Changes in arterial oxygen tension when weaning neonates from inhaled nitric oxide

We set out to evaluate changes in arterial oxygen tension (PaO2) when weani ng neonates from inhaled nitric oxide (INO). We reviewed the records of 505 prospectively collected INO weaning attempts on 84 neonates with hypoxic r espiratory failure. PaO2 values before and 30 min after weaning attempts we re recorded. Relationships between change in PaO2 and decreases in INO conc entrations were investigated using regression analysis and ANOVA. PaO2 decreased (-18.7 +/- 1.8 torr; P < 0.001) when weaning INO. A stepwise decline in PaO2 was observed weaning INO from 40 ppm. The greatest decline occurred when INO was discontinued (-42.1 +/- 4.1 torr). Forward: stepwise multiple regression using variables with significant relationships to the decline in PaO2 identified the specific dose reduction (P <0.001), the prew ean PaO2 (P < 0.001), and surfactant therapy (P = 0.018) as the variables b est describing the change in PaO2 (P = 0.004, r = 0.51). In conclusion, a graded decline in PaO2 occurs when reducing INO. INO shoul d be weaned to less than 1 ppm before discontinuing its use. Prior surfacta nt treatment appears to enhance the oxygenation reserve when weaning INO. P ublished 2001 Wiley-Liss, Inc.