Acute Lower Limb Ischaemia

Question 1

What is acute limb ischaemia?

Answer 1

Limited blood supply to a limb to the point that it causes ischaemia

Question 2

What are the causes of acute limb ischaemia?

Answer 2

Common - Peripheral Vascular disease, Embolism, Trauma, Compartment syndrome

Question 3

What will you ask about/find on history taking of acute limb ischaemia?

Answer 3

Symptoms: 6 P's
Pale
Pulseless
Painful
Paralysed
Paraesthesia - Tingling
Perishingly cold 
Fixed Mottling - Staining, blistering on limb (Late stage irreversible sign as the limb is refilled with deoxygenated blood) 

Risk Factors:
Cardiovascular Risk Factors
Peripheral vascular disease

Specific questions to ask in a history taking:
Speed of onset - Acute indicates embolism whereas chronic onset in previously diseased limb indicates thrombosis
Ask about sources of possible emboli – AF, Cancer, MI, Aneurism (aorta, femoral, or popliteal)
Time since it started - May affect treatment

Differentials:
Compartment Syndrome – History of trauma, Pain worsened by passive movement
DVT – Swollen tender limb, that is normally red/inflamed
Neurological Infarct causing paralysis – Other neurological signs or more than one limb affected

Question 4

What will you find on examination of a a patient with acute limb ischamiea?

Answer 4

Hands:
Feel pulse to assess for any arrhythmias that may predispose to clots (e.g. AF)
Chest:
Assess for any underlying cardiovascular risk factors or pathology that may predispose to an embolus
Legs:
Look for the 6 P’s
Do full neurological examination of the affected limb – Loss of sensation is common, but loss of motor function is a later sign
Ascertain up to which point the pulse is palpable - Femoral  Popliteal  Posterior Tibial  Dorsalis Pedis

Question 5

What investigations will you order acute limb ischamiea?

Answer 5

Bedside:
ECG – Looking for any arrhythmia e.g. AF that may predispose to embolism formation if no underlying cause identified
Capillary Glucose – Assessing cardiovascular risk factors

Bloods:
FBC – Anaemia can precipitate any ischaemia
ESR/CRP – Will be raised in arteritis
Lipids – Assessing cardiovascular risk factors
Thrombophilia screen If no underlying cause identified
Pre-operative bloods – U&E, Group and save, Clotting

Imaging:
Urgent Arteriography – To confirm diagnosis if in doubt
Echo - Looking for any underlying defect that may predispose to embolism formation in no underlying cause identified
Aortic/Popliteal/Femoral Ultrasound – Looking for an aneurism that may predispose to embolism formation in no underlying cause identified

Question 6

What is the treatment of acute limb ischamiea?

Answer 6

Medical:
High Flow O2
Heparin as soon as possible – Improves limb salvage rate
Morphine wih Metoclopramide – For the pain

Surgery:
Trauma– Reconstructive surgery
Acute Embolism – Intra-arterial thrombolysis (Urokinase) or Surgical embolectomy with fogarty catheter when that will take too long
Chronic Thrombosis – Angioplasty/Bypass surgery or Intra-arterial thrombolysis (urokinase),
In an Unviable Limb (Nerve damage, tissue death) - Amputation
After all surgery give post op heparin and treat the underlying cause