Preventing Amputation In Patients With Diabetes
- Volume 21 - Issue 3 - March 2008
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When it comes to peripheral arterial disease (PAD) or macrovascular disease, one can diagnose these diseases via the ankle-brachial index (ABI), segmental arterial pressures or pulse volume recordings. Clinical signs and symptoms might include gangrene or pallor on elevation, and rubor on dependency. Those with type 2 diabetes should have a screening for PAD every five years after diagnosis.24 Peripheral arterial disease is a marker for coronary artery disease and cerebrovascular disease. Those who are diagnosed with one disease usually have the other two. If the diagnosis is PAD, it would greatly benefit the patient to obtain a referral for cardiovascular risk reduction.
If an ulcer is present and vascular disease is significant, critical limb ischemia (CLI) is the diagnosis. Peripheral arterial disease is a serious risk factor for limb amputation in the presence of a foot wound.3 Patients with PAD or CLI require a consultation by a vascular surgeon to determine if an endovascular procedure or open bypass can restore flow.
One can investigate microvascular function via transcutaneous oxygen measurement, the OxyVu (HyperMed) or skin perfusion pressure. These measures can predict wound healing and the level of amputation.
How To Detect And Treat Infected Ulcers In The Diabetic Foot
Infection is often the coup de grace that precipitates an amputation. Infection is a clinical diagnosis that is based on the presence of two or more of the following: purulence, erythema, tenderness/pain or warmth.25 Laboratory assessment is of little value in diagnosing a diabetic foot infection. If you suspect an infection, you can be fairly confident that gram-positive organisms are the main pathogens. If the infection is mild, in which the erythema extends less than 2 cm, one can utilize empiric antibiotics to cover gram-positive organisms and obtain a tissue specimen for culture and sensitivity. Physicians can also adjust or narrow antimicrobial therapy based on the culture results.
As the incidence of methicillin-resistant Staphylococcus aureus (MRSA) is increasing, one should consider risk factors for MRSA such as previous MRSA infection, a history of multiple antibiotic usage and/or a history of hospitalization or institutionalization.26,27 If there are one or more risk factors present and the infection is moderate or severe, one should begin “de-escalation therapy” with vancomycin, linezolid (Zyvox, Pfizer) or tigecycline (Tygacil, Wyeth). After getting the culture and sensitivity reports, physicians can narrow the antibiotic spectrum.
If the infection is moderate or severe, hospitalization and surgery may be necessary to limit the spread of the infection. Intravenous antibiotics are often necessary in these cases and can be broad-spectrum. However, gram-positive bacteria are still generally the major causative organisms.
Recognizing The Realities Of Amputation
Amputation is often the unfortunate preventable end effect of the aforementioned pathway. The higher the level of amputation, the more energy is required for ambulation with the prosthesis.28 The five-year mortality rate after diabetes-related lower extremity amputation is nearly 50 percent. This mortality rate is higher than many types of cancers.29 About half of amputees suffer a serious lesion on the contralateral limb within two years.30 Lower extremity amputation often results in disability and a loss of independence. Amputation is often more costly than limb salvage.31,32
Given these data, podiatrists should limit amputations to cases of life-threatening infection, non-reconstructible ischemia or an uncorrectable deformity. Podiatric physicians can salvage most limbs with a combination of surgery and offloading.