What is the maximum safe oxygen flow rate for a simple face mask for an adult?

What is the maximum safe oxygen flow rate for a simple face mask for an adult?

• A. 3-4 L/min
• B. 5-6 L/min
• C. 8-10 L/min
• D. 12-15 L/min

Answer: (B)

A simple face mask delivers oxygen by mixing it with surrounding room air, so the amount of oxygen the patient actually receives depends on how much flow is sent through the mask and how well the mask fits. It’s important to keep the reservoir area partially inflated to minimize rebreathing of carbon dioxide, which happens if the flow isn’t high enough. About 5–6 liters per minute is the commonly used upper range for adults because this flow is high enough to deliver a meaningful oxygen concentration while not being so strong that it causes discomfort, excessive drying, or poor tolerance. Going higher than this doesn’t reliably raise the oxygen concentration much more with a simple mask, due to dilution from room air and mask leakage. If a higher FiO2 is needed, a different device designed for high oxygen delivery should be used.

A simple face mask delivers oxygen by mixing it with surrounding room air, so the amount of oxygen the patient actually receives depends on how much flow is sent through the mask and how well the mask fits. It’s important to keep the reservoir area partially inflated to minimize rebreathing of carbon dioxide, which happens if the flow isn’t high enough. About 5–6 liters per minute is the commonly used upper range for adults because this flow is high enough to deliver a meaningful oxygen concentration while not being so strong that it causes discomfort, excessive drying, or poor tolerance. Going higher than this doesn’t reliably raise the oxygen concentration much more with a simple mask, due to dilution from room air and mask leakage. If a higher FiO2 is needed, a different device designed for high oxygen delivery should be used.