[Severe neonatal respiratory distress with linear inspiratory pressure-volume curve]

Twenty-four newborns with severe respiratory distress, treated by mechanical ventilation, are investigated by inspiratory pressure-volume curve. The curves are obtained by slow continuous inflation technique. Two shapes are described: concave curve, ten newborns (group I), linear curve, fourteen newborns (group II). The gestational age is over 36 weeks in both groups. Determination of respiratory mechanics is indicated when mean AaDO2 is higher than 500 torr in both groups, and when there is a hypercapnia (PaCO2 = 53 +/- 11 torr, with p less than 0.05) in group II. Mechanical ventilation is conducted with individually adjusted PEEP in group I, and without PEEP in group II. Twelve hours after; mean AaDO2 in group I (260 +/- 101 torr) and in group II (420 +/- 188 torr) are significantly different (p less than 0.05). The variance analysis in group II shows that PaCO2 and pH are normalized (p less than 0.001). All the newborns in group I recovered. Three newborns in group II died. Group I can be assimilated to hyaline membrane disease in full-term neonates. Practically, the cases of neonatal respiratory distress in which PEEP is not indicated can be identified by the functional characteristics of group II.