A respiratory therapist checks a jet nebulizer with an entrainment setting of 35%, but measures a concentration of 45% with an oxygen analyzer. What is the best explanation for this finding?

The finding of a measured oxygen concentration of 45% when the entrainment setting is set to 35% can be best explained by the presence of water in the tubing. When water accumulates in the nebulizer tubing, it can create a blockage that alters the intended air flow dynamics. This blockage can cause the entrainment of a higher percentage of oxygen than the set level, resulting in a higher measured concentration.

Water in the tubing can disrupt the flow of gases and can potentially create backpressure, which may lead to the system pulling in more oxygen than anticipated. This is particularly significant in systems like jet nebulizers that rely on specific flow characteristics to deliver the desired concentration of aerosolized medication to patients. The higher concentration reading is indicative that the flow dynamics are not performing as designed due to this interference.

Other factors, such as inadequate flow or jet orifice obstructions, could affect the functioning of the nebulizer, but they would typically lead to decreased aerosol output or altered delivery rather than a straightforward increase in oxygen concentration. Excessive flow from the flowmeter could also create changes in the output, but it is less likely to directly cause a higher oxygen concentration measurement than the setting indicates. The presence of water is thus the most plausible explanation for the