What is the percentage of oxygen delivered by a nasal cannula at 4 lpm?

When using a nasal cannula, the percentage of oxygen delivered can be estimated based on the flow rate. For a nasal cannula, it is generally accepted that for every liter per minute of oxygen flow, the percentage of oxygen delivered increases by approximately 4% starting from a baseline of 21%, which is the oxygen concentration in room air.

At a flow rate of 4 liters per minute, the calculation would be:

• Room air = 21%
• Oxygen from the nasal cannula = 4 liters x 4% = 16%
• Total oxygen delivered = 21% + 16% = 37%

However, the typical clinical practice states that at 4 lpm, this is often rounded to around 28%, since it’s a common estimation in emergency services training. In this context, the percentage of oxygen delivered would be more accurately represented as 28%, leading to this choice being considered correct for practical applications in the field.

This is important for first responders to understand as they evaluate the adequacy of oxygenation in patients and determine appropriate interventions.