Preceding surfactant treatment does not protect against lung volutrauma at birth † 1518

Manual ventilation with a few large breaths at birth may cause lung injury in immature lambs. The severity of injury was related to the size of lung inflations (8-32 ml/kg), but even modest inflations before surfactant (S) caused a significant lung function impairment (Pediatr Res 1996;39:326A). We now studied if preceding S treatment would protect the lungs against this injury, and if not, for how long after S the lungs would be sensitive to deep inflations. Twelve lambs of gestational age 127 days were randomized to four different treatments: 1) Five inflations of 16 ml/kg at birth immediately followed by S, 2) S at birth immediately followed by inflations, 3) S at birth, inflations at 10 min, 4) S at birth, inflations at 60 min. Lung mechanics was repeatedly measured during 4 hours of pressure limited mechanical ventilation. Significantly higher airway pressures were generated by inflations at birth (groups 1 and 2) than when inflations were postponed(groups 3 and 4). Static compliance (see figure) and inspiratory capacity remained low throughout the study in groups 1 and 2. We conclude that deep inflations at birth caused lung function impairment whether they were preceded by S or not, but already at 10 min inflations of the same size caused no apparent harm. Ventilation of preterm infants may need to be very tender during the first few minutes of life.