Lower Limb Ischaemia Flashcards
what is acute limb ischaemia defined as
sudden decrease in limb perfusion that threatens the viability of the limb
what are the 3 main classifications that can cause acute limb ischaemia
-
Embolisation
- thrombus from proximal source travels distally to occlude artery e.g. AF, post MI, prosthetic valve, AAA. -
Thrombus in Situ
- atheroma plaque ruptures and thrombus is formed -
Trauma
- e.g. compartment syndrome, least common
signs + symptoms of acute limb ischaemia
the 6 P’s:
PAIN
PALLOR
PULSELESSNESS
PARATHESIA
PERISHINLGY COLD
PARALYSIS
Investigations for patient with acute limb ischaemia
Routine bloods including serum lactate to assess level of ischaemia
ECG
Doppler USS of both limbs followed by CT angiography
is acute limb ischaemia an emergency?
YES
-Complete occlusion will lead to irreversible tissue damage within 6 hours
surgical options for embolic cause of acute limb ischaemia
- embelectomy via fogarty catheter
- local intra-arterial thrombolysis
surgical options for thrombotic cause of acute limb ischaemia
- angioplasty +/- stent
- bypass
- local intra-arterial thrombolysis
what drug should be initiated in acute limb ischaemia
heparin
appearance of irreversible limb ischaemia
mottled non-blanching appearance with hard woody muscles
management of irreversible limb ischaemia
amputation
what is an important complication of acute limb ischaemia
reperfusion injury – a sudden increase in capillary permeability can result in:
- compartment syndrome
- release of substances from damaged muscle cells:
- K+ ions cause hyperkalaemia
- H+ ions causing acidosis
- Myoglobin – significant AKI
what is chronic limb ishaemia
peripheral arterial disease that results in symptomatic reduced blood supply to the limbs
most common cause of chronic limb ischaemia
atherosclerosis
risk factors for chronic limb ischaemia
smoking
diabetes
HTN
hyperlipidaemia
family hx
obesity
how does chronic limb ischaemia typically present
intermittent claudication - cramping pain in calf/thigh/buttock after walking a fixed distance and relieved by rest
what is Buergers test
involves lying the patient supine and raising their legs until they go pale, then lowering them until the colour returns
- the angle at which the limb goes pale is termed Buergers angle
- angle of <20 degress indiacates severe ischaemia
what is Leriche syndrome
form of peripheral arterial disease that affect the aoritc bifurcation
typically presents as buttock claudication + erectile dysfunction
what is ABPI
ABPI = ankle brachial pressure index
- measured bu taking BP from ankle + arm and calculating ratio
- usually BP is higher in the leg than the arm
- if blood flow to the leg is impaired, leg BP drops below arm BP
- the greater the drop the worse the blood flow
what ABPI score is normal
1-1.2
what ABPI indicates claudication
0.9-0.6
what ABPI indicates ischaemic rest pain
0.6-0.3
what ABPI score indicates critical ischaemia
<0.3
what is critical limb ischaemia?
how can is be clinically defined?
advanced form of chronic limb ischaemia.
Can be clinically defined in 3 ways:
- ischaemic rest pain > 2 weeks duration
- presence of ischaemic lesions/gangrene
- ABPI <0.3
how is diagnosis of chronic limb ischaemia made
clinical, with ABPI to confirm and quantify severity
what tests should be done as part of cardiovascular risk assessment for patients with chronic limb ischaemia
BP
blood glucose
lipid profile
ECG
What additional tests should be done in a patient <50 years old with no risk factors presenting with chronic limb ischaemia
thrombophilia screen
homocysteine levels
medical management of chronic limb ischaemia
lifesytle advice - smoking cessation, weight loss, exercise
statin - atorvastatin 80mg
anti-platelet - clopidogrel 75mg
diabetes control
management of critical limb ischaemia
urgent referral for surgical intervention
- angioplasty +/- stenting
- bypass grafting
what can cause a raised ABPI >1.2
Vessel calcification
- common in diabetes
In claudication affecting the buttocks, which artery is likely to be affected
iliac stenosis
