Effect of changes in inspired oxygen tension on indexes of oxygenation in ventilated neonates

Several indexes are used to quantify the severity of hypoxemia, including the arterial to alveolar oxygen ratio (a/APO(2)), the alveolar-arterial difference P(a-a)o(2), the ratio Pao(2)/Fio(2), and the oxygenation index (OI = mean airway pressure x Pao(2)/Fio(2)). This study was carried out to test how stable these indexes are when small changes in Fio(2) are made in ventilated neonates.