According to the Fontaine classification, which stage of chronic limb ischemia is characterized by rest pain and tissue loss?

Explanation

## Fontaine Classification of Chronic Limb Ischemia **Key Point:** The Fontaine classification divides chronic limb ischemia into four stages based on clinical presentation and severity. Stage IV represents the most advanced form with rest pain and tissue loss (gangrene, ulceration). ### Fontaine Stages | Stage | Clinical Presentation | Ankle-Brachial Index (ABI) | Hemodynamics | | --- | --- | --- | --- | | **I** | Asymptomatic | > 0.9 | No significant stenosis | | **II** | Intermittent claudication | 0.5–0.9 | Mild to moderate stenosis | | **IIa** | Claudication > 200 m | — | Moderate stenosis | | **IIb** | Claudication < 200 m | — | Severe stenosis | | **III** | Rest pain | < 0.5 | Severe stenosis/occlusion | | **IV** | Rest pain + tissue loss (gangrene, ulcer, necrosis) | < 0.5 | Critical ischemia | **High-Yield:** Stage IV is the **critical limb ischemia (CLI)** stage and requires urgent intervention to prevent amputation. Rest pain alone (Stage III) may progress to tissue loss (Stage IV) if untreated. **Clinical Pearl:** The presence of tissue loss (gangrene, ulceration, or necrosis) is the defining feature that distinguishes Stage IV from Stage III. Patients with Stage IV PAD have a high risk of limb loss and require aggressive revascularization or amputation. **Mnemonic:** **FAINT** = Fontaine stages: **I** (asymptomatic), **II** (claudication), **III** (rest pain), **IV** (tissue loss). ### Clinical Implications - **Stage I–II:** Conservative management (exercise, risk factor modification) is often sufficient. - **Stage III–IV:** Urgent revascularization (endovascular or surgical) is indicated to prevent amputation.