 4. Blinding procedure for Nitric Oxide and Nitrogen delivery A double-blind study will be performed to avoid potential patient and investigator bias. The participants, and those analyzing data and assessing the outcomes, will be blinded to group assignment. The test gas tank and the gas delivery system in the operating room OR and at the bedside will be masked to keep the investigators and clinicians treating the patient blinded. One perfusionist in the OR and the respiratory therapist in the ICU will be unblinded and will prepare the appropriate test gas tanks and NON2 meters. Blood Met-Hb levels and NONO2 concentrations are safety concerns that the perfusionist and the respiratory therapist will monitor and regulate NO2 levels will be maintained below 2 ppm, and Met-Hb below 5, if necessary by reducing NO concentration to 40 ppm or less according to MGH guidelines NO therapy. 