Limb Ischaemia Flashcards
what is acute limb ischaemia?
acute event causing sudden deterioration in blood supply to a limb
<2 weeks
presentation of acute limb ischaemia?
6Ps - pain - pallor - pulseless - paraesthesia - perishingly cold - paralysis other limb is normal (no pain, normal pusles etc)
causes of acute limb ischaemia?
embolic (e. fib, aneurysm, endocarditis)
atheroembolism
trauma (vessel transected or obstructed by swelling of surrounding tissue)
thrombosis
dissection
external compression (trauma to surrounding tissue)
important history indicating acute limb ischaemia?
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)
investigations in acute limb ischaemia?
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)
types of arterial imaging?
duplex US
CT angiogram
MR angiogram
catheter angiogram/DSA
pros and cons of duplex?
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
pros and cons of CT angiogram?
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
pros and cons of MR angiogram?
not used much
can give good views if vessels very calcified but causes venous contamination, poor views through stents and nephrogenic systemic fibrosis
pros and cons of catheter angiogram/DSA?
not used much
invasive, gives a lot of radiation and is nephrotoxic
does however allow you to progress directly to intervention
stage 1 acute limb ischaemia?
0-4 hrs white foot painful sensorimotor deficit salvageable
stage 2 acute limb ischaemia?
4-12 hrs
mottling
blanches on pressure
partly salvageable
stage 3 acute limb ischaemia?
>12 hrs fixed mottling non-blanching compartments tender/red/painful non-salvageable
management of acute limb ischaemia if diagnosed early?
surgical emergency
re-establish blood flow to limb
- surgical = emobolectomy +/- fasciotomy or bypass
- endovascular = targeted thrombolysis (mechanical or chemical)
management of acute limb ischaemia if diagnosed late?
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)
how does the presentation of acute on chronic limb ischaemia differ to that of acute?
it doesnt really
looks the same but patient has a background of claudication etc
causes of acute on chronic limb ischaemia?
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)
investigations in acute on chronic?
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)
imaging in acute on chronic?
same as acute
CT angiogram most important
management of acute on chronic?
bypass (most common)
thrombectomy/CDL + DSA
angioplasty/stent
how is compartment syndrome related to limb ischaemia?
risk of occurring when blood returns to ischaemic site
diagnosis of compartment syndrome?
clinical features
can use compartment pressures (>30 or <20 below diastolic BP)
usually have peripheral pulses present, normal systolic BP and 20 capillary pressure
management of compartment syndrome?
fasciotomy
what is critical limb ischaemia?
end stage peripheral arterial disease
narrowing of vessel lumen
symptoms of critical limb ischaemia?
narrow vessel lumen means requirements of peripheral muscles are not met by blood flow resulting in short distance claudication
classic pain in critial limb ischaemia?
pain at rest
worse at night
relieved by swinging foot over edge of bed
some might sleep in chair to help pain
diagnostic criteria for critical limb ischaemia?
pain at rest for >2 weeks + tissue loss
ABPI <0.5 (normal around 1, but can be normal if heavily calcified vessels)
examination features in critial ischaemia?
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
diagnosis in critial limb ischaemia?
classic clinical features arterial imaging (same as others, mainly CT)
types of management of critial limb ischaemia?
conservative/medical (only when chronic but not yet critical)
endovascular
surgical
conservative management of critical?
stop smoking
graded exercise (trains body to create collateral blood flow)
anti-platelets
endovascular critial management?
angioplasty
stenting
revascularisation/recannalisation
surgical management of critical?
endartectomy
bypass (using vein graft or artificial bypass)
amputation