Treating High Risk Patients Who Need Revascularization
- Updated on: 2019-10-15
- Read original article here
Emphasizing the need for multidisciplinary collaboration between podiatrists and vascular surgeons, panelists at the Western Foot and Ankle Conference discussed essential keys to assessing and treating patients with critical limb ischemia (CLI), and the utility of compression therapy in patients with venous leg edema and concomitant peripheral arterial disease (PAD).
Emphasizing that “foot care prolongs legs,” David G. Armstrong, DPM, MD, PhD, notes that patients with diabetes-related lower extremity complications who visited a podiatrist and one other diabetes team member in the past year have a profound reduction in the risk of amputation.1 What if foot care is removed from the equation? Dr. Armstrong says a study by Skrepnek and colleagues revealed that patients with diabetic foot ulcers who only went to the emergency department or hospital, in an attempt to cut costs, experienced a 50 percent increase in amputation, sepsis and death.2
Outlining the “Toe and Flow” model of the multidisciplinary team, Dr. Armstrong notes the benefits of having vascular and podiatry on the same service. He discusses the development of a “hot foot line” or a phone number within the hospital system so an on-call doctor can triage the patient in question and determine if “toe” (podiatry) or “flow” (vascular) is the primary need.
What The Literature Reveals About Compression For Patients With Venous Leg Edema And PAD
Can one safely apply compression for patients with venous leg edema and concomitant peripheral arterial disease (PAD)? Jonathan Labovitz, DPM, FACFAS, CHCQM, feels that clinicians should institute compression as a portion of patients with lower extremity edema likely suffer from a combination of arterial and venous disease.
Bandage compression pressure must exceed intravenous pressure in order for it to be most effective for venous disease, according to Nicolaides and colleagues.3 The study authors indicate that this pressure varies significantly between supine, sitting and standing positions. Initial compressive narrowing of the vein occurs between 30 to 40 mmHg in the sitting or standing positions.3 However, even light pressures can have some benefit toward venous compression, notes Dr. Labovitz.
One study analyzing the relationship between venous leg ulcer (VLU) and ambulatory venous pressure found that a venous pressure of less than 30 mmHg is associated with a zero percent incidence of VLUs, according to Dr. Labovitz, a Professor in the College of Podiatric Medicine at the Western University of Health Sciences.4 As venous pressure increases to just 31 to 40 mmHg, Dr. Labovitz says the incidence of VLU increases to 14 percent. Finally, when venous pressure exceeds 90 mmHg, the study authors noted this is associated with a 100 percent incidence of VLUs.
In order to achieve proper compression therapy, Dr. Labovitz advocates for a “PLACE” approach. Pressure refers to the numerical value of the compression exerted. Layers indicate how one wraps the bandage, whether it is single-, double-, or multi-layered with layers overlapping by 50 percent. Components suggests that different materials may serve different but important functions such as absorption, padding or protection. Lastly, elastic properties of the material a clinician uses must be understood since each has unique characteristics that may help or hinder the treatment plan.
Returning to the issue of venous compression therapy in the presence of PAD, Dr. Labovitz discusses multiple studies providing pearls on the topic. In one study, Humphreys and coworkers successfully and safely employed compression therapy in patients with an ankle-brachial index (ABI) greater than or equal to 0.5, and recommended compression pressures of 15 to 25 mmHg if the ABI is between 0.5 and 0.85.5 Using digital systolic blood pressure as an indicator of peripheral perfusion, Top and colleagues found no significant difference in blood pressure when using compression for mixed etiology ulcers.6
Abu-Own and colleagues found that compression therapy increases total skin blood flow due to increased flow velocity.7 They noted that blood flow doubled with 20 to 30 mmHg of compression and skin circulation was not impaired at 50 to 60 mmHg. Comparatively, Partsch and colleagues found that with elastic compression therapy at 30 mmHg, there was normal perfusion at the level of the bandage but impeded perfusion at the toes.8 However, inelastic compression at 38 mmHg actually improved blood flow.8 Partsch and coworkers also found that intermittent pneumatic compression may benefit arterial flow.8
While multiple study authors agree that inelastic bandages could benefit those with mixed venous and arterial disease, Mosti and colleagues, in particular, suggests a treatment algorithm of an inelastic bandage of less than 40 mmHg for compression in patients with an ABI greater than 0.5 and venous pressure greater than 60 mmHg.9
Dr. Labovitz concludes that while compression therapy can be safe to use in patients with concomitant PAD, it is often not employed. He cites low patient compliance, inelastic bandage slippage and retention of heat and moisture as possible challenges to effective implementation of therapy. However, Dr. Labovitz says newer Velcro devices may provide some improvement in addressing these concerns. After considering the evidence, Dr. Labovitz advocates for an inelastic, high-stiffness compression dressing with more than one layer at a compression of less than 40 mmHg for these patients.
