A 68-year-old man with 5 hours of acute right leg ischaemia and no interventional radiology until morning
A 68-year-old man with atrial fibrillation (not anticoagulated for 5 days, having run out of apixaban) presents at 02:00 with 5 hours of severe right leg pain that began while watching television. The leg is pale to mid-thigh, the foot is mottled, and he cannot feel light touch over the first dorsal web space. There is no dorsalis pedis or posterior tibial pulse, and the popliteal pulse is absent; the femoral pulse is present. Ankle Doppler signals are not audible. He can weakly dorsiflex the toes against resistance, and his calf is soft. He takes metoprolol and ramipril; there is no history of arterial bypass or claudication. Serum potassium is 5.1 mmol/L, creatinine 130 µmol/L, creatine kinase 1,100 U/L. The on-call anaesthetist is in theatre with a ruptured aneurysm and the vascular consultant is 40 minutes away. The hospital has CT angiography overnight but no interventional radiology until 08:00.
1. Grade the severity of this limb using a recognised clinical classification, and explain which findings decide the grade and which do not.
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Rutherford class IIb - immediately threatened. The grade rests on the neurological findings. Rest pain, absent ankle Doppler signals and sensory loss over the first web space would put him at best in class IIa, but demonstrable motor weakness (weak toe dorsiflexion against resistance) is the discriminator that makes this IIb. Class III, irreversible ischaemia, requires anaesthesia, paralysis and muscle rigor in a limb no longer worth revascularising; he still has some dorsiflexion and a soft calf, so the limb is salvageable. Five hours of ischaemia sits inside the window in which muscle infarction is still incomplete, so the grading is decisive rather than academic: IIb mandates revascularisation within hours, not an morning list.
What does not decide the grade: the mottling, the pallor, the ankle–brachial index (unreliable and irrelevant here), the potassium of 5.1 and the CK of 1,100 U/L. Those reflect the duration of ischaemia and the risk of reperfusion injury, not reversibility. Note also the anatomical level - femoral pulse present, popliteal absent - which suggests a common femoral or popliteal embolus, i.e. embolectomy territory rather than a bypass problem.
Class IIb therefore commits you to immediate surgical revascularisation with systemic heparinisation, and to anticipating reperfusion injury and fasciotomy, rather than to duplex, observation or thrombolysis (a class IIa option).
2. Set out your orders and decisions for the next 30 minutes, including what you will deliberately not do, and justify each with the underlying physiology.
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Immediate priorities:
- Give intravenous unfractionated heparin now - 80 U/kg bolus then infusion. It does not lyse the clot, but it prevents proximal propagation and fresh distal thrombus in the run-off, which is what converts a salvageable limb into an unsalvageable one.
- Analgesia (titrated IV opioid), nil by mouth, two large-bore cannulae, cross-match 4 units, ECG, baseline CK and potassium, hourly urine output.
- Keep the limb dependent at room temperature. Do not elevate, apply heat or compress it: elevation reduces perfusion pressure in a limb whose collateral bed is already maximally dilated by hypoxia.
- Call the consultant now and book theatre. Ask anaesthesia for a local or regional technique if general anaesthesia would delay embolectomy - a common femoral cut-down under local anaesthetic takes 20 minutes.
- Do not send him for CT angiography. The diagnosis and the level are clinical, the grading already demands operation, and a 40-minute scan delays reperfusion without changing the plan. On-table angiography after embolectomy is the useful study.
- Do not use catheter-directed thrombolysis. It is for class IIa limbs, takes 12–24 hours, and there is no interventional radiology until 08:00.
Hold apixaban; restarting anticoagulation is decided once haemostasis is secure and the cause (uncontrolled AF) is addressed.
3. The embolectomy is completed at 05:30 and a good Doppler signal returns. What do you monitor for, and on what grounds would you take him back to theatre?
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Anticipate reperfusion injury and compartment syndrome. Reperfusion delivers oxygen to ischaemic muscle, generating free radicals and calcium influx, so cells swell, rhabdomyolysis occurs and myoglobin is released. Orders: hourly urine output above 1 mL/kg/h, intravenous crystalloid, CK every 6 hours (a rising CK above about 5,000 U/L predicts renal injury), potassium, bicarbonate, creatinine, continuous ECG, and alkalinisation of urine with sodium bicarbonate if the CK is climbing. Hyperkalaemia and myoglobinuric acute kidney injury are what kill these patients, not the leg.
Return to theatre for:
- A tense, swollen calf with pain on passive ankle dorsiflexion or new sensory loss - clinical signs of compartment syndrome. Palpable pedal pulses do not exclude it, and an absent pulse in a tense calf is a late sign.
- Prophylactic four-compartment fasciotomy through medial and lateral incisions is reasonable at the time of revascularisation when ischaemia has exceeded 6 hours, or immediately if the leg is tense on waking.
- No improvement, or re-occlusion on Doppler - re-explore and repeat embolectomy with on-table angiography; missed popliteal trifurcation thrombus is common.
- Non-viable muscle at fasciotomy (grey, non-contracting) requires debridement, and if a whole compartment is dead, primary amputation rather than repeated futile washes.
Start therapeutic anticoagulation once haemostasis is secure, and arrange rhythm review and long-term anticoagulation for the AF.