Using a bag-valve-mask without supplemental oxygen delivers approximately what percentage of oxygen?

Using a bag-valve-mask without supplemental oxygen delivers approximately what percentage of oxygen?

• A. 17%
• B. 21%
• C. 50%
• D. 90%

Answer: (B)

A bag-valve-mask by itself does not add oxygen to the gas you deliver. If you aren’t connected to an oxygen source, you’re simply delivering ambient air with its normal oxygen content. Ambient air contains about 21% oxygen (roughly 20.9%), so the inspired oxygen fraction with a BVM used without supplemental oxygen is around 21%. If you connect oxygen and/or use a reservoir, you can increase that substantially, but without supplemental oxygen the value stays near room air.

A bag-valve-mask by itself does not add oxygen to the gas you deliver. If you aren’t connected to an oxygen source, you’re simply delivering ambient air with its normal oxygen content. Ambient air contains about 21% oxygen (roughly 20.9%), so the inspired oxygen fraction with a BVM used without supplemental oxygen is around 21%. If you connect oxygen and/or use a reservoir, you can increase that substantially, but without supplemental oxygen the value stays near room air.