Previous studies have been conducted on transcutaneous monitors in newborns. One such study evaluated the CO-OXSYS Digital Sensor (also known as the V-Sign Digital Sensor) made by SenTec. 25 patients between the ages of 10 months to 79 years of age were studied. Each sensor was placed on the tragus of each patient's ear. An ABG was obtained fifteen minutes after sensor application and TCCO2 measurements were recorded at the same time. ABG samples were analyzed with a Rapidpoint 405 analyzer. A reliable correlation was found between the TCCO2 and the PaCO2 readings (R2-0.61, p=<0.001). It was noted that age and temperature did not affect the accuracy of the CO2 readings. This study concluded that with more sampling, the CO-OXSYS Digital Sensor would be useful in a variety of clinical settings.