RESPIRATORY SUPPORT, SURFACE-ACTIVITY AND PROTEIN-CONTENT DURING NOSOCOMIAL INFECTION IN PRETERM NEONATES

Small volume bronchoalveolar lavages from 10 infants (26.6 +/- 0.4 wee ks gestational age) during postnatal nosocomial infection were fractio ned by differential centrifugation into large (LA) and small (SA) surf actant aggregates. Before deterioration of the clinical status, the su rface tension at minimum bubble radius (gamma(min)), as measured in a pulsating bubble surfactometer, was reduced to about 14 mN/m by LA and to about 22 mN/m by the corresponding SA. The gamma(min) of both LA a nd SA increased during clinical deterioration, was highest at the wors t clinical state and returned during recovery to values in the range b efore deterioration. Respiratory support significantly correlated to g amma(min) at all times, In contrast, no correlation was observed for t otal protein or albumin content of the LA or SA fractions. The SA frac tion was characterized by a 10-fold higher protein content than LA. Th ese data demonstrate functional impairment of surfactant in subfractio ns during mechanical ventilation and nosocomial infection in preterm n eonates that are not fully explained by inhibition with increasing amo unts of total protein.