Definitions of CLI vary, can be vexing
One of the challenges of treating critical limb ischemia is its definition. The definition of CLI has changed over time. Today, different medical societies use different definitions.
CLI was first formally defined in 1982 by the Working Party of the International Vascular Symposium, which aimed to define a condition in patients without diabetes with chronic ischemia as the major threat to a limb, and which defined CLI as ankle pressure < 40 mm Hg in patients with rest pain and < 60 mm Hg in those with tissue necrosis.
The Rutherford classification, developed in 1986 and revised in 1997, is based on clinical symptoms designed to characterize the severity of chronic limb ischemia. Patients with CLI may fall under category 4 (ischemic rest pain with ankle pressure < 40 mm Hg and flat or barely pulsatile ankle or metatarsal pulse volume recording or toe pressure < 30 mm Hg), category 5 (minor tissue loss with ankle pressure < 60 mm Hg and flat or barely pulsatile ankle or metatarsal pulse volume recording or toe pressure < 40 mm Hg) or category 6 (major tissue loss with the same criteria as category 5).
The TransAtlantic Inter-Society Consensus (TASC) Working Group released a consensus document including a CLI definition in 2000, updating it in 2007. In the 2007 document (TASC II), the recommended definition is “all patients with chronic ischemic rest pain, ulcers or gangrene attributable to objectively proven arterial occlusive disease.” This definition was adopted by the American Heart Association/American College of Cardiology in 2016 for a guideline on the management of patients with lower-extremity peripheral artery disease.
In 2014, the Society for Vascular Surgery (SVS) wrote that “the concept of a single dichotomous hemodynamic cutoff point for CLI no longer applies to the majority of patients encountered in current clinical practice” and dispensed with the term CLI in favor of “an objective classification of the threatened limb based on the degree of ischemia, wound extent, gangrene and infection.” The society developed the SVS Lower Extremity Threatened Limb Classification System based on grading of three major factors: wound, ischemia and foot infection (WIfI) along a four-point scale. The SVS WIfI system aims to create a more comprehensive classification of ischemic wounds akin to the tumor, node and metastasis (TNM) staging classification for cancer. – by Erik Swain
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