27. Arterial insufficiency of the extremities, acute and chronic

Arterial insufficiency of the extremities: acute and chronic

Peripheral arterial disease (PAD) is usually caused by atherosclerotic narrowing or occlusion of arteries supplying the limbs. Risk factors include smoking, diabetes, hypertension, dyslipidaemia, chronic kidney disease and age.
Acute limb ischaemia is a sudden reduction in perfusion, commonly from embolism, in-situ thrombosis, graft/stent occlusion or trauma. Chronic limb-threatening ischaemia is advanced PAD with ischaemic rest pain, ulceration or gangrene.

Progressive plaque reduces blood flow reserve; exercise increases oxygen demand and causes intermittent claudication. Collateral vessels may develop but may not meet resting demand in advanced disease.
Acute occlusion causes abrupt oxygen deprivation, nerve and muscle dysfunction, cellular necrosis and reperfusion injury. Irreversible injury risk rises with duration and severity.

Intermittent claudication is reproducible exertional muscle pain relieved by rest, typically in calf, thigh or buttock depending on lesion level.
Chronic severe ischaemia causes rest pain (often worse at night/elevation), non-healing ulcers, distal gangrene, cool skin, hair loss, shiny skin and reduced pulses.
Acute limb ischaemia classically causes pain, pallor, pulselessness, paraesthesia, paralysis and poikilothermia. Sensory loss and motor weakness indicate a threatened limb and need immediate action.

Examine pulses from femoral to pedal, bruits, temperature, capillary refill, skin and wounds. Compare both limbs and assess neurological function.
Ankle-brachial pressure index (ABPI) is a first-line test; a low value supports PAD. Diabetes and calcified arteries can produce falsely high/non-compressible readings, so toe pressures or toe-brachial index may be needed.
Duplex ultrasound maps stenosis and flow. CT/MR angiography or catheter angiography defines anatomy when revascularisation is planned. Assess renal function and cardiovascular risk.

All PAD patients benefit from smoking cessation, supervised exercise, foot care, statin therapy, antiplatelet therapy when indicated, blood pressure/diabetes control and cardiovascular risk reduction.
Claudication is treated initially with best medical therapy and structured exercise. Revascularisation is considered for lifestyle-limiting symptoms despite treatment.
Chronic limb-threatening ischaemia requires urgent vascular referral, wound/infection care, analgesia and assessment for revascularisation by endovascular or bypass techniques. Amputation is considered when the limb is unsalvageable or infection/tissue loss cannot be controlled.
Acute limb ischaemia: give IV unfractionated heparin unless contraindicated, provide analgesia and urgently classify limb viability. Revascularisation may be surgical embolectomy/thrombectomy, bypass, endovascular thrombectomy or thrombolysis in selected cases.
After reperfusion, monitor for compartment syndrome, hyperkalaemia, acidosis, myoglobinuria and renal injury. Complications include ulceration, gangrene, infection, amputation, MI and stroke.