Acute Limb Ischaemia Flashcards
What is acute limb ischemia?
Acute limb ischaemia is defined as the sudden decrease in limb perfusion that threatens the viability of the limb.
What are the 3 main causes of acute limb ischemia?
- Embolisation
- Thrombosis in situ
- Trauma
Briefly describe embolisation in context of acute limb ischemia
Embolisation whereby a thrombus from a proximal source travels distally to occlude the artery (most common).
The original thrombus source may be as a result of AF, post-MI mural-thrombus, abdominal aortic aneurysm or prosthetic heart valves.
Briefly describe thrombosis in context of acute limb ischemia
Thrombosis in situ whereby an atheroma plaque in the artery ruptures and a thrombus forms on the plaque’s cap (presenting as acute or acute-on-chronic).
What are the 6 P’s of acute limb ischemia?
Pain
Pallor
Pulselessness
Paresthesia
Perishingly cold
Paralysis
Give examples of potential causes of embolisation
Causes of potential embolisation should be explored:
- Chronic limb ischaemia
- Atrial fibrillation
- Recent MI (resulting in a mural thrombus)
- Symptomatic AAA (ask about back/abdominal pain)
- Peripheral aneurysms
Describe category I from Clinical Categories of Acute Limb Ischemia
Note: prognosis, sensory loss, motor deficit, arterial and venous doppler
Describe category II from Clinical Categories of Acute Limb Ischemia
Note: prognosis, sensory loss, motor deficit, arterial and venous doppler
Describe category III from Clinical Categories of Acute Limb Ischemia
Note: prognosis, sensory loss, motor deficit, arterial and venous doppler
Describe category IV from Clinical Categories of Acute Limb Ischemia
Note: prognosis, sensory loss, motor deficit, arterial and venous doppler
What differentials should be considered for acute limb ischemia?
The differential diagnoses for acute limb ischaemia include critical chronic limb ischaemia, acute DVT (can present as Phlegmasia cerulea dolens and Phlegmasia alba dolens), or spinal cord or peripheral nerve compression.
What investigations should be ordered for acute limb ischemia?
Routine bloods, including a serum lactate (to assess the level of ischaemia), a thrombophilia screen (if <50yrs without known risk factors), and a group and save, should be taken, along with an ECG.
Suspected cases should be initially investigated with beside Doppler ultrasound scan (both limbs), followed by considering a CT angiography.
If the limb is considered to be salvageable, a CT arteriogram can provide more information regarding the anatomical location of the occlusion and can help decide the operative approach (such as femoral vs. popliteal incision).
Briefly describe the initial management of acute limb ischemia
Acute limb ischaemia is a surgical emergency. Complete arterial occlusion will lead to irreversible tissue damage within 6 hours. Early senior surgical support is vital.
Start the patient on high-flow oxygen and ensure adequate IV access. A therapeutic dose heparin or preferably a bolus dose then heparin infusion should be initiated as soon as is practical.
What is the conservative management of acute limb ischemia?
Conservative management can often be considered those Rutherford 1 and 2a; a prolonged course of heparin may be the most effective non-operative management of acute limb ischaemia.
Any patient started on conservative management via heparin will need regular assessment to determine its effectiveness through monitoring APPT and clinical review. Surgical interventions may be warranted if no significant improvement is seen.
What are the surgical interventions for acute limb ischemia?
Note: embolic
Surgical intervention is mandatory for cases presenting in Rutherford 2b.
If the cause is embolic, the options are:
- Embolectomy via a Fogarty catheter
- Local intra-arterial thrombolysis*
- Bypass surgery (if there is insufficient flow back)
