Detailed Description:

This is a prospective, non-randomized, non-blinded comparative study. There will be no changes to the anesthetic or surgical plan to accommodate this study. Patients undergoing anesthesia will be induced per their anesthetic team. Following endotracheal intubation, the patient will be placed on air (FiO2 21%) at 4 liters per minute fresh gas flow. After a minimum of 3 minutes has elapsed, the anesthesia team will obtain an arterial blood sample of approximately 1 mL. This can be obtained from an arterial line if one is planned for the procedure or already in place by accessing the line per standard procedure. If an arterial line is not placed, the arterial sample will be obtained by percutaneous arterial puncture using ultrasound guidance and a 25-gauge blood gas syringe. The patient's SpO2 will be noted using a pulse oximetry probe placed on the right index finger when the arterial sample is drawn, along with the date/time of sample acquisition. Once the sample is drawn, the patient's anesthetic and surgery will proceed as per his anesthesia team. The arterial sample will be immediately delivered to the Nationwide Children's Hospital laboratory for simultaneous ABG and ABG-CoOx analysis to obtain SaO2S and SaO2C, respectively.}}