Keys To Diagnosing And Treating Patients With Critical Limb Ischemia
A team approach to managing critical limb ischemia (CLI), including expert podiatric and endovascular care, is vital, according to Ali Golshan, MD, MBA. He adds that the endovascular specialist should be one who is dedicated to the use of alternative access sites and is comfortable with care below the knee. Primary care medicine also plays a role for management of comorbid conditions and smoking cessation, notes Dr. Golshan.
A fellowship-trained interventional radiologist, Dr. Golshan recommends prompt vascular consultation when indicated. This consultation may include a quick evaluation with arterial duplex, possible cross-section computed tomography angiography (CTA) or magnetic resonance angiography (MRA) if there is complex iliac disease or an unclear ultrasound. When appropriate, he pursues timely angiography and one-stage multilevel revascularization. Dr. Golshan adds that establishing flow from the heart to the foot without interruption is key and angiosome-specific revascularization is even more desirable. He also recommends that vascular perform timely follow up after procedures to assess for wound healing and the potential need for any additional angiography.
Timely intervention at all levels of the team is crucial in order to preserve tissue, according to Dr. Golshan. He recommends both arterial and venous ultrasound in the evaluation of a patient with an ulcer. Dr. Golshan also agrees with Dr. Labovitz that mixed venous and arterial disease is extremely common. He advocates for treating the arterial disease first when CLI is present.
When specifically addressing inframalleolar disease, Dr. Golshan outlines an angiography techinique with antegrade ipsilateral access to the common femoral artery, depending on the patient’s body habitus. With a shorter and straighter path to the desired anatomy, this approach allows for angioplasty and atherectomy when necessary for resistant calcific lesions.
Who gets a bypass? Vincent Rowe, MD, states that patient comorbidities such as end-stage renal disease (ESRD) and diabetes, along with advanced age play key roles in determining which procedure is optimal. In addition to seeing an increase in the number of patients in their 80s in his practice in the last decade, Dr. Rowe also notes an increase in the prevalence of ESRD in his patients. Endovascular procedures are on the rise in the past two decades while open vascular procedures are decreasing, according to Dr. Rowe.9 However, he adds that residents are still learning the open revascularizations while also being taught the endovascular techniques.9
Dr. Rowe, a Professor of Clinical Surgery at the Keck School of Medicine of the University of Southern California, highlights the in-progress BEST-CLI study, which is being sponsored by the National Heart, Lung and Blood Institute.10 This prospective, randomized, multicenter, open-label trial currently has 2,100 patients at 120 clinical sites in the United States and Canada, notes Dr. Rowe. He points out that each patient will have at least one year of follow-up in order to compare treatment efficacy, functional outcomes and cost in patients with CLI undergoing the best open surgical or best endovascular revascularization.
All the faculty in this lecture track agree that angiosomes play a significant role in endovascular procedure selection. Tissue loss is important to consider from the standpoint of limb salvage and patient reserve is relevant in that frailty can be an issue in assessing perioperative risk. Dr. Rowe cites his experience with the Frailty Meter™ (Biosensics™), a wireless elbow flexion and extension test that enables one to assess patient frailty. Frailty is an emerging metric in determining health care outcomes and the concept of “prehabilitation” is evolving as a preventative measure, according to Dr. Rowe.
