Calculating the duration of oxygen flow includes subtraction of which pressure?

The correct choice involves subtracting 200 PSI when calculating the duration of oxygen flow from an oxygen tank. This is because the calculation typically considers the amount of usable oxygen remaining in the tank. The pressure reading on an oxygen tank can vary based on the size and type of tank, but for standard calculations in emergency medical settings, the pressure of 200 PSI is considered the minimum pressure at which oxygen is still effectively usable.

Subtracting this pressure allows for a more accurate determination of how much oxygen is available for patient use. Using a value below this threshold might suggest that there isn’t sufficient oxygen left for practical use, thus impacting the operational efficiency of providing care.

In contrast, the other pressure values mentioned do not represent the standard minimum threshold for usable oxygen, and calculating duration with those values would lead to an incorrect assessment of the tank’s functionality. Thus, recognizing the importance of the 200 PSI benchmark is crucial for paramedics in ensuring they can safely and effectively manage oxygen delivery in the field.