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Oxygen Administration

Low Flow Oxygen



  • Low flow oxygen devices deliver an amount of gas that is less than the patient’s total minute ventilation.
  • The oxygen from the circuit is passively mixed with room air as the patient inspires, resulting in a variable FiO2 that depends on many factors including the respiratory rate, tidal volume and whether the patient is breathing through their nose or mouth.

Nasal Prongs

  • Low flow nasal prongs deliver 100% oxygen at a low flow rate, which is then entrained with room air. Nasal prongs are comfortable and allow the patient to eat, however at flow rates higher than 4 L/min can cause drying of the nasal cavity.
  • FlowFiO₂
    1 L/min~0.24
    2 L/min~0.28
    3 L/min~0.32
    4 L/min~0.36

Simple Face Mask

  • A simple face mask, also known as a Hudson mask, allows a larger amount of oxygen to be entrained with room air. As they have no reservoir bag, the maximum FiO2 possible is around 0.60.
  • The flow into a Hudson mask should be at least 5 L/min, to reduce rebreathing of carbon dioxide.
  • FlowFiO₂
    5 L/min~0.36
    6 L/min~0.42
    7 L/min~0.48
    8 L/min~0.54
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