Oxygen Delivery Devices

• Oxygen Delivery Devices - Variable performance devices:

  • Actual oxygen concentration delivered to the patient is variable and dependent on the patient’s breathing pattern
  • Low flow of oxygen which is less than the patient’s peak inspiratory flow rate (PIFR) (PIFR is around 20 L/min but can go up to 25 to 60 L/min)
  • Most air is taken from a flowmeter, remainder of inspired gas is drawn from the surrounding air
  • The higher a patient’s PIFR, the lower the delivered FiO2
  • The delivered FiO2 will vary from minute to minute, and even breath to breath
  • Examples: nasal cannulae and simple facemasks
• Nasal Cannulae:

  • max of 4 l/min of o2, so is a low dosage
• Simple O2 Facemask:

  • provides from 5 to 10 L/min of o2
• Reservoir Masks

  • provides high dosage of o2 of 10 to 15 L/min
• Oxygen Delivery Devices - Reservoir masks:

  • Delivers high amount of FiO2
  • 1 litre reservoir bag
  • Prevent rebreathing with one-way valves
  • Only use with high oxygen flowrates (10 - 15 l/m)
  • Variable performance device
  • Make sure the reservoir bag is not collapsing on inspiration
  • Consider high flow oxygen or Continuous Positive Airways Pressure (CPAP)
• Oxygen Delivery Devices - Fixed performance devices:

  • Always delivers a fixed amount of FiO2
  • Provide a very high flow of premixed gas
  • Delivered oxygen is known, constant and independent of the patient’s breathing pattern
  • Work on the Venturi principle
  • Example: Venturi masks
• Oxygen Delivery Devices - Fixed performance devices:

  • Need a minimum flowrate of oxygen (depicted on mask)
  • Can increase flowrate if patient is breathless
  • Indications:
  • controlled oxygen therapy (chronic hypercapnia)
  • breathless patients (RR > 30 bpm)
  • exercise on O2
• • venturi masks are fixed performance devices
  • simple o2 facemasks, reservoir masks and nasal cannula are variable performance devices