Limb ischaemia Flashcards
Acute limb ischaemia : Definition
Acute limb ischaemia is defined as the sudden decrease in limb perfusion that threatens the viability of the limb.
- Complete or even partial occlusion of the arterial supply to a limb can lead to rapid ischaemia andpoor functional outcomes within hours.
Acute limb ischaemia : Causes
1 . Embolisation
* whereby a thrombus from a proximal source travels distally to occlude the artery (most common)
* atrial fibrillation, post-MI mural-thrombus,
2 . Thrombosis in situ
* atheroma plaque in the artery ruptures and a thrombus forms on the plaque’s cap (presenting as acute or acute-on-chronic)
3 . Trauma
* including [compartment syndrome]
Acute limb ischaemia : Clinical features
Sudden onset occurance of the following symptoms :
> 6 hours post symptom development will leak to irreversible damage of the limb.
- Pain
- Pallor
- Pulselessness
- Paresthesia
- Perishingly cold
- Paralysis
Unilateral symptoms : consider embolism
Acute limb ischaemia : Investigations
- Bloods : Thrombophilia
- ECG : AF as source of embolus
- Doppler US : Both limbs
- CT angiography : if limb considered salvagable
Acute limb ischaemia : Management
Surgical emergency : Complete arterial occlusion will lead to irreversible tissue damage within 6 hours
1. Therapeutic dose of Heparin
Conservative management
Indic : Mild symptoms
Mx : Prolonged course of heparin
Surgical management
Indic : limb threatening or embolic cause
1. Embolectomy
2. Byplast surgery/Angiplasty
Irreversible limb ischaemia
Mx : Urgent Amputation
Acute limb ischaemia : Long term management
- Life style advice
- Initiate longterm antiplatelet therapy
Acute limb ischaemia : Complication
- Reperfusion injury : sudden increase in capillary permeability can result in
* Compartment syndrome
* Sudden muscle cell apoptosis and release of substances - causing hyperkalaemia, myoglobin in the blood
Chronic limb ischaemia : Definition
- Chronic limb ischaemia* is a form of peripheral arterial disease that results in a symptomatic reduced blood supply to the limbs.
- It is typically caused by atherosclerosis (rarely vasculitis) and will commonly affect the lower limbs
Chronic limb ischaemia : Clinical features
The clinical features of chronic limb ischaemia *depend on its severity
-
intermittent claudication
* a cramping-type pain in the calf, thigh, or buttock after walking a fixed distance
* that is relieved by rest within minutes.
2 . May develop into - Critical limb ischaemia
* Limb pain even at rest > 2 weeks
* Presence of ischaemic lesions or gangrene
* ABPI < 0.5
3 . Ulceration or Gangrenation
Chronic limb ischaemia : Examination
Examination : Colder, arterial ulcers, weak or absent peripheral pulse
Buerger’s test : lying the patient supine and raising their legs until they go pale and then lowering them until the colour returns (or even becoming hyperaemic).
Buerger’s angle - The angle at which limb goes pale
< 20 degrees : Severe ischaemia
Chronic limb ischaemia : Investigations
Clinical diagnosis
1 . Ankle-Brachial pressure index : quantifies severity of chronic link inchaemia
> 1.2 may be due to calcification or hardening of arteries
- Normal - >0.9
- Mild - 0.8-0.9
- Moderate - 0.5-0.8
- Severe - <0.5
2 . Doppler US
3 . CT Angiography or MR Angiography
Chronic limb ischaemia : Management
Medical management
* 80mg statin therapy
* Antiplatelet therapy : Clopidogrel 75mg
Surgical management
Indic : Critical limb ischaemia
* Angioplasty or Bypass grafting
Peripheral arterial disease: management
Amputation should be reserved for patients with critical limb ischaemia who are not suitable for other interventions such as angioplasty of bypass surgery.
Drugs licensed for use in peripheral arterial disease (PAD) include:
naftidrofuryl oxalate: vasodilator, sometimes used for patients with a poor quality of life
cilostazol: phosphodiesterase III inhibitor with both antiplatelet and vasodilator effects - not recommended by NICE
Venous ulceration
