Interneonatal intensive care unit variation in growth rates and feeding practices in healthy moderately premature infants.

BACKGROUND: Variation in care and outcomes of very low birth weight infants (VLBW) in neonatal intensive care units (NICU) has been widely reported in the past decade. Less is known about care provided to healthy premature infants born between 30 and 35 weeks gestational age (GA). We have previously reported inter-NICU variation in discharge (D/C) timing and achievement of maturational milestones in this population. OBJECTIVE: To compare inter-NICU growth outcomes and feeding practices in healthy, moderately premature infants. METHODS: Records of 450 infants, 30 to 35 weeks gestation, without medical or surgical complications, and consecutively discharged from 15 Massachusetts NICUs (nine Level II and six Level III) were reviewed. Final analyses included 382 infants with hospital length of stay >6 days (d). RESULTS: GA at birth and birth weight (BW) were 33.2 weeks (SD 1.2) and 2024 g (389). Mean