Limb Ischaemia

Question 1

what is acute limb ischaemia?

Answer 1

acute event causing sudden deterioration in blood supply to a limb
<2 weeks

Question 2

presentation of acute limb ischaemia?

Answer 2

6Ps
- pain
- pallor
- pulseless
- paraesthesia
- perishingly cold
- paralysis
other limb is normal (no pain, normal pusles etc)

Question 3

causes of acute limb ischaemia?

Answer 3

embolic (e. fib, aneurysm, endocarditis)
atheroembolism
trauma (vessel transected or obstructed by swelling of surrounding tissue)
thrombosis
dissection
external compression (trauma to surrounding tissue)

Question 4

important history indicating acute limb ischaemia?

Answer 4

ask about timing (sudden onset = acute)
no symptoms prior (woke up with it etc)
contralateral side is normal
ask about cardiac symptoms and do cardiac exam (find source of ischaemia)
neuro history and exam (can less commonly have neuro cause)

Question 5

investigations in acute limb ischaemia?

Answer 5

bloods
- FBC
- U&Es
- CK
- coagulation screen
- group and save (will likely need surgery at some point)
- troponin 
ECG (check for MI or dysrhythmia)
CXR (underlying malignancy)
CT angio/duplex (everyone should get arterial imaging for planning of management)

Question 6

types of arterial imaging?

Answer 6

duplex US
CT angiogram
MR angiogram
catheter angiogram/DSA

Question 7

pros and cons of duplex?

Answer 7

quick, can be done at bedside
no radiation
gives info on flow
however it gives limited info, can only see snapshot of vessel not whole thing and is operator dependant

Question 8

pros and cons of CT angiogram?

Answer 8

quick and gives a lot of info about the vessel and surrounding vessels
however gives a lot of radiation, nephrotoxic contrast and not a lot of info about vessel flow

Question 9

pros and cons of MR angiogram?

Answer 9

not used much
can give good views if vessels very calcified but causes venous contamination, poor views through stents and nephrogenic systemic fibrosis

Question 10

pros and cons of catheter angiogram/DSA?

Answer 10

not used much
invasive, gives a lot of radiation and is nephrotoxic
does however allow you to progress directly to intervention

Question 11

stage 1 acute limb ischaemia?

Answer 11

0-4 hrs
white foot
painful
sensorimotor deficit
salvageable

Question 12

stage 2 acute limb ischaemia?

Answer 12

4-12 hrs
mottling
blanches on pressure
partly salvageable

Question 13

stage 3 acute limb ischaemia?

Answer 13

>12 hrs
fixed mottling
non-blanching
compartments tender/red/painful
non-salvageable

Question 14

management of acute limb ischaemia if diagnosed early?

Answer 14

surgical emergency
re-establish blood flow to limb
- surgical = emobolectomy +/- fasciotomy or bypass
- endovascular = targeted thrombolysis (mechanical or chemical)

Question 15

management of acute limb ischaemia if diagnosed late?

Answer 15

dead limb requires removing to prevent/control sepsis and aid mobility

• surgical = amputation
• conservative = palliation (if patient isnt fit for amputation, dead limb spreading too quickly etc)

Question 16

how does the presentation of acute on chronic limb ischaemia differ to that of acute?

Answer 16

it doesnt really

looks the same but patient has a background of claudication etc

Question 17

causes of acute on chronic limb ischaemia?

Answer 17

tends to be atheroembolic (several small emboli over long period of time or atheroslcerosis, cholesterol, plaques etc)
can have thrombosis in situ (arrest of blood flow at site of atherosclerotic stenosis)

Question 18

investigations in acute on chronic?

Answer 18

history and exam (same as acute)
same bloods as acute
urgent arterial imaging is needed (absolutely necessary as need to know site and length of occlusion)

Question 19

imaging in acute on chronic?

Answer 19

same as acute

CT angiogram most important

Question 20

management of acute on chronic?

Answer 20

bypass (most common)
thrombectomy/CDL + DSA
angioplasty/stent

Question 21

how is compartment syndrome related to limb ischaemia?

Answer 21

risk of occurring when blood returns to ischaemic site

Question 22

diagnosis of compartment syndrome?

Answer 22

clinical features
can use compartment pressures (>30 or <20 below diastolic BP)
usually have peripheral pulses present, normal systolic BP and 20 capillary pressure

Question 23

management of compartment syndrome?

Answer 23

fasciotomy

Question 24

what is critical limb ischaemia?

Answer 24

end stage peripheral arterial disease

narrowing of vessel lumen

Question 25

symptoms of critical limb ischaemia?

Answer 25

narrow vessel lumen means requirements of peripheral muscles are not met by blood flow resulting in short distance claudication

Question 26

classic pain in critial limb ischaemia?

Answer 26

pain at rest
worse at night
relieved by swinging foot over edge of bed
some might sleep in chair to help pain

Question 27

diagnostic criteria for critical limb ischaemia?

Answer 27

pain at rest for >2 weeks + tissue loss

ABPI <0.5 (normal around 1, but can be normal if heavily calcified vessels)

Question 28

examination features in critial ischaemia?

Answer 28

absent peripheral pulses
+ve buergers test (foot blanches on elevation then reperfuses when dangled over edge of bed)
hyperaemic foot “sunset”
can have arterial ulcers/tissue loss/necrosis

Question 29

diagnosis in critial limb ischaemia?

Answer 29

classic clinical features
arterial imaging (same as others, mainly CT)

Question 30

types of management of critial limb ischaemia?

Answer 30

conservative/medical (only when chronic but not yet critical)
endovascular
surgical

Question 31

conservative management of critical?

Answer 31

stop smoking
graded exercise (trains body to create collateral blood flow)
anti-platelets

Question 32

endovascular critial management?

Answer 32

angioplasty
stenting
revascularisation/recannalisation

Question 33

surgical management of critical?

Answer 33

endartectomy
bypass (using vein graft or artificial bypass)
amputation