CHANGES IN ALVEOLAR-ARTERIAL OXYGEN DIFFERENCE AND OXYGENATION INDEX DURING LOW-DOSE NITRIC-OXIDE INHALATION IN 15 NEWBORNS WITH SEVERE RESPIRATORY INSUFFICIENCY

We evaluated changes in alveolar-arterial oxygen differences (AaDO(2)) and oxygenation index (OI) during inhalation of low-dose nitric oxide (INO) in 15 newborns with severe respiratory insufficiency: congenita l diaphragmatic hernia (CDH) -6, asphyxial lung disease -4, meconium a spiration syndrome (MAS) -2, respiratory distress syndrome -2, persist ent pulmonary hypertension of newborn -1. Their mean birth weight was 2522 g (1030-3200 g, SD +/- 575), mean gestational age 36 weeks (29-39 weeks, SD +/- 3.2), mean initial AaDO(2) = 607 mm Hg (574-628 mmHg, S D +/- 14) and mean initial OI = 32 (6-57, SD +/- 12). INO was performe d using the Pulmonox system (Messer Griesheim, Austria) at conventiona l regimens of mechanical ventilation. The initial value of 20 ppm nitr ic oxide (NO) was decreased 6 h later, first to 15 ppm and then, as qu ickly as possible, to 3 ppm. The mean inhalation period was 51 h (6-13 1 h, SD +/- 42). The initial values of AaDO and OI decreased significa ntly within the first 6 h of INO (P < 0.001). After the first 6 h, 4 p atients died: 1 with MAS of an extrapulmonary cause and 3 CDH patients because of pulmonary hypoplasia. In the remaining 11 patients the dec rease in AaDO(2) and OI during the first 24 h of INO was highly signif icant (P < 0.0001). Conclusion In a heterogeneous group of 15 newborns with severe respiratory insufficiency, the initial AaDO(2) and OI dec reased significantly within the first 6 h of INO.