Acute limb ischaemia

Question 1

Define Acute Limb Ischaemia

Answer 1

Any sudden decrease in limb perfusion that causes a (potential) threat to viability

Question 2

What are the causes of Acute limb ischaemia?

Answer 2

• **Embolisaton **(30%)
  
  • Cardiac (80%): AF, MI, ventricular aneurysm
  • Aneurysm (10%)
  • Embolisation of thrombus
• Acute Thrombosis (60%)
  
  • Atherosclerosis
  • Peripheral aneurysm
  • Graft occlusion
• Other
  
  • Dissection
  • Trauma

Question 3

What are risk factors for ALI?

Risk factors for Embolic & Thrombotic causes

Answer 3

• Sex: male
• Age : older
• Diabetes mellitus
• BP high
• Elevated cholesterol (hyperlipidaemia)
• Tobacco
• History of intermittent claudication (thrombosis)
• EMBOLIC
  
  • Cardiac issues
  • Aneurysms
• THROMBUS
  
  • Oral contraception
  • History of thrombosis
  • History of thrombophilic disorders (eg protein C or S deficiency)

Question 4

Outline features suggestive of Embolism & Thombosis

Answer 4

Embolism

• No history of claudication
• Cardiac signs: AF, MI

Thrombosis

• History of claudication
• No obvious source of emboli
• ‘More’ biltateral (reduced/ absent pulses in contralateral limb)

Question 5

What are the cardinal features of acute arterial occlusion?

Answer 5

6P’s

1. Pallor
2. Paraesthesia
3. Paralysis
4. Pain
5. Pulseless
6. Parishing with cold

• Acute onset
• Unilateral

Question 6

What is ichaemia-reperfusion syndrome and why is it relevent?

Answer 6

Revascularisation of a hypoxic tissue causes inflam. and oxidative injury systemically

• Neutrophils migrate and cause damage
• Limb swelling due to increased capillary permeability may cause compartment syndrome
• Leakage from damaged cells may cause acidosis and hyperkalaemia (leading to cardiac arrhythmias) and myoglobinaemia (leading to acute tubular necrosis)

Question 7

What are complications of ALI?

Answer 7

• Death (20%)
• Limb loss (40%) - severe ischaemia leads to irreversable tissue damage within 6h

Question 8

Outline the emergency management of ALI & treatment of all patients

Answer 8

Resusitation - Emergency admission

• 100% O2
• IV access +/- 1L crystalloid if dehydrated
• Opiate analgesia
• HEPARIN
  
  • ​5000IU unfractionated heparin IV bolus
  • Infusion of 1000IU/h
    
    • No contraindications
    • Recheck APTT in 4-6h
    • Target: 2-2.5x normal range

Question 9

Outline the investigations for ALI

Answer 9

Bloods

• FBC
  
  • Ischaemia aggravated by anaemia
• U&E
  
  • Kidney
• ESR
  
  • Inflammatory - giant cell arteritis, connective tissue disorders
• Troponin
  
  • Heart
• Clotting
  
  • Thrombophilia screen
• Glucose
  
  • Diabetes
• Lipids
• Group & save

Imaging

• CXR
• ECG (dysrythmias)
• Echo
• Aortic ultrasound
• Popliteal & femoral art ultrasound

Question 10

How do you establish the degree of urgency in ALI?

How do you determine if;

• Damage is irreversible
• Immediate treatment needed
• Prompt treatment after investigation’s needed

Answer 10

Limb viability assessment;

• Irreversible
  
  • Fixed skin mottling
  • Petechial haemorrhages
  • Woody hard muscles
• Imediate treatment
  
  • Muscles tender to palpation
  • Swollen
  • Loss of power/ sensation
• Prompt treatment after investigation
  
  • Pulseless
  • Pale & cold
  • Reduced cap refill

Question 11

Outline the definitive management of varying degree’s of severity

• Damage is irreversible
• Immediate treatment needed
• Prompt treatment after investigation’s needed

Answer 11

Irreversible

• Amputation inevitable & urgent (not emergency)

Immediate treatment needed

• To prevent systemic complication of muscle necrosis
  
  • Hyperkalaemia
  • Acidosis
  • Acute Renal Failure
  • Cardiac arrest
• Treatment
  
  • Surgery to revascularize limb & perform fasciotomies (prevent/ treat compartment syndrome)
  • Amputation if too advanced

Prompt treatment after investigation’s needed

• Continue heparinization
• Imaging
  
  • Angiogram (stop heparin 4h prior)
  • or Duplex/ CT angio
• Treatment
  
  • Thrombolysis
  • Angioplasty
  • Arterial surgery