Oxygen requirements

If the patient is receiving oxygen therapy their PaO2 should be approximately 10kPa less than the % inspired concentration FiO2 (so a patient on 40% oxygen would be expected to have a PaO2 of approximately 30kPa /225mmHg).

• Remember room air has an oxygen concentration of 21% already.
• FiO2 stands for fraction of inspired oxygen (O2). 
• Every litre approximately increases the FiO2 by about 4 percent.

Nasal canula rates:

• 1L / min – 24%
• 2L/ min – 28%
• 3L/ min – 32%
• 4L / min – 36%

Reservoir (non-rebreath) mask

Reservoir masks deliver oxygen at concentrations between 60% and 90% when used at a flow rate of 10–15 l/min.³

Simple face mask:

Simple face masks can deliver a maximum FiO2 of approximately 40%-60% at a flow rate of 15L/min.

Venturi Masks