When using nasal cannulae, the maximum oxygen flow rate that should be used is 6 litres/min. Why?

  • Nasal cannulae are only capable of delivering an inspired oxygen concentration between 24% and 40%

  • Forany given flow rate, the inspired oxygen concentration will vary between breaths, as it depends upon the rate and depth of the patient’s breath and the inspiratory flow rate.

  • Higher rates can cause nasal mucosal drying and may lead to epistaxis

  • If oxygen is administered at greater than 40% it should be humidified. You cannot humidify oxygen via nasal cannulae