Final answer:
The calculation of the air:oxygen ratio to achieve a 60% FiO2 is done using a formula that compares the desired FiO2 with the percentage of oxygen in room air and the amount of pure oxygen added. The correct air:oxygen ratio is closest to 1:1, but slightly less than one liter of air is needed for each liter of oxygen.
Step-by-step explanation:
The student is asking for the calculation of air: oxygen ratio needed to achieve a desired Fraction of Inspired Oxygen (FiO2) of 60%. FiO2 refers to the concentration of oxygen in the air that a person breathes.
To calculate this, we know that room air contains approximately 21% oxygen, and the addition of pure oxygen adjusts this percentage. The FiO2 is the percentage of oxygen the patient is inhaling, which for this example is 60%.
The formula to calculate the air to oxygen ratio when adding pure oxygen to room air (21% O2) to achieve a desired FiO2 is:
Ratio = (FiO2 - Room Air O2) / (100% - FiO2)
Plugging in the values:
Ratio = (60% - 21%) / (100% - 60%)Ratio = 39% / 40%
Ratio = 0.975
Since the ratio of air to oxygen needed is less than 1, it means that for each liter of oxygen added, we would need slightly less than 1 liter of air to achieve the 60% FiO2. The correct answer is closest to a 1:1 ratio, but slightly less air would be needed compared to the volume of oxygen.