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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%.

  • For any given flow rate, the inspired oxygen concentration will vary between breaths, as it depends upon the rate and depth of the patients 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