Limb Salvage

SPY TECHNOLOGY IN LIMB SALVAGE

Many chronic wounds, including diabetic foot ulcers and venous leg ulcers, especially in older patients, fail to heal because of stenosis or occlusion of the feeder arteries supplying the local tissue in which the wound has occurred. This condition is known as peripheral arterial disease (PAD). In patients with diabetic foot ulcers, about 50% have PAD, which highlights the importance of vascular screening in such wounds. Globally, 202 million individuals were estimated to have the peripheral vascular disease in 2010, of whom 69.7% live in low-income or middle-income countries. The number of individuals with PAD also increased by 13.1% in high-income countries during the preceding decade.2

The American Diabetes Association reports that diabetes is the cause of 50%-67% of all non-traumatic lower extremity amputations in the United States. Major amputation is the 6th most expensive surgical procedure performed in the United States. In 2012, the cost of major amputation exceeded $10.6 billion, not including loss of productivity costs.6

PAD occurs when the buildup of fatty plaque, also known as atherosclerosis, interferes with blood flow in the vessels of the lower legs.  Atherosclerosis is often a result of diabetes. When adequate blood flow cannot be restored to the lower extremities and patients develop severe symptoms, amputation of the limb at some level may be considered. Minimizing the need for amputation or limiting the level by which an extremity must be removed is the goal for all patients requiring this life changing and often life threatening operation.

Jones and fellow researchers at Duke University reported that in a study of 186,338 patients, age 65 years and older with identified peripheral arterial disease, who underwent major LE amputation, the mortality rate was 13.5% at 30 days, 48.3% at 1 year, and 70.9% at 3 years. Subjects who underwent above knee amputation had a statistically higher hazard of death when compared with subjects who underwent LE amputation at more distal locations (HR with above the knee amputation.7

In 2012, researchers from the Southern Limb Salvage Association at the University of Arizona reported that preventing amputations in persons with lower extremity complications of diabetes is a complex endeavor, particularly in those with concomitant ischemia and tissue loss. Fluorescence angiography provides objective evaluation of perfusion status and tissue viability, an important indicator of the ability of the diabetic ulcer to heal. The researchers concluded, foot wounds can be healed only with an appropriate level of blood supply and because limb salvage efforts rely heavily on perfusion to the lower extremities, SPY technology will continue to be an important tool in preventing amputations from vascular deficienci.8

Clinical References

1. http://www.diabetes.org/diabetes-basics/statistics/infographics/adv-staggering-cost-of-diabetes.html#sthash.PiRhRUiA.dpuf

2. William W Li, Marissa J Carter, Elad Massiach, & Stephen D Guthrie, Vascular assessment of wound healing: a clinical review, Internaional Wound Journal, 2016

3. Colvard B, Itoga NK, Hitchner E, Sun Q, Long B, Lee G, Chandra V, Zhou W. SPY Technology as an adjunctive measure for lower extremity perfusion. J Vasc Surg 2016

4. Schlanger R. Clinical Case Update – Using Fluorescence Angiography to Help Assess Lower Extremity Wounds. Today’s Wound Clinic. Supplement. 2014.

5. 192. Li WW, Arnold J. Imaging of the Chronic Wound and the Emerging Role of Fluorescence Microangiography. Supplement – Today’s Wound Clinic. 2014.

6. Arnold J. Clinical Case Update – Using Fluorescence Microangiography for Timely Assessment of Wound Area Perfusion. Supplement to Today’s Wound Clinic. 2014.

7. Jones et al, High mortality risks after major lower extremity amputation in Medicare patients with peripheral artery disease. Am Heart J. 2013 May;165(5):809-15, 815.e1. doi: 10.1016/j.ahj.2012.12.002. e-pub http://www.ncbi.nlm.nih.gov/pubmed/23622919

8. Perry D, Bharara M, Armstrong, DG, Mills, J. Intraoperative Fluorescence Vascular Angiography: During Tibial Bypass. Journal of Diabetes Science and Technology. Volume 6, Issue 1, January 2012.