Acute Limb Ischemia Medical Slides

Present the four categories with treatment implications: Category I (Viable) — no sensory/motor deficit, audible arterial Doppler signals, not immediately threatened, allows time for angiography and planned intervention. Category IIa (Marginally threatened) — minimal sensory loss (toes), no motor deficit, inaudible arterial Doppler — urgent revascularization needed. Category IIb (Immediately threatened) — sensory loss beyond toes, mild-moderate motor deficit, inaudible arterial Doppler — emergent revascularization (catheter-directed thrombolysis if onset <14 days, surgical embolectomy if embolic). Category III (Irreversible) — profound sensory/motor loss, muscle rigor, no Doppler signals — amputation (revascularization risks fatal reperfusion injury).

Present the clinical distinction: Embolic — sudden onset (seconds to minutes), no prior claudication, known AF or recent MI, contralateral limb has normal pulses, angiography shows sharp cutoff with minimal collaterals. Thrombotic — more gradual onset (hours to days), history of claudication/PAD, atherosclerotic risk factors, contralateral limb may have diminished pulses, angiography shows diffuse disease with some collaterals. This distinction matters: embolic → surgical embolectomy (Fogarty catheter) is often preferred; thrombotic → catheter-directed thrombolysis or bypass may be needed due to underlying stenotic disease.

Present the reperfusion cascade: ischemic tissue accumulates lactate, potassium, and myoglobin. Upon revascularization: systemic release causes hyperkalemia (cardiac arrest risk), metabolic acidosis, myoglobinuria (rhabdomyolysis → AKI). Compartment syndrome develops in 10-20% post-revascularization. Management: pre-revascularization sodium bicarbonate, aggressive IV hydration (200-300 mL/hr targeting UOP >200 mL/hr), monitor serum K+ and CK, four-compartment fasciotomy if compartment pressure >30 mmHg or within 30 mmHg of diastolic BP. Mannitol may reduce compartment pressures and promote osmotic diuresis.