Critically Ischaemic Leg

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DEFINITION
See also PVD
Threatened limb, secondary to vascular disease (stenosis, thrombosis, embolism),
Six Ps
- pain
- pallor
- pulseless
- parasthesia
- paralysis
- poikilothermia

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EPIDEMIOLOGY
Risk factors
Atherosclerosis risk factors.
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AETIOLOGY
Us. Emboli or Atherosclerosis
- either chronic
- or acute (thrombosis / embolism)
Also less commonly
- Vasculitis
- Sepsis
- Trauma
- Hematological disorders
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BIOLOGICAL BEHAVIOUR

Pathophysiology
Chronic plaques cause chronic ischaemia
Acute events result from thrombosis or embolism.

Natural history
This condition implies a threatened limb.


Complications
Ulcers
Gangrene.
Loss of limb.
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MANIFESTATIONS

Symptoms
Local
Chronic
Pain
Severe & burning
May be exacerbated by warmth
Often made better by leaving foot exposed
Lack of gravity worsens ischaemia
- pt wakes 2-3hrs after sleeping
- holds leg over bed and has a cigarette
- or sleeps in a chair.
This is indicative of limb-threatening ischaemia.

Acute
Pain in a cold leg.

Signs

Look, Feel, Move

Acute
Pain, pallor, paralysis, pulseless, paraesthesiae.
- AF and good contralateral pulses strongly favours embolism.
- past claudication, reduced contralateral pulses, sinus rhythm favours thrombosis.

Chronic
Observe
Pale
Venous guttering on elevation
Dependent rubor
- 'Buerger's test'
Ulcers / skin changes
-  affects distally - under the toes, or feet.
Palpate
Cool
Reduced/absent pulses


ABI
Non compressible >1.4
Normal 1-1.4
Borderline 0.91-0.99
Some arterial disease 0.8-0.89
Moderate arterial disease 0.5-0.8
Critical <0.5

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INVESTIGATIONS

Imaging
Early CT angiography.
Consider MR angiography is selected pts

Possible after revascularisation
- echo if emboli
- duplex USS

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MANAGEMENT

Q: When should endovascular versus surgical intervention be used for treatment?
A: On the basis of several randomized trials and recent case series, catheter-directed thrombolysis has the best results in patients with a viable or marginally threatened limb, recent occlusion (no more than 2 weeks’ duration), thrombosis of a synthetic graft or an occluded stent, and at least one identifiable distal runoff vessel.
Surgical revascularization is generally preferred for patients with an immediately threatened limb or with symptoms of occlusion for more than 2 weeks.

Q: What is reperfusion injury?
A: Reperfusion may result in injury to the target limb, including profound limb swelling with dramatic increases in compartmental pressures.
Symptoms and signs include severe pain, hypoesthesia, and weakness of the affected limb; myoglobinuria and elevation of the creatine kinase level often occur.
Since the anterior compartment of the leg is the most susceptible, assessment of peroneal-nerve function (motor function, dorsiflexion of foot; sensory function,  dorsum of foot and first web space) should be performed after the revascularization procedure.
The diagnosis is made primarily from the clinical findings but can be confirmed if the compartment pressure is more than 30 mm Hg or is within 30 mm Hg of diastolic pressure.
If the compartment syndrome occurs, surgical fasciotomy is indicated to prevent irreversible neurologic and soft-tissue damage.

Exam Answer
Definitive treatment depends on Rutherford classificaiton
Class III
- amputation, perhaps palliation
Class IIB
- immediate surgical exploration
- on table arteriography / balloon catheter embolectomy
Class IIa
- arteriography
- embolectomy or thrombolysis as indicated
Class I
- vascular risk prevention and workup by vascular surgeon as per sx.


Chronic Ischaemia
see notes

Embolic Event
Thombolysis
Embolectomy
- usually via common femoral artery
Followed by Heparin, Warfarin.


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