Which items should be recorded when taking TC measurements?

• A. Electrode temp, Skin temp, Probe placement, FiO2
• B. Electrode temp only
• C. Skin temp only
• D. Probe placement only

Answer: (A)

Transcutaneous measurements are highly sensitive to several controllable factors, so capturing all of them ensures readings are interpretable and comparable over time. The electrode temperature is set to drive diffusion and sensor response, and recording it lets you know if a reading was influenced by a particular heating level. Skin temperature matters because local perfusion and the diffusion barrier change with temperature; shifts can alter the measured gas tensions. The exact probe placement site is crucial since different body areas vary in perfusion and tissue thickness, which affects accuracy and consistency across measurements. FiO2 is important because the inspired oxygen fraction can influence the gradient driving diffusion and the relationship between transcutaneous readings and true arterial values. Recording all four items provides the necessary context to interpret TC measurements correctly, rather than relying on any single factor alone.