Limb Ischaemia Flashcards
What is acute limb ischaemia and what is the aetiology of this?
Sudden decrease in limb perfusion that threatens the viability of the limb
Three groups:
- Embolisation
- Thromus in situ
- Trauma
What are the clinical features of acute limb ischaemia?
SUDDEN ONSET 6 P’s
Pain
Pallor
Pulselessness
Paraesthesia
Perishingly cold
Paralysis
What are some causes of embolisation causing acute limb ischaemia?
Normal pulsatile contralateral limb is sign of embolic occlusion
- AF
- Recent MI with mural thrombus
- Symptomatic AAA
- Peripheral aneurysms
What are the different categories of acute limb ischaemia?
Later onset more likely there is irreversible damage to neuromuscular structures (>6h post symptom onset)
Rutherford Classification
What are some differentials for acute limb ischaemia?
- Critical chronic limb ischaemia
- DVT
- Spinal cord or peripheral nerve compression
How do you investigate suspected acute limb ischaemia?
- Routine bloods (lactate to assess level of ischaemia, thrombophillia screen if <50, G+S )
- ECG to look for AF
- Doppler US on both limbs then
- CT angiography
How is acute limb ischaemia managed short term?
Initial: Surgical emergency as irreversible damage in 6 hours. High flow O2, IV access, bolus heparin dose
Conservative (Rutherford I+IIa): prolonged course of heparin with regular clinical review and APTT monitoring
Surgical (Rutherford IIb onwards): if irreversible limb ischaemia (non-blanching and woody muscles) need urgent amputation.
Why do most acute limb ischaemia post-op patients need a high level of care?
Need HDU due to ischaemia reperfusion syndrome.
Sudden increase in capillary permeability can cause:
- Compartment syndrome
- Release of substances from damaged muscle cells (K+ hyperkalaemia, H+ acidosis, Myoglobin AKI)
What is the long term management of acute limb ischaemia?
- Reduce CVS mortality risk: weight loss, smoking cessation, regular exercise
- Antiplatelet agent: low dose aspirin or clopidogrel
- Treat any predisposing conditions: e.g AF
What are some risk factors for chronic limb ischaemia?
What is chronic limb ischaemia and what is it caused by?
Peripheral arterial disease that results in symptomatic reduced blood supply to limbs
Usually due to atherosclerosis (sometimes vasculitis) and commonly affects lower limbs
What are the clinical features of chronic limb ischaemia?
- Early sign is intermittent claudication (cramping pain in calf, thigh or buttock after walking a set distance and relieved by rest)
- Buerger’s Test: lie patient supine and raise legs until go pale then lower until colour returns, angle less than 20 degrees is severe ischaemia
What is Leriche Syndrome?
How is critical limb ischaemia defined?
- Ischaemic rest pain for greater than 2 weeks needing opiates
- Presence of ischaemic lesions or gangrene
- ABPI <0.5
How may critical limb ischaemia present on examination?
- Pale and cold limb
- Weak or absent pulses
- Limb hair loss
- Skin changes (atrophic skin, ulceration, gangrene)
- Thickened nails
What are the differential diagnoses for patients presenting with limb ischaemia?
- Critical limb ischaemia
- Spinal stenosis (Neurogenic claudication)
- Acute limb ischaemia
How is chronic limb ischaemia investigated and diagnosed?
Dx
- Clinical diagnosis
- ABPI confirms and quantifies severity
Further Ix
- Doppler US to find site of occlusio
- CT angiography or MRA
- CVS risk assessment (BP, Lipid profile, Blood glucose, ECG)
- <50 thrombophillia screen and homocysteine levels
How is chronic limb ischaemia managed?
Medical
- Life style advice
- Statin therapy (atorvastatin 80mg)
- Antiplatelet therapy (clopidogrel 75mg)
- Optimise diabetes control
- Supervised exercise programme to improve claudication distance
Surgical (risk factor modification discussed or supervised exercise failed to improve symptoms)
- Angioplasty with or without stenting
- Bypass grafting
- Amputation if gangrene
