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ABG Interpretation


March 4th, 2023
On this page:Hypoxia


The PaO₂ is the partial pressure of oxygen dissolved in plasma. This is a marker of the amount of oxygen available to be delivered to tissues, and a reduced PaO₂ is indicative of hypoxia.
    • Normal Range

    • 80-100mmHg on room air


  • Causes of Hypoxia

  • Low Partial Pressure of O₂

  • High altitude
  • Hypoventilation

  • CNS - drugs, trauma, encephalopathy, MND, Guillain-Barré
  • Muscular / neuromuscular - myaesthenia, paralytics, myopathy, fatigue, malnutrition
  • Airway obstruction
  • Decreased compliance
  • Chest wall abnormalities
  • V/Q Mismatch

  • Physiological shunt - atelectasis, pulmonary oedema, pneumonia, ARDS
  • Anatomical shunt - cardiac shunt e.g. tetralogy of Fallot
  • Dead space - asthma, COPD, pulmonary embolus, heart failure
  • Decreased Diffusion Capacity

  • Rare
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