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

We set out to evaluate changes in arterial oxygen tension (PaO 2 ) when weaning neonates from inhaled nitric oxide (INO). We reviewed the records of 505 prospectively collected INO weaning attempts on 84 neonates with hypoxic respiratory failure. PaO 2 values before and 30 min after weaning attempts were recorded. Relationships between change in PaO 2 and decreases in INO concentrations were investigated using regression analysis and ANOVA. PaO 2 decreased (−18.7 ± 1.8 torr; P  < 0.001); when weaning INO. A stepwise decline in PaO 2 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 PaO 2 identified the specific dose reduction 7( P  < 0.001), the prewean PaO 2 ( P  < 0.001), and surfactant therapy ( P  = 0.018) as the variables best describing the change in PaO 2 ( P  = 0.004, r = 0.51). In conclusion, a graded decline in PaO 2 occurs when reducing INO. INO should be weaned to less than 1 ppm before discontinuing its use. Prior surfactant treatment appears to enhance the oxygenation reserve when weaning INO. Pediatr Pulmonol. 2001; 32:14–19. © 2001 Wiley‐Liss,Inc.