Using the nasal cannula FiO2 estimation formula FiO2 = 0.21 + 0.04 × flow, what is the FiO2 at 4 L/min?

Study for the Respiratory Therapy Test. Use flashcards and multiple choice questions, featuring hints and explanations. Prepare for your exam successfully!

Multiple Choice

Using the nasal cannula FiO2 estimation formula FiO2 = 0.21 + 0.04 × flow, what is the FiO2 at 4 L/min?

A nasal cannula FiO2 estimate uses FiO2 = 0.21 + 0.04 × (flow in L/min). With a flow of 4 L/min, you multiply 0.04 by 4 to get 0.16, then add the baseline 0.21. So FiO2 = 0.21 + 0.16 = 0.37, which is 37% oxygen. This matches the given answer. The other values would require different flow rates (e.g., around 2.5 L/min for 0.31, about 4.5 L/min for 0.39, or about 5.25 L/min for 0.42), not the 4 L/min used here.

A nasal cannula FiO2 estimate uses FiO2 = 0.21 + 0.04 × (flow in L/min). With a flow of 4 L/min, you multiply 0.04 by 4 to get 0.16, then add the baseline 0.21. So FiO2 = 0.21 + 0.16 = 0.37, which is 37% oxygen. This matches the given answer. The other values would require different flow rates (e.g., around 2.5 L/min for 0.31, about 4.5 L/min for 0.39, or about 5.25 L/min for 0.42), not the 4 L/min used here.

More practice questions