Cardiovascular · Hard
This case is fictional and exists for study. It describes no real patient.
67 years · male
A 67-year-old male presents to the emergency department with a 4-hour history of severe, sudden-onset left leg pain. He reports a 6-month history of calf pain when walking short distances. He has a past history of hypertension and atrial fibrillation but stopped taking his prescribed apixaban three months ago. On physical examination, the left lower limb is pale and cold to the touch from the mid-calf distally. Sensation is diminished over the dorsum of the foot, and he exhibits mild weakness in dorsiflexing his left great toe. The left femoral pulse is palpable, but popliteal, posterior tibial, and dorsalis pedis pulses are absent. Right leg pulses are weak but palpable throughout. Arterial Doppler signals are inaudible at the left ankle.
Vital signs
- HR
- 104 bpm
- BP
- 148/88 mmHg
- RR
- 18/min
- Temp
- 36.7 °C
- SpO₂
- 97%
Examination findings
- Left mid-calf to foot pale and cold
- Reduced sensation over left foot dorsum and mild left great toe dorsiflexion weakness
- Absence of left popliteal, posterior tibial, and dorsalis pedis pulses
- Inaudible arterial Doppler signals in left ankle
Investigations
| Serum Lactate | 2.8 mmol/L | reference: 0.5-2.2 |
| White Blood Cell Count | 11.5 10^9/L | reference: 4.0-11.0 |
| Serum Creatinine | 105 µmol/L | reference: 60-110 |
Question 1 of 3
What is the most likely underlying diagnosis for this patient's acute presentation?
The patient presents with the classic '6 Ps' of acute limb ischaemia (Pain, Pallor, Pulselessness, Paresthesia, Paralysis/weakness, Perishingly cold) on a background of chronic peripheral vascular disease (claudication) and a cardiac embolic source (untreated atrial fibrillation). Phlegmasia cerulea dolens causes severe swelling and cyanosis, not pallor and loss of arterial pulses as the primary event. Lumbar radiculopathy does not cause cold, pale limbs or absent peripheral pulses. Acute compartment syndrome typically follows trauma or reperfusion and presents with severe pain on passive stretch without primary early loss of pulses.
Teaching point: Acute limb ischaemia presents with the 6 Ps and requires immediate recognition, especially in patients with atrial fibrillation or pre-existing arterial disease.
Question 2 of 3
Which of the following is the most appropriate immediate management step for this patient?
In acute limb ischaemia with neurological involvement (threatened limb), immediate administration of an IV unfractionated heparin bolus is essential to prevent thrombus propagation while urgent vascular surgical assessment is arranged for revascularisation (e.g., embolectomy, thrombolysis, or bypass). Delaying specialist referral for outpatient review or pre-referral imaging like CT angiography can lead to irreversible limb damage. Leg elevation and compression are strictly contraindicated in severe arterial insufficiency as they worsen perfusion.
Teaching point: Immediate management of acute limb ischaemia involves IV unfractionated heparin and urgent emergency vascular surgical referral.
Question 3 of 3
Based on the clinical findings, how is the severity of this patient's acute limb ischaemia classified according to the Rutherford classification?
The Rutherford classification categorises acute limb ischaemia severity: Category I (Viable, no sensory/motor loss), Category IIa (Marginally threatened, minimal sensory loss in toes, no motor loss), Category IIb (Immediately threatened, sensory loss extending beyond toes, mild-to-moderate motor loss such as toe weakness), and Category III (Irreversible, profound paralysis, anaesthesia, inaudible venous and arterial Doppler). Because this patient has motor weakness (toe dorsiflexion deficit) and sensory loss on the foot dorsum, it is Rutherford Category IIb.
Teaching point: The presence of motor deficit in acute limb ischaemia signifies a Rutherford Category IIb (immediately threatened) limb that requires emergency revascularisation.
Key learning points
- Acute limb ischaemia is characterized by the 6 Ps: Pain, Pallor, Pulselessness, Paresthesia, Paralysis, and Perishingly cold.
- Rutherford Class IIb acute limb ischaemia involves motor deficits and requires immediate emergency vascular surgical intervention to avoid amputation.
- Initial medical management of suspected acute limb ischaemia includes immediate intravenous unfractionated heparin to inhibit clot propagation.
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