Acute Limb Ischaemia

Scenario

A 68-year old gentlemen presents to A+E with a 6-hour history of severe right sided leg pain. A+E doctors state on examination his right leg appeared pale and cool to the touch, with diminished pulses. He has a past medical history of previous CABG and atrial fibrillation. He is an ex-smoker with a high BMI at 35.

How would you assess this patient?

Upon receiving the call to assess the patient, I would take the following steps in an ABCDE approach and CCrISP triple assessment.

Airway

• Assess the patient's airway to ensure it's patent and not compromised. In this case, unless there are specific indications of airway compromise, it's likely not the primary concern.

Breathing

• Assess the patient's breathing, ensuring they are adequately oxygenating. Given the symptoms described, respiratory distress is less likely, but still should be evaluated.

Circulation

• This is where the primary concern likely lies, given the symptoms of severe right-sided leg pain, pallor, coolness, and diminished pulses.

• Focused Cardiovascular examination:

  • Vital signs: Check blood pressure, heart rate, respiratory rate, and oxygen saturation.

  • Fluid status: Assess for signs of hypovolemia or fluid overload.

  • Peripheral perfusion: Evaluate the peripheral circulation to the extremities.

  • Capillary refill: Check capillary refill time, which may be prolonged in cases of poor perfusion.

• IV Access via 2-large bore cannulas

• Bloods: FBC, U+Es, LFTs, CRP, Lactate, CK, D-dimer

• 12 Lead ECG - ensure not in AF / silent MI

Disability

• Assess the patient's neurological status.

  • Given the presentation, focus on whether there are any neurological deficits in the affected limb.

  • This could include assessing for sensation, strength, and movement.

• GCS, AVPU, Temperature, Glucose

Exposure

• Full neurovascular assessment of both lower limbs

• ABPI / doppler of distal vessels

• PNS examination of lower limb and spine

What would be your primary differential to exclude in this patient?

Given the patient's history of previous CABG, atrial fibrillation, and the acute onset of severe right-sided leg pain with associated signs of peripheral ischemia, the primary concern is likely acute limb ischemia.

This could be due to embolism or thrombosis, especially considering his past medical history and risk factors such as smoking and high BMI.

What are your other potential differential diagnoses?

• Chronic limb ischaemia (e.g. artherosclerosis)

• Spinal pathology

  • Acute spinal cord compression

  • Infarction of spinal cord

• DVT

• Traumatic vascular injury

• Arterial dissection

What questions would you want to know from the patient when taking a focused history?

HPC

• Onset and duration of symptoms

• Recent trauma?

• Previous history of leg claudication or pain

  • Inquire about the distance of claudication

• Presence of contralateral limb symptoms

• Any associated neurological symptoms

• Specifically, ask about weakness and sensory deficits

  
  
  
  

Past medical history

• History of atrial fibrillation (AF)

• History of back pain

• History of peripheral vascular disease

Drug history

• Use of any anticoagulant medication

Specifically how would you examine the limb for potential acute limb ischaemia?

To examine a limb for potential acute limb ischemia, a comprehensive approach encompassing neurovascular examination is crucial:

Vascular Examination

Inspection

• Look for signs of Peripheral Vascular Disease; such as loss of hair, pallor, or arterial ulceration.

• Note the colour of the limb: Is it white, mottled, or bluish/black?

• Examine the toes for signs of cyanosis or necrosis.

Palpation

• Assess radial pulse and heart sounds. Comment on the rate and rhythm; irregularities may indicate AF.

• Evaluate for the presence of an aortic aneurysm, especially if of embolic origin.

• Palpate distal pulses:

  • Femoral

  • Popliteal

  • Dorsalis pedis (DP)

  • Posterior tibial (PT).

• Check CRT at the toes.

• Assess for cold peripheries.

Neurological Examination

Sensory

• Test dermatomes for any sensory deficits.

• Inquire about paraesthesia (abnormal sensations).

Motor

• Assess for paralysis or weakness.

Bedside Investigations

• Doppler: Utilise a bedside doppler to listen for audible triphasic flow, indicating adequate arterial perfusion.

• ECG: Consider an ECG to assess for AF, which can predispose to embolic events.

Note: Paraesthesia or weakness may indicate acute limb ischemia or an alternative diagnosis like spinal cord pathology. It's crucial to discern between these possibilities.

If pulses are difficult to palpate, a handheld doppler can aid in detecting blood flow through these vessels.

What are the 6 Ps of acute limb ischaemia?

P          Pain

P          Paraesthesia

P          Pallor

P          Perishingly cold

P          Pulselessness

P          Paralysis

What are the causes of acute limb ischaemia? Which is most common?

-        Thrombosis (60%)

-        Embolism (30%)

-        Dissection

-        Trauma

What is the difference in presence between embolic and thrombus in-situ in terms of presentation?

This patient has atrial fibrillation on their ECG with no prior history of claudication and a sudden onset of pain 6 hours ago. What is the likely cause and how would you manage this patient?

• This patient likely has an embolism causing acute limb ischaemia. Given their acute onset and atrial fibrillation on the ECG.

• The patient should be urgently discussed with vascular surgeons for consideration of

• embolectomy

What are peri-operative considerations should be considered in a patient with acute limb ischaemia with embolectomy being performed?

High risk of reperfusion injury

• Accumulation of inflammatory and oxidative metabolites leading to tissue damage

• Can lead to:

• SIRS

• Hypotension

• Arrythmias

• Organ dysfunction (e.g. AKI)

Consider Prophylactic Fasciotomies

• The reperfusion injury can lead to tissue swelling

• May lead to post-operative compartment syndrome

• Prophylactic fasciotomies may be performed at initial surgery as there is a strong chance this may occur

Anti-coagulation Considerations

• IV heparin: given peri-operatively (high thrombotic risk – intimal damage etc.)

• Warfarin / DOACs: for long term anticoagulation

What are the potential sources of emboli?

• Atrial fibrillation: Accounts for 80% of embolic causes

• Mural thrombus

• Atherosclerotic plague debris

• Abdominal aortic aneurysm

• Popliteal aneurysm

• Infective emboli: E.g. infected heart valves

Note: Emboli tend to become lodged at arterial bifurcations e.g. popliteal trifurcation.

How is the treatment of thrombus-in-situ managed differently?

?Angiography

• In thrombosis depending on presentation may consider urgent angiography prior to treatment to define the extent and level of occlusion (Category I or IIa ischaemia)

Management

• Consists of either catheter directed thrombolysis / bypass grafting

• This decision would depend on extent of the disease and be guided by the vascular surgery team

Images