Effects of variable concentrations of inhaled nitric oxide and oxygen on the lungs of newborn piglets.

We previously demonstrated that inhalation of high concentrations of nitric oxide (iNO) and oxygen for 48 hr causes significant lung injury in newborn piglets. To determine if these effects persist at lower concentrations, groups of newborn piglets were mechanically ventilated for 48 hr with (study 1) constant O(2) (90-100%) and decreasing iNO (100-2 ppm) or (study 2) constant iNO (50 ppm) and decreasing O(2) (95-30%). Bronchoalveolar lavage (BAL) fluid was assayed for surfactant function, and markers of lung inflammation and physiologic parameters were monitored.