Acute Limb Ischaemia Flashcards
define acute limb ischaemia
sudden decrease in limb perfusion causing a potential threat to limb viability
causes of acute limb ischaemia
- embolism/ thrombosis
- arterial dissection
- trauma
- extrinsic compression
embolic/ thrombus causes of acute limb ischaemia
AF MI valvular disease acute thrombosis of popliteal aneurysm thrombus on atherosclerotic plaques
how can arterial dissection cause occlusion?
tear in the initima/media of the artery wall can lead to a flap forming which may occlude the artery
extrinsic compression causes of acute limb ischaemia
cervical rib
presentation of limb ischaemia (6 P’s) critical/ acute
pain pallor pulseless perishingly cold paraesthesia paralysis
pain in acute/ critical limb ischaemia
severe
sudden onset
resistant to analgesia
calf/ muscle tenderness with woody compartment indicating muscle necrosis (irreversible ischaemia)
pallor in acute/ critical limb ischaemia
empty veins that re-fill with stagnated de-oxygenated blood giving a mottled appearance
features 0-4 hours in acute limb ischaemia
white foot
painful
sensorimotor deficit
salvageable
features 4-12 hours in acute limb ischaemia
mottled
blanches on pressure
partly reversible
features >12 hours in acute limb ischaemia
fixed mottling
non-blanching
compartments tender/ red
paralysis
non-salvageable
diagnosis of acute limb ischaemia/ critical event
ABC
FBC, U&Es, CK, coag +/- troponin
ECG - MI, arrhythmias
CXR - underlying malignancy
management of salvageable limb in acute event
embolectomy
fasciotomies
thrombolysis
management in unsalvageable limb
palliation
amputation
once patient is anticoagulated what can they not have?
regional anaesthesia
what is an embolectomy?
surgical removal of embolus from inside an artery using an inflatable balloon (Fogarty balloon) to pull clot back
what is a fasciotomy?
when limb is successfully re-perfused, reperfusion injury can take place causing massive oedema in the muscle/ tissue within fascial compartments leading to compartment syndrome.
define reperfusion injury
reperfusion of suddenly blocked arteries leads to oedema (compartment syndrome) and release of toxins
toxins released in reperfusion injury
myoglobin
potassium ions
hydrogen ions
what will myoglobin affect?
renal function
clinical definition of critical limb ischaemia
- ischaemic rest pain >2 weeks
- presence of ischaemic lesions or gangrene
- ABPI <0.5
what is critical limb ischaemia?
advanced chronic limb ischaemia
what is acute-on chronic?
embolic event in patient with history of PAD
