Optimizing Transcutaneous Carbon Dioxide Measurement Sites on Humans

This study explores the body sites for measuring transcutaneous carbon dioxide (CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>) noninvasively using a miniaturized monitor that employs a technique known as timedomain dual lifetime referencing. Accurate measurement of CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> levels is crucial for patients with respiratory distress who need monitoring in both clinical and home care settings. We tested this novel monitor by calculating ratio values of luminescence light, indicative of CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> levels, at five d ifferent b ody locations: cheek, forearm, forehead, wrist, and fingertip, on f our subjects. We also conducted a repeatability analysis: we tested the sensor on one subject at the fingertip each day for three consecutive days. Our findings show that while all t ested s ites presented reliable data, the forehead and cheek yielded faster settling times, and the forearm, forehead, and wrist produced less variation in readings. The results highlight the significance of c hoosing e ffective sites for accurate transcutaneous CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> monitoring.