremity for the absence of femoral, popliteal, dorsalis pedis or posterior tibial pulses. However, he cautions that approximately 10 percent of the normal population lacks a dorsalis pedis pulse. Dr. Stillman also encourages physicians to listen for bruits, especially overlying the iliofemoral segment. When palpating the pulses, Dr. Beylin says you should also note the presence or absence of aneurysmal dilation. Dr. Stillman emphasizes recording the status of venous and capillary refilling, and noting the existence of skin atrophy, the presence of cyanosis or dependent rubor and the absence of hair growth on the toes. If you suspect arterial insufficiency, Dr. Beylin recommends checking the amount of pallor on the lower extremities upon elevation. He also checks for asymmetry, edema, stasis pigmentation, inflammatory changes, and dilated veins as well as the condition of the patient’s skin and nails. Often these patients will require a more extensive workup and Dr. Beylin says he refers them to a vascular or endovascular specialist. If the wound appears to be infected, Dr. Beylin will obtain a culture, begin preliminary antibiotics and seek an infectious diseases consult. Q: What role does noninvasive vascular testing play in the management of these wounds? What absolute toe pressure numbers do you consider adequate for healing? A: Dr. Beylin calls noninvasive vascular testing a “very useful tool” in determining a general idea of a vascular compromise. Specifically, he uses testing such as arterial/venous duplex scanning, limb blood pressures, velocity patterns and transcutaneous toe pressures. In his opinion, Dr. Beylin believes transcutaneous toe pressures greater than 40 mm are adequate for healing in most patients. Lawrence Karlock, DPM, has found that an absolute toe pressure of greater than 55 mmHg with a biphasic pedal pulse is usually satisfactory for healing while a toe pressure less than 30 mmHg is not conducive for healing. Dr. Karlock says he employs noninvasive vascular testing to obtain absolute toe pressures for patients who have any signs of a non-healing, ischemic ulcer. He prefers to use an accredited vascular lab. He says doing so gives him an objective measure of the patient’s healing potential even in the face of calcified lower extremity vessels. Other tests can be misleading according to Dr. Stillman. He says this is particularly the case when trying to use ankle-brachial pressure indices to assess patients with diabetes. Dr. Stillman points out these patients may have poorly compressible calcified arteries that tend to give normal or high pressures despite poor flow. While ultrasonic visualization of arterial anatomy does help identify aneurysmal disease or ulcerated plaque, Dr. Stillman says it generally correlates poorly with hemodynamic data. When one employs noninvasive arterial blood flow testing (such as pulse volume recording and plethysmography), pneumatic cuffs encircle the thighs, calves, ankles, feet and, sometimes, individual toes, according to Dr. Stillman. He says a transducer measures the subtle pressure changes that occur with each pulse wave and a computer chip translates the information into easily readable tracings. “This printout provides useful information about the hemodynamic significance of atherosclerotic disease,” emphasizes Dr. Stillman. “Extremely blunted distal tracings suggest likely wound healing problems unless revascularization can be accomplished.” Q: How has the role of the “long leg distal bypass” changed your prognosis of these wounds? A: In situ bypass is a sophisticated technique for arterializing the greater saphenous vein, notes Dr. Stillman. He says the vein remains in its anatomical position but is anastomosed proximally to the common femoral artery and distally to a runoff vessel such as the posterior tibial, anterior tibial or peroneal artery. Since leg veins have valves to prevent flow in the caudad direction, Dr. Stillman notes the vascular surgeon would destroy the valves with a valvulotome and then ligate the vein branches in order to avoid arteriovenous fistulas. While he calls it “an arduous and technically challenging operation,” Dr. Stillman says a successful in situ bypass has a respectable long-term patency rate and a well-deserved reputation for limb salvage, often despite extensive arterial disease. Q: What role does angioplasty/ stenting play in the infrapopliteal occlusive lesion in the diabetic foot? A: Dr. Stillman says short segment stenotic and occlusive disease responds well to endovascular managememt such as angioplasty or stenting. Stenting is particularly effective in larger vessels such as the iliac arteries, notes Dr. Stillman. He adds that the infrainguinal segment and particularly the infrapopliteal segment carry a higher restenosis rate after endovascular reconstruction. As the technology advances, Dr. Stillman says one can look for improving patency rates. He also emphasizes that even a short-term boost in arterial flow can be “a limb- and life-saver for a surgically high-risk patient with a non-healing, ischemic foot wound.” Q: What is your approach in managing ischemic wounds? A: Dr. Karlock says you should avoid aggressive debridement in a potentially ischemic wound. “This just adds insult to injury,” notes Dr. Karlock. When it comes to noninfected, stable ischemic wounds, he suggests keeping them dry until appropriate revascularization techniques are carried out. Dr. Karlock says he would avoid using any enzymatic debriding agents in this situation. Dr. Beylin notes that he does employ enzymatic-type agents such as Panafil and Accuzyme on necrotic wounds. Q: What are your thoughts on the timing of a foot amputation after bypass surgery? A: Amputation for infected gangrene should precede bypass surgery by about 10 days, notes Dr. Stillman, who adds that doing so allows the clearing of bacterial seeding from the lymphatic channels that one would encounter during the bypass. On the other hand, he says one may treat dry gangrenous toes or clean, non-healing ulcers before or after vascular reconstruction. Within five to seven days, it becomes more or less clear whether a vascular bypass has been successful, according to Dr. Beylin. Dr. Stillman says waiting until the bypass has been accomplished facilitates a more accurate assessment of local perfusion and the amputation level. Occasionally, he notes vascular surgeons will excise a clean foot ulcer or amputate a dry gangrenous toe concurrently with the bypass, but they would always use an isolated operative field and separate instruments to do so. Dr. Beylin is a staff physician at the Northwest Medical Center in Margate, Fla., and is an attending physician at the hospital’s Wound Healing Center. He is board-qualified in foot and reconstructive rearfoot and ankle surgery by the American Board of Podiatric Surgery. Dr. Stillman is the Medical Director of the Wound Healing Center and a member of the Board of Trustees of the Northwest Medical Center in Margate, Fla. He has published over 100 research papers and textbook chapters, and has authored or edited a half-dozen surgical textbooks. Dr. Karlock (pictured) is a Fellow of the American College of Foot and Ankle Surgeons and practices in Austintown, Ohio. He is a member of the Editorial Advisory Board for WOUNDS, a Compendium of Clinical Research and Practice.

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