Current weight > =1000grams Need for mechanical ventilation Arterial access Signed informed consent by parents/legal guardians The sensor was placed on the abdominal wall and when a routine ABG sample was obtained, the reading from the transcutaneous device was recorded. Photographs were also taken throughout the study to evaluate any injury to the skin from the monitor. The photographs were randomized and a blinded reviewer rated the photographs as normal, mild erythema, or burn/blistering. The reviewer of the photographs confirmed that there were no adverse skin changes. It was concluded that the TCCO2 measurements obtained correlated with the PaCO2 values.