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13.02.20 Sickle cell anaemia

Problems
  • Acute
    • Vaso-occlusive crisis
    • Acute chest syndrome
    • Stroke
    • Infection
    • Anaemia
    • Priapasm
  • Chronic
    • Haemolysis
    • Renal impairment
    • Retinopathy
    • Pulmonary HTN
    • Avascular necrosis (esp. hip)


Acute chest syndrome

  • Definition
    • Noninfectious vaso-occlusive crisis of the pulmonary vasculature
  • Cause
    • Infection => Inflammation/hypoxia
    • PE
    • Fat embolism
  • Signs/symptoms
    • Cough
    • Excruciating chest pain
    • Fever
    • Hypoxia
    • Chest infiltrates on CXR
  • Management
    • Urgent!
    • Transfusion (mainstay)
      • Exchange
        • 8L exchange in 3hrs reduces HbS from 90% to 30%
      • Top-up
        • Careful of hyperviscosity
    • Analgesia to allow air entry
    • Hydration
    • CPAP/IPPV


Stroke

  • Aetiology
    • Infarct
      • 70%
      • Children / older adults
    • Haemorrhage
      • 30%
      • Young adults
  • Primary prevention
    • Stroke Prevention Trial in Sickle Cell Anemia (STOP) trial
      • High stroke risk if the time-averaged maximum mean velocity (TAMMV) of the middle cerebral or intracranial internal carotid arteries measures >200 cm/s on trans-cranial doppler
    • Preventative transfusion


Infection

  • Spleen auto-infarcts by age 3
    • Prophylactic Penicillin V
  • Salmonella osteomyelitis


Aplastic crisis - Parvovirus B19

  • "Slapped cheeks"
  • Once-only infection => Immunity
  • Causes ~10 days of no RBC production
    • No reticulocytes on blood film
    • Normally fine, but causes aplastic crisis in sickle cell


Priapasm

  • Painful erection for >30 minutes
  • Needs intervention within 4 hrs
    • Can => infertility
  • Management
    • Etilefrine (α and β adrenergic agonist)
    • Penile aspiration


Notes

  • Period can trigger a crisis => Can use COCP
  • HbS gives up oxygen easily => Can have adequate tissue delivery with very low Hb (<9)
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