How often should a transcutaneous (TC) sensor be replaced?

• A. 1-2 hours
• B. 8-12 hours
• C. 24 hours
• D. 4-6 hours

Answer: (D)

Transcutaneous sensors rely on a heated skin patch to estimate arterial CO2 by diffusion from the capillaries, and their accuracy can drift as the sensor ages and the skin site changes. The heating and contact with skin can also cause irritation over time. To keep readings reliable and minimize skin injury, the sensor should be replaced or recalibrated at regular intervals. Four to six hours provides a practical balance between drift, calibration stability, and safety, making this the best routine replacement window. If the patient’s condition changes or readings don’t match clinical findings, check or reposition the sensor sooner and reassess skin integrity.