Acute ischaemia: Lower limb Flashcards
Define acute limb ischaemia
Any sudden decrease in limb perfusion that causes a potential threat to liability. Features of severe ischaemia <2wk duration.
What are the signs and symptoms of acute limb ischaemia?
6 Ps: Pain (early) Pallor (initial), Mottling (later) Pulselessness Paraesthesia (early) Paralysis (advanced) Perishingly cold
Name 2 complications of acute limb ischaemia
Limb loss (40%) Death (20%)
What occurs if arterial circulation is not restored within 6 hours of onset of acute limb ischaemia?
Extensive tissue necrosis
What skin colour changes are seen with acute limb ischaemia? Explain their appearance
Initial: Pallor due to arterial spasm, causing insufficient arterial perfusion.
Later: Mottling (blue/purple reticular pattern) as skin fills with deoxygenated blood.
Describe the aetiology of acute lower limb ischaemia
Acute thrombosis in vessel with atherosclerosis (60%)
Emboli (30%)
Rare: aortic dissection, trauma, iatrogenic injury, popliteal aneurysm, intra-arterial drug use
Name 2 predisposing factors for acute thrombosis leading to acute limb ischaemia
Dehydration Hypotension Malignancy Polycythaemia (XS RBC) Inherited prothrombotic states
What clinical features are suggestive of acute thrombosis as the cause of acute limb ischaemia?
Previous Hx of intermittent claudication
No obvious embolic source
Reduced/absent pulses in contralateral limb
What is the commonest thrombotic cause of acute limb ischaemia?
Atherosclerosis
What are the embolic causes of acute limb ischaemia?
Cardiac (80%): AF, MI, ventricular aneurysm
Arterial aneurysm (10%)
Embolism of atherosclerosis in limb (rare)
What clinical features are suggestive of acute embolism as the cause of acute limb ischaemia?
Sudden onset of symptoms
Known embolic source
Absence of previous intermittent claudication
Normal pulses in contralateral limb
What investigations should be done in acute limb ischaemia?
FBC, U&E, clotting, glucose, troponin
Group and save
ECG - AF
ECHO - structural heart defects/ventricular aneurysm
CT - thrombus, emboli, dissection, aneurysm
Tumour markers
May consider Duplex USS or angriogram to locate stenosis.
Outline emergency treatment of acute limb ischaemia
100% oxygen
IV access - consider fluids if hypotensive
5-10mg morphine IM
Call for senior help
IV heparin (5000IU bolus + 1000IU/h infusion)
Start treatment for associated cardiac conditions (AF/CCF etc.)
Describe clinical features of irreversible acute limb ischaemia
Fixed mottling of skin
Petechial (small red/purple spot) haemorrhages in skin
Woody hard muscles
Describe clinical features of acute limb ischaemia that requires immediate treatment
Muscles tender/swollen on palpation
Loss of power
Loss of sensation
Describe clinical features of acute limb ischaemia that requires prompt treatment after investigation
Pulselessness
Pale
Cold
Reduced capillary refill
What is the definitive treatment of irreversible acute limb ischaemia?
Amputation
What is the definitive treatment of acute limb ischaemia that requires immediate treatment?
Revascularise limb
Fasciotomy - treat and prevent compartment syndrome
Consider amputation
What is the definitive treatment of acute limb ischaemia that requires prompt treatment after investigation?
Continue heparin
Angiogram or Duplex USS - locate disease
Thrombolysis/angioplasty/arterial surgery or all
How can the acute limb ischaemia be categorised following limb viability assessment?
Irreversible
Requires immediate treatment
Requires prompt treatment after investigation
What is a complication of revascularisation for acute limb ischaemia? How is this treated and prevented?
Reperfusion injury causing:
- Compartment syndrome
- Muscle necrosis
Treatment and prevention involves fasciotomies.
