Acute Limb Ischaemia

Question 1

What is the definition of acute limb ischaemia?

Answer 1

Sudden decrease in limb perfusion that threatens the viability of the limb in patients who present w/in 2/52 of the acute event
Decrease in perfusion is usually d/t sudden cessation of blood supply and nutrients to metabolically active tissues of the limb - may be in the setting of already narrowed vessel lumen or in normal lumen

Question 2

What are some DDx for acute limb ischaemia?

Answer 2

Acute DVT: phlegmasia cerulean dolens
Blue toe syndrome
Purple toe syndrome
Venous insufficiency
Venous occlusion
Acrocyanosis

Question 3

What are some causes of acute limb ischaemia?

Answer 3

Arterial embolism
Acute thrombosis
Arterial trauma
Dissecting aortic aneurysm

Question 4

What are the most common sites in which emboli lodge?

Answer 4

Bifurcation of the femoral artery (most common site)
Trifurcation of the popliteal artery
Aortic bifurcation
External and internal iliacs
Arm

Question 5

Briefly discuss the pathophysiology of acute limb ischaemia

Answer 5

tissues affected = nerves, mm, skin and bone (most to least sensitive); thus, early signs of ischaemia = pain and numbness, and mm paralysis as well as skin changes = later. Lower limb can survive abt 6-8hrs in an ischaemic state before injury => irrev

Question 6

How does a pt w/ acute limb ischaemia present?

Answer 6

6 P's
Pain
Paraesthesia
Pallor
Pulselessness
Paralysis

Question 7

How do you assess the severity of acute limb ischemia?

Answer 7

3 categories:
viable - no immediate threat of tissue loss
threatened - salvageable if re-vascularised promptly
non-viable - limb can’t be salvaged and has to be amputated, no emergency to operate. Patient may require revacularization to allow lower amputation or help amputation to heal

Question 8

How does one differentiate between embolic and thrombotic causes of ischaemia?

Answer 8

Embolic:
identifiable source present - AF, AMI
no claudication hx
contralateral pulses present, white limb (no blood)
On angiography: minimal atherosclerosis, sharp cut-off, few collaterals

Thrombotic:
Less common
+ve claudication hx
Contralateral pulses diminished, dusky limb (collaterals still supplying limb)
On angiography: diffuse atherosclerosis, irregular cut-off, well-developed collaterals

Question 9

How does one manage acute limb ischaemia?

Answer 9

1) Doppler U/S
2) Pre-operative investigations
3) Early anticoagulation
4) Measures to improve existing perfusion
5) Surgical emergency requiring active intervention
6) Post-operative anticoagulation w/ heparin +/- vasodilators if have vasospasm
7) KIV fasciotomy to prevent compartment syndrome
8) Tx other assoc conditions (CHF, AF)

Question 10

What preoperative investigations are done for a pt w/ acute limb ischaemia?

Answer 10

FBC, U&E/Cr, PT/PTT, GXM
CXR and ECG >40yo
Cardiac enz if suspected AMI
Angiogram in pts w/ viable limb

Question 11

What are the tx options for acute limb ischaemia?

Answer 11

Open Surgical Revascularization:
Embolectomy/Thrombectomy
Endarterectomy
Bypass Grafting
Fasciotomy
Primary Amputation

Endovascular Revascularization:
Thrombolysis
Angioplasty
Stenting

Question 12

What are the contraindications for intra-arterial thrombolysis +/- angioplasty?

Answer 12

Absolute:
CVA w/in past 2mo
Active bleeding/recent BGIT past 10 days
Intracranial haemorrhage/vascular brain neoplasm/neuroSx past 3 mo

Relative:
CPR past 10 days
Major Sx/trauma past 10 days
Uncontrolled HT

Question 13

What are some complications of emergent embolectomy?

Answer 13

Reperfusion Injury
Rhabdomyolysis
Compartment Syndrome