Introduction
Acute limb ischaemia occurs when there is blockage of a peripheral artery, either from a thromboembolism, or sometimes from an embolic plaque. It frequently occurs on a background of peripheral vascular disease.
As the MI is to coronary artery disease, acute limb ischaemia is to peripheral vascular disease
- Thrombus in situ – 40%
- Emboli – 38%
- Angioplasty occlusion – 15%
- Trauma
- Compartment syndrome – rare
Signs and Symptoms
Classically, the SIX P’s of acute limb ischaemia
- Pulseless
- Paraesthesia
- Pain – muscles also become tender to palpation after about 6-8hours
- Paralysis
- Pallor
- Perishing cold
- Fixed mottling of the skin implies irreversibility
- BEWARE – hot red leg may sometimes be present, which can result in misdiagnosis of gout or cellulitis
Diagnosis
You can roughly localise the blockage by locating the bifurcation distal to the last palpable pulse.
Diagnosis is clinical
Treatment
- It is an EMERGENCY!
- 22% of cases are fatal
- 16% of cases result in amputation
- Thrombolytic agent e.g. tissue plasminogen activator (tPA)– most effective when given via local arterial catheter (Fogarty Catheter), particularly for occlusions <2 weeks. Therapy is usually given via the catheter for 8-24hr
- Open surgery / angioplasty – DON’T BE AFRAID TO DO THESE! – equally, don’t be afraid to do angiography in cases of an unsure diagnosis.
- The decision to opt for thrombolysis over surgery depends on risk assessment on an individual patient basis (i.e. risks of surgery vs risks of thrombolysis)
- You should use heparin anticoagulation after both surgery and thrombolysis!
After initial treatment
- Look for a source of emboli – e.g. ultrasounds of aorta, popliteal and femoral arteries for signs of aneurysm
- Watch out for reperfusion injury – which can lead to compartment syndrome
Case Example
- 92 year old nursing home patient
- Painful left leg, sudden onset
- Deaf and dementia
- Comfortable after 5mg morphine (relatively small dose)
- BP 110/40 – probably slightly low
- HR 80 irregular
- RR 16
- Heart sounds normal
- Apyrexic
- Whole left leg is white and cold
- Some mottling from foot to just above knee
- Calf is very tender
- Can barely move right leg, but can wiggle toes. Cannot move left leg at all
- Pulses on the right are normal
- No palpable aortic aneurysm
- No obvious swelling of the leg