Acute Limb Ischemia Flashcards by Aboudi el masri

Define Acute Limb Ischemia

It is a vascular emergency where there is a sudden decrease in limb perfusion threatening limb viability. This is typically caused by occlusion via embolism or thrombosis in situ (not part of definition)

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Give 2 examples of valvular disease that can cause acute limb ischemia

Infective endocarditis
rheumatic heart disease

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Are Janeway lesions painless or painful? where are they located?

Painless
Palms or soles of feet

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Are Osler’s Nodes painless or painful? where are they located?

Painful
dorsal aspect and Pulp of fingers and toes (tip of)

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What is this? What is it a sign of?

Osler Nodes
Infective endocarditis = endocarditis

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What is this? What is it a sign of?

Janeway lesions
Infective endocarditis = endocarditis

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How are Roth spots detected?
What is it?

Fundoscopy
It is a bleeding microinfarct or cotton wool spot surrounded by hemorrhage

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What are the stigmata of infective endocarditis

peripheral signs of microembolization: Petechiae (most common), Splinter hemorrhages (rare), Janeway lesions PAINLESS (rare), Osler Nodes PAINFUL (rare)
Roth spots (eyes)
!!!New or changing Murmur: Mitral or Aortic regurgitation!!!
=> arrhythmias
Tachycardia

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What are the causes/RFs of acute limb ischemia?

Embolic: A fib (80%), Recent MI (mural thrombus within ventricle dislodged), Valve disease, Aneurysm, atheroma, Fat embolus

Thrombotic: Pre-existing PAD (atherosclerotic disease), Bypass graft occlusion/Stent graft occlusion (Iatrogenic complication of AAA repair/EVAR)!!, Prothrombotic conditions

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What is the most common cause of a fat embolus

Fracture of large bones typically occurring in high energy RTA or Orthopedic surgery

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Patients with a history of PAD show more gradual symptoms and often take longer before reaching the stage of irreversible ischemia with regards to acute limb ischemia. Why is that?

Patients with chronic PAD would likely build up collaterals as a backup to this chronic illness but cannot happen acutely.

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A patient presents with severe pain in his right big toe. It is blue, soft, and very tender. The patient is diagnosed with acute limb ischemia. What is the most likely cause of this event? (2)

Aneurysm, most commonly AAA, or an atheroma
A blue toe indicates digital ischemia => small emboli => aneurysm or atheroma produce these
Extra points: If a major vessel were to be occluded in a patient with AAA. What would that vessel be?

Popliteal. Both aneurysms are associated with each other. Remember, popliteal aneurysms are typically bilateral.

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What do you see in this image? This is a patient with a background of Long-standing A.fib, 40 pack year smoking history, complaining of sudden right lower limb pain exacerbated on exertion.
How can you tell if this event is acute or chronic?

DSA scan. Digital Subtraction Angiography. This is a continuous X-ray that uses the computer to detect flow.

This X-ray is positioned on the Right knee (idk if its actually) with DSA of the popliteal artery. an abrupt cut off of blood flow at the popliteal bifurcation, rather than tapering seen with chronic disease. This is consistent with a sudden embolic event causing acute limb ischemia

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What are the clinical features of Acute Limb Ischemia
Stating the 2 most important clinical features and why they’re the most important

ALI is part of PAD => 6Ps
Pain
Pallor
Perishing cold
Pulseless
Paresthesia
Paralysis
Last 2 are the most important as they indicate muscle and nerve ischemia with potential for salvage (neurons still giving signs of life)

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A patient presents to the ED with acute pain in their lower limb and you suspect acute limb ischemia. What can you perform at the bedside to quickly check for the degree of muscle death?

Palpation of the calf muscle
Soft + tender = presence of muscle death but is still salvageable with immediate revascularization
Hard/tense + tender = Significant muscle death + irreversible ischemia

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How would you determine limb viability in a patient presenting acute limb ischemia? State the full process. State the management options available for each case

The Rutherford Criteria categorizes ALI based on salvageability. It uses:
1) Exam findings: Sensory loss and pain at rest + Motor weakness (differentiator)
2) Arterial and Venous Doppler (Venous is a differentiator)
Categories I-IIb are salvageable => Immediate revascularization
whereas Category III is not => Amputation or Palliation

What are the types of amputation in ALI (5)?

Digital amputation: partial or full
Transmetatarsal
BKA - Below knee amputation
TKA - Through knee amputation
AKA - Above knee amputation

Which type of amputation would be used in the case of a patient presenting to the ED with 3 gangrenous toes on the right foot?

Transmetatarsal Amputation

Based on the old surgical Dogma for viability of limb in ALI, If untreated, how long since the time of insult will irreversible damage begin to ensue? How long till the limb is no longer viable and all damage is no longer reversible?

Remember these are general rules based of old studies
< 6 hours reversible
6-12 hours partially reversible => Irreversible damage ensues 6 hours
At 12 hours, the limb is no longer viable and all damage is no longer reversible

In the realm of vascular surgery, what is meant by fixed staining?

Hemosiderin Deposits

There is an old surgical Dogma where surgeons can assess the relationship of time elapsed since insult to physical findings to whether the insult is reversible or not. Explain this relationship.

< 6 hours: painful, marble white foot with neurosensory deficit => Reversible
6-12 hours: Mottled appearance, !blanches on digital pressure! => Partially reversible
>12 hours: Fixed staining (Hemosiderin Deposits), !!No blanching on digital pressure!!, Ant. Compartment red and tender => Irreversible => amputation

A patient presents to the ED with extreme pain in his left leg, peripheries cold on palpation, sensorineural loss on his left big toe and no motor weakness. What is your next step?

This appears to be a case of acute limb ischemia and hence an arterial and venous doppler must be conducted to determine the Rutherford Classification of the limb

What is the normal range of aPTT of an individual not on Heparin?
What is the target aPTT range of an individual on Heparin

Normal: 30-40
Heparin: 60-80/60-90

What is the definitive treatment of a patient with Acute limb ischemia and a viable limb with no obvious embolus on CT angiography?

Thrombolysis +/- Angioplasty

What are the contraindications to thrombolysis?

Active internal bleeding Pregnanct Severe bleeding tendency (coagulopathies) Previous GI Hemorrhage Known Intracerebral tumour, aneurysm, or AV malformation Stroke, TIA, or craniotomy within 2 months Vascular or abdominal surgery within 2 weeks Trauma, biopsy, or puncture of a non-compressible vessel within 10 days

How long before CT angio/angiography should Heparin be stopped as in the case of a stroke or Acute limb ischemia? Why is it stopped before?

Heparin must be stopped 4 hours before It is stopped before due to the complication of leaking of contrast giving a blurry picture

What catheter is used to remove emboli in Acute limb ischemia?

Fogarthy Catheter

What is the definitive treatment of a patient with Acute limb ischemia and a viable limb with an obvious embolus on CT angiography?

Urgent Embolectomy +/- Fasciotomy via Fogarthy catheter

Give 3 Contraindications to Heparin administeration

Platelets <100,000 Coagulopathies (VWF, hemophelia) Active bleeding Recent Surgery, trauma, head injury

A patient presents to the ED with extreme pain in his left leg, peripheries cold on palpation, sensorineural loss on his left big toe and no motor weakness. Arterial Doppler is inaudible while venous is audible. What is your full management plan

1) Admit to hospital 2) ABCDE: Send out FBC w/differentials, U&E, CRP, LFTs, and coag profile, ABG 3) NPO for all, NG tube if vomiting, Intubate if GCS 8 or under or if vomiting 4) O2 if in doubt until ABG becomes available (15L 100% O2 via non-rebreather mask) 5) 2x large bore cannulas, IV fluids at 100ml/hr until losses worked out via intake/output chart +/- urinary catheter 6) Type and save, group and hold, Group and cross match 4 units of blood (10 for AAA). If needed give in 1:1:1 aiming for Hb>8 and >10 in CVD 7) Analgesia (Paracetamol, NSAIDS, Morphine/oxynorm/oxycontin) 8) Antiemetics if needed (Ondansetron) 9) Antibiotics: Coamox/pip taz + Gent/Metronidazole 10) DVT prophylaxis (TEDs, Clexane, LMWH) ECG -> A.fib or recent MI CXR !!!Unfractionated Heparin: Check contraindication, Start 5000 IU then 1000 IU/hr, Check aPTT after 4-6 hours, Aim aPTT b/w 60-90!!! Step 2: Definitive Treatment: Patient has a viable limb => we will attempt to identify and clear the insult before commencing with revascularization. Continue IV Heparin until 4 hours before CT angiogram/ Angiography Obvious Embolus: Urgent Embolectomy +/- Fasciotomy via Fogarthy catheter No obvious embolus: Thrombolysis +/- Angioplasty

A patient presents to the ED with extreme pain in his left leg, peripheries cold on palpation, sensorineural loss on his left big toe and motor weakness on the left side. Both arterial and venous doppler's were inaudible. What is your full management plan?

1) Admit to hospital 2) ABCDE: Send out FBC w/differentials, U&E, CRP, LFTs, and coag profile, ABG 3) NPO for all, NG tube if vomiting, Intubate if GCS 8 or under or if vomiting 4) O2 if in doubt until ABG becomes available (15L 100% O2 via non-rebreather mask) 5) 2x large bore cannulas, IV fluids at 100ml/hr until losses worked out via intake/output chart +/- urinary catheter 6) Type and save, group and hold, Group and cross match 4 units of blood (10 for AAA). If needed give in 1:1:1 aiming for Hb>8 and >10 in CVD 7) Analgesia (Paracetamol, NSAIDS, Morphine/oxynorm/oxycontin) 8) Antiemetics if needed (Ondansetron) 9) Antibiotics: Coamox/pip taz + Gent/Metronidazole 10) DVT prophylaxis (TEDs, Clexane, LMWH) ECG -> A.fib or recent MI CXR !!!Unfractionated Heparin: Check contraindication, Start 5000 IU then 1000 IU/hr, Check aPTT after 4-6 hours, Aim aPTT b/w 60-90!!! Step 2: Definitive Treatment: Based on the Rutherford Classification, this is a category III ALI => Irreversible Ischemia Amputation or palliative care are the options to take based on their fitness for surgery

What is reperfusion injury?

Ischemia involves prolonged oxygen deprivation to tissues. Sudden reperfusion leads to oxygen reactive species formation => cellular injury

What are the 3 complications of reperfusion in acute limb ischemia?

Reperfusion injury: reactive oxygen species Rhabdomyolysis Compartment syndrome

Explain the Pathophysiology of Rhabdomyolysis How is it diagnosed? How is it treated?

It is rapid muscle cell death (myolysis) which causes the release of its cellular components into the bloodstream and is diagnosed via significantly raised serum CPK (Creatine phosphokinase) and reduced urine pH. Myoglobin is also released which is nephrotoxic leading to acute tubular necrosis and renal impairment (AKI) which increases serum K+ that can lead to cardiac arrest Tx: IV fluids + Mannitol (diuresis) + Bicarb salt or Citrate (urine alkalization)

What is compartment syndrome? How is it treated?

Bleeding within compartment => increased pressure inside collapsing arteries => limb ischemia 4-compartment decompressive fasciotomy