The study that uses an adhesive fixation ring on intact skin with electrolyte solution and heats the skin to 44-45°C to cause vasodilation is called what test?

• A. Photoplethysmography
• B. Volume plethysmography
• C. Impedance plethysmography
• D. tcPO2

Answer: (D)

Transcutaneous oxygen pressure measurement uses an adhesive sensor ring placed on intact skin with an electrolyte medium and heated to about 44–45°C. That controlled heating causes vasodilation, increasing cutaneous blood flow so that arterialized blood reaches the capillaries beneath the sensor. The electrode then measures the oxygen tension in that tissue, giving a noninvasive estimate of tissue oxygenation and perfusion that’s useful for evaluating wound healing potential and limb ischemia.

Other tests described by the options rely on different principles—optical detection of blood volume changes, volume changes from cuff-based plethysmography, or electrical impedance—without using a heated transcutaneous oxygen sensor.