Makindo Medical Notes

Related Subjects: Acute Kidney Injury |Acute Rhabdomyolysis |Hyperkalaemia

Look for the 6 Ps: Pain, Pallor, Pulselessness, Perishing cold, Paraesthesia, and Paralysis. Acute limb ischaemia from an embolus in a previously normal limb is a surgical emergency, often requiring immediate embolectomy without preoperative angiogram.

Initial Management of Acute Limb Ischemia

About

• The limb may be salvageable with prompt surgical intervention.
• Rapid intervention is critical—aim for treatment within 6 hours.

Aetiology

• Embolic Causes: Often sudden onset, usually from:
  • Femoral or popliteal artery embolus
  • Saddle embolism at aortic bifurcation
  • Cardiac emboli due to AF, mural thrombus post-MI, ventricular aneurysm, or endocarditis
• Thrombotic Causes: In situ thrombosis, often in patients with atherosclerosis, with a gradual or staggered onset; may present with an audible bruit.

Clinical Features: The 6 Ps

• Pain: Severe and often disproportionate to physical findings.
• Pallor: Lack of color in the affected limb.
• Pulselessness: Absent distal pulses.
• Perishing cold: Cold extremity with capillary refill >2 seconds.
• Paraesthesia: Loss of sensation.
• Paralysis: Weakness and reduced movement.

Investigations

• Blood Tests: FBC, U&E, LFTs, CK (for rhabdomyolysis), troponin, and clotting profile.
• ECG: Check for AF or recent MI.
• CXR: Evaluate for cardiomegaly, pulmonary edema, or infection.
• Doppler Ultrasound: Check for arterial and venous signals; a normal triphasic arterial waveform is reassuring.
• Group and Crossmatch: Prepare for possible surgery.
• Angiography: May be conducted via femoral artery puncture to confirm diagnosis and assess for intervention options (e.g., angioplasty or stenting in aortoiliac disease). Common risks include haematoma, infection, and contrast-induced nephropathy.

Stages of Acute Limb Ischemia

Management

• Resuscitation: ABCs, high-flow oxygen, IV fluids, and IV heparin (if directed by surgeons). Provide analgesia with slow IV morphine (2.5–5 mg).
• Contact Vascular Surgery: Ensure knowledge of premorbid status, sensory loss, muscle weakness, and compartment tenderness.
• Heparin Protocol: Surgeons may request an IV heparin bolus (usually 5000 units) followed by an infusion adjusted by APTT levels.
• Pre-Operative Planning:
  • Surgeons may proceed directly to the operating room (OR) or request further imaging (e.g., CTA/MRA) based on initial findings.
  • Discuss treatment limitations or goals with the patient and family, especially if comorbidities are present.
• Consider Alkaline Diuresis: If severe rhabdomyolysis is evident (high CK, dark urine).

Surgical and Medical Interventions

• Thrombolysis: Catheter-directed thrombolysis in select cases.
• Embolectomy: Primary treatment for embolic ischaemia; fasciotomy may be required if compartment syndrome is suspected.
• Arterial Bypass: Surgical bypass of obstructed arteries (e.g., aorta to iliac or femoral arteries) in certain cases.
• Amputation: For unsalvageable limbs, consider as a life-saving measure. Palliative care may be considered based on overall prognosis and patient wishes.

Complications

• Hyperkalemia: From tissue necrosis, potentially requiring treatment.
• Compartment Syndrome: May necessitate fasciotomy.
• Systemic Complications: Risk of sepsis, acute renal failure, ARDS, and multi-organ dysfunction in severe cases.