# Acute Limb Ischaemia > NEET-PG Surgery notes on acute limb ischaemia: six Ps, Rutherford categories, heparin first, Fogarty embolectomy, fasciotomy and reperfusion injury. - Canonical URL: https://prepelephant.com/topics/neet-pg/surgery/acute-limb-ischaemia - Exam / course: NEET-PG · Subject: Surgery - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Acute Limb Ischaemia", PrepElephant, https://prepelephant.com/topics/neet-pg/surgery/acute-limb-ischaemia ## Direct answer Acute limb ischaemia is a sudden fall in limb perfusion that threatens viability, recognised by the six Ps — pain, pallor, pulselessness, paraesthesia, paralysis and perishingly cold — with sensory then motor loss marking the clock. Most cases follow embolism from the heart in atrial fibrillation or after myocardial infarction, emboli lodging at bifurcations, the common femoral artery the classic site; thrombosis of a pre-existing plaque or graft occlusion accounts for most of the rest. Management begins at the bedside with intravenous heparin, not imaging: a profoundly threatened limb goes straight to theatre for Fogarty balloon catheter embolectomy, with fasciotomy protecting the revascularised limb and reperfusion injury — hyperkalaemia, acidosis, myoglobinuria — the life-threatening aftermath. ## What you must remember - **Six Ps:** pain, pallor, pulselessness, paraesthesia, paralysis, poikilothermia — pain and paraesthesia are early, dense motor loss with fixed mottling is late and ominous. - **Rutherford acuity:** category I viable (not immediately threatened), IIa and IIb threatened (IIb requires urgent revascularisation), III irreversible — the category decides theatre versus observation. - **Embolic versus thrombotic:** embolus — abrupt onset, atrial fibrillation or recent infarct, no claudication history, contralateral pulses normal; thrombosis — claudication history, bilateral disease, more collaterals and a less dramatic onset. - **First drug, not first test:** intravenous unfractionated heparin bolus on suspicion, reducing propagation and microembolisation while the pathway proceeds. - **Fogarty embolectomy:** balloon catheter extraction through a femoral arteriotomy under local anaesthesia, with on-table angiography to confirm run-off; catheter-directed thrombolysis is the alternative for graft occlusion, late presentation or smaller-vessel thrombosis, contraindicated when the limb is profoundly threatened. - **Fasciotomy:** prophylactic two-incision four-compartment fasciotomy of the lower leg after prolonged ischaemia or following restoration of flow, because reperfusion oedema closes the compartments. - **Reperfusion injury:** washed-out potassium, lactate and myoglobin threaten rhythm and kidneys — hydrate, alkalinise urine, treat hyperkalaemia and monitor urine for myoglobin. - **Aftermath:** find the source (echocardiography, rhythm assessment), anticoagulate embolic disease, and accept that a dead muscle bed makes primary amputation safer than futile revascularisation. ## First hours decide the limb At 2 a.m. a 70-year-old with atrial fibrillation, inadequately anticoagulated, wakes with a cold, white, painful right leg. Examination: no femoral pulse on the right, brisk on the left; the foot is mottled to the ankle, sensation reduced to light touch, toe movement preserved — Rutherford IIa, threatened but salvageable. Heparin is given as the cannula goes in; a bedside Doppler confirms absent signals; CT angiography shows a common femoral occlusion with no distal run-off opacification. Within the hour she is on the table: local anaesthesia, transverse femoral arteriotomy, Fogarty catheter passed proximally and distally, clot extracted until back-bleeding and inflow are restored, on-table angiogram confirming three-vessel run-off. Because more than six hours passed before reflow, a two-incision four-compartment fasciotomy protects the leg. The next 24 hours belong to the intensivist: urine output, potassium, acid-base and myoglobin, because the heart and kidneys now carry the danger. Echocardiography later finds the left atrial appendage source, and lifelong anticoagulation is prescribed. ## Decisions that save life over limb The exam vignette with the highest yield is the late, numb, paralysed limb with fixed skin staining: revascularising several hours of dead muscle floods the circulation with potassium and myoglobin and kills the patient — primary amputation, or sometimes delayed revascularisation with open amputation, is the disciplined answer. The second decision-point is imaging: CT angiography is for the stable patient with time; the clearly threatened limb goes to theatre on clinical grounds, with on-table angiography available. Third, heparin precedes everything and continues through the pathway — candidates who image before anticoagulating fail the stem. Fourth, remember the source workup: an embolus demands echocardiography, rhythm study and long-term anticoagulation, and a thrombosed native artery demands best medical therapy plus consideration of definitive revascularisation later. Fifth, compartment syndrome is a post-revascularisation disease: the limb that was ischaemic and then reflown is the limb that swells, so prophylactic fasciotomy accompanies revascularisation after prolonged warm ischaemia — and the fasciotomy must open all four compartments through two incisions. ## Frequently asked questions ### What are the six Ps of acute limb ischaemia? Pain, pallor, pulselessness, paraesthesia, paralysis and perishingly cold — with paraesthesia progressing to paralysis marking increasing threat. ### Which is the commonest source of peripheral arterial emboli? The heart — atrial fibrillation and post-infarction mural thrombus dominate, with valves and cardiac tumours contributing less often. ### What is the immediate management before any imaging? Intravenous unfractionated heparin bolus on clinical suspicion, to limit clot propagation while resuscitation and the diagnostic pathway proceed. ### When is primary amputation preferred over revascularisation? In Rutherford category III irreversibly ischaemic limbs with fixed neurological loss and muscle rigidity, where restoring flow releases lethal potassium and myoglobin. ### Why is fasciotomy performed after embolectomy? Reperfusion oedema raises compartment pressures after flow is restored, so prophylactic four-compartment fasciotomy prevents the secondary injury that would otherwise destroy the salvaged limb.