Which factor can make a transcutaneous oxygen monitor (TCOM) inaccurate?

• A. Hypothermia
• B. Hyperoxia
• C. Normal Perfusion
• D. Elevated Temperature

Answer: (A)

Transcutaneous oxygen monitoring depends on oxygen arriving to the skin tissue and the sensor accurately reading the tissue PO2. The skin is heated by the device to arterialize capillary PO2, but this relies on adequate cutaneous blood flow. When a patient is hypothermic, the blood vessels in the skin constrict, greatly reducing skin perfusion. With less blood delivering oxygen to the measurement site, the tissue PO2 drops and the sensor can give a reading that is falsely low or unstable, making the monitor less accurate.

Hyperoxia would raise the available oxygen but doesn’t inherently make the device unreliable; normal perfusion yields reliable readings; the targeted heating is part of how the device improves accuracy, so elevated temperatures used in its operation don’t typically cause inaccuracy.