Limb ischaemia Flashcards
ARTERIES OF THE LOWER LIMB
i) when does the ext iliac become the femoral artery?
ii) what two arteries does the popliteal artery split into? where can each of these pulses be felt?
i) ext iliac passess under the inguinal ligament and becomes femoral
ii) popliteal > ant and posterior tibial
- ant felt on top of foot and posterior behind med malleolus
IMPORTANT TERMS
i) what is ischaemia? define absolute and relative ischaemia
ii) what is acute ischaemia? what are the signs of this?
iii) how long is it before chronic ischaemia is established?
iv) which type of chronic ischaemia is defined by gangrene and rest pain? which is defined by asymp and claudication?
i) ischaemia = deficiency in supply of blood flow to tissue bed
- absolute = insufficient perfusion to continue normal cellular processes (limb threatening)
- relative = insufficient perfusion to permit full function but ok at rest (life changing but not limb thretening)
ii) acute ischaemia - sudden occurence of absolute ischaemia
- 6Ps - pallor, pain, perishing cold, paralysis, paraesthesia, pulseless
iii) chronic ischaemia is insufficient perfusion >2weeks
- gangrene and pain at rest - absolute (critial)
- asymp and claudication - relative
NEUROSENSORY DEFICIT
i) what should be done if there is no evidence of neurosensory deficit?
ii) what should be done if there is NS deficit with limb staining (discoloured/bruised) and mottled discolouration?
iii) what is the first question to ask if there is NS deficit but there isnt limb staining or mottling? what two things should be done urgently?
i) no NS deficit - do imaging then early revascularisation
ii) NS deficit - non salvagable so amputate or palliate
iii) NS deficit - is the limb salvagable? if yes then do urgent CTA > revasc
CAUSES OF ACUTE LIMB ISCHAEMIA
i) what is ALI?
ii) name three embolic causes
iii) name a thombotic cause
iv) what may a popliteal thrombosis cause?
v) name three trauma causes
i) any sudden decrease in limb perfusion causing a potential threat to limb viability and life
ii) embolic > AF, endocarditis, proximal aneurysm
iii) thrombotic > rupture of an atherosclerotic plaque
iv) pop thrombosis can cause an anuerysm
v) trauma - fracture, disloc, knife wount, IVDU, iatrogenic
TREATMENT OF ACUTE ISCHAEMIA
i) how is heparin given? how is LMWH given?
ii) how should the foot be positioned?
iii) what imaging modality is useful in work hours? what the mainstay of imaging as its easy to obtain?
i) give heparin IV
give LMWH sub cut
ii) position the foot downwards (hang down)
iii) duplex US in work hours
- CT angio is mainstay as it is easy
EMBOLI
i) what is it?
ii) what is a sign of sudden onset absolute ischaemia? what is the most common cause?
iii) what happens in embolectomy?
iv) name four things that should be done post embolectomy? what should all patients recieve?
i) a mass that travels through the circulation and lodges in a blood vessel, arresting circulation
ii) sudden onset absolute ischaemia > full pulses on other side
- AF is the most common cause
iii) embolectomy > cut into artery and put a sling on surrounding arteries to arrest flow
- make a TV incision and pull out embolus
iv) hunt the cause, imagine proximal arteries, echo, 24 hours ECG
- all patients should be anti coagulated
THROMBOTIC DISEASE
i) name two things that may be seen in thrombotic disease?
ii) what usually happens? how do they rarely present?
iii) before what time period can thrombolysis clear a clot? what does this therefore allow for?
iv) what surgical approach may be taken?
i) may have history of claudication or missing contralateral pulses
ii) usually involves an acute clot on underlying atherosclerosis
- rarely present hyper acutely
iii) thrombolysis can clear an acute clot <2 weeks but better <1 week
- this allows angioplasty/stent of underlying plaque
iv) surgery usually involves bypass
TRAUMA
i) how should it be managed (3)
ii) is stenting often used?
iii) what may be done pre-emptively?
iv) what should be done in IVDU/infection
i) maintain flow with a shunt, fix bones then bypass
ii) stenting not often used in trauma
iii) should be fasciotomy pre emptively to stop compartment syndrome
iv) ligate rather than repair due to infection
COMPARTMENT SYNDROME
i) why does it happen?
ii) what is the main symptom?
iii) name two late signs
iv) what is the treatment?
i) when ischaemic muscle gets reperfused > muscle oedema > pressure in compartment goes up > microvascular compromise and muscle necrosis
ii) main symptom is intense pain especially to passive movement
iii) late signs are paraesthesia in the feet and pulseless
iv) do a fasciotomy > cut fascia to release pressure in teh compartment
CHRONIC ISCHAEMIA
i) what is it defined as?
ii) what is the main risk factor?
iii) name three drugs patients should be put on?
iv) what are early signs of trouble? (2)
v) when should you intervene?
i) ischaemia for >2weeks
ii) main RF is smoking
iii) patient on antiplat, statin even if normal cholesterol, ACEi
iv) early signs are nocturnal rest pain and reduced BP on lifting the foot
v) intervene only when short distance or life limiting (only when critical)
TREATMENT FOR CRITICAL ISCHAEMIA
i) what is the first option? why?
ii) what makes treatment less likely to work?
iii) what should be done if tissue loss is advanced and there is a low chance of revasc suceeding?
iv) in what situation should palliation happen?
i) first option > angioplasty +/- stent - lower risk and less likely to make worse
ii) long segment occlusion means less likely to work > do a bypass here
iii) amputation
iv) if frail
ANGIOPLASTY
i) what technique is used?
ii) what approach is taken to get into the lumen? what approach is taken i if the vessel is occluded?
iii) name two types of special stents that can be used
i) seldinger technique
ii) trans luminal > lumen
sub intimal > if lumen is occluded
iii) drug elution stents or covered stents
BYPASS SURGERY
i) what are the two main types? give an example of each
ii) what is usually used as a conduit?
iii) why may a femoro femoral crossover be used? how does it work? name a disadvantage of this
iv) where does an axillo bifemoral go from and to?
v) name two advanatages of using a vein? name two disadv of using plastic bypass?
i) anatomical (aorto bifemoral) and extra anatomical (femoro femoral crossover)
ii) vein as a conduit
iii) if patient isnt fit enough to have abdominal surgery
- borrows blood from the good side and tunnel to the bad side
- problem = patency isnt very good and high risk of infection
iv) from axillary artery below the clavicle > down the side of the chest > to the groin > femoral
v) vein - greater patency and less likely to become infected
- plastic - increased thrombosis and infection rates
SUMMARY
i) name four diseases that are affected by atherosclerosis?
ii) what approach should usually be taken to claudication?
iii) name four approaches to absolute ischaemia
iv) is intervention always necessary in relative ischaemia?
i) athero > peripheral, coronary, cerebral, renal disease
ii) claudication usually improves with non operational treatment > maintain with conservative mx unless a threat to life
iii) absolute > angioplasty, surgical revasc, amputation, palliation
iv) patient could be worse off with intervention in relative ischaemia
