Certified Respiratory Therapist Practice Exam

What factor should be calculated to determine the duration of flow for an oxygen cylinder?

1. Patient's oxygen requirement

2. The cylinder factor and pressure

3. Volume of contents in liters

4. Type of gas being delivered

The correct answer is: The cylinder factor and pressure

To determine the duration of flow for an oxygen cylinder, the calculation involves the cylinder factor and the pressure remaining in the cylinder. The cylinder factor provides a specific volume of oxygen contained in the cylinder at a certain pressure, usually measured in liters per atmosphere (L/atm). By knowing the remaining pressure in the cylinder (measured in psi or atm), you can multiply it by the cylinder factor to find the total available volume of gas. After calculating the total volume, you can divide this by the flow rate being used to determine how long the oxygen will last. This approach ensures that you're accurately considering both the size and remaining contents of the cylinder. In clinical practice, understanding this calculation is essential for planning and ensuring sufficient oxygen delivery during patient care. Other factors, while relevant to patient management, do not directly influence the calculation of duration for the oxygen cylinder. For instance, the patient's oxygen requirement is important for determining flow rate but does not affect the total volume calculation; the volume of contents is already incorporated in the cylinder factor, and the type of gas is less relevant in terms of duration calculation when focusing on oxygen delivery specifically.