What could cause an increase in FIO2 at a tracheostomy collar when testing with a galvanic fuel cell analyzer?

• A. Calibration error in the galvanic fuel cell
• B. Clogged jet orifice in the nebulizer
• C. Too much water in the circuit
• D. Aerosol tubing is too short

Answer: (C)

An increase in FIO2 (fraction of inspired oxygen) at a tracheostomy collar when measuring with a galvanic fuel cell analyzer can indeed be attributed to too much water in the circuit. When there is excessive water in the circuit, it can lead to several issues, including increased resistance to gas flow and potential partial occlusion, which can modify the gas mixture that is being delivered. This alteration in flow dynamics can effectively raise the concentration of oxygen being delivered, resulting in a higher FIO2 reading on the analyzer.

The other potential causes might not directly influence the FIO2 reading in the same manner. Calibration errors in the galvanic fuel cell could lead to inaccurate readings but would not inherently change the actual FIO2 being delivered. A clogged jet orifice in the nebulizer would primarily affect aerosol delivery rather than FIO2 levels since it impacts the amount of humidification and medication delivered without necessarily altering oxygen concentration. Lastly, using aerosol tubing that is too short may restrict the flow; however, while this could create turbulence and affect gas delivery, it doesn't specifically lead to an increase in oxygen concentration as much as simply reducing effective delivery. Thus, the presence of excess water is the most plausible direct contributor to the increase in FIO