Acute Limb Ischaemia Flashcards
(51 cards)
Define embolism?
-mass of material traveling through blood vessels and lodging at bifurcations
Define thrombosis?
-formation of blood clot in situ
What are the sources of embolism?
- Cardiac 80-90%
- Arterial
- Iatrogenic from coils
Define acute limb ischaemia?
- sudden decrease in limb perfusion that poses a risk to limb viability
- usually less than 2 weeks
Where are the common sites where emboli lodge?
- Femoral artery bifurcation- 36%
- Popliteal artery trifurcation- 15%
- Aortic trifurcation-22%
- External and internal iliac arteries-22%
- Arm-14%
What are the causes of cardiac emboli?
- atrial fibrillation-70%
- myocardial infarction with left ventricular mural thrombosis-20%
- mechanical valves
- endocarditis
- ventricular aneurysm
What are the causes of arterial emboli?
- artherosclerosis
- mural thrombosis from aneurysm
What is most likely to cause acute limb ischaemia between an embolus and thrombosis?
- Embolus
- This is because when it comes to thrombosis there has been time for collaterals to form and so it is less severe
How can trauma cause acute limb ischaemia?
-The development of arteriovenous-fistula leads to shunting of the blood away from the limb
How can dislocations and fractures cause acute limb ischaemia?
-by the stretching of the arteries, the intima tears and the media and the adventitia stays intact because they have elastin
What is affected first by ischaemia?
Nerves and the reason why we feel pain and numbness first
What is affected last?
- muscles
- bones
- skin
How long can the limb survive before the ischaemia is irreversible?
6-8 hours?
What are the 6 P’s?
- Pain
- Pallor
- Paraesthesia
- Pulselessness
- Paralysis
- Perishingly cold
How does pain present in these patients?
- The pain is distal and then moves proximally
- the pain decreases as ischaemia develops further
How does paraesthesia present in these patients?
- is an early
- light tough>vibration>proprioception>(late)deep pain>pressure sense
How does pallor present in these patients?
- starts as pink discoloration even if pale
- it then becomes marble white
- then becomes gangrenous(black)
What is a mottled colour?
White with blue discolouration
How do we check for pulselesness?
- make sure we get a handheld Doppler an compare the veins and arteries
- compare to other nerves
How do you check for viability?
- make a cut and check for shiny and twitching (viable muscle)
- if dull with no twitching then not viable
3 degrees of severity:
- Viable: no immediate threat of tissue loss
- Threatened: salvageable if revascularised
- Non-viable: needs to be amputated because it cannot be salvaged
What does the severity of limb ischaemia depend on?
- Duration
- How big the obstruction is
- Whether there are collateral arteries around the obstruction or not
- the location
What are the characteristics of a viable limb?
- Pain: mild
- Capillary refill: intact
- Motor deficit: none
- Sensory deficit: none
- Arterial Doppler: audible
- Venous Doppler: audible
- Treatment: urgent work up
What are the characteristics of threatened limb?
- Pain: severely painful
- Capillary refill: delayed
- Motor deficit: partial
- Sensory deficit: partial
- Arterial Doppler: absent
- Venous Doppler: present
- Treatment: emergency surgery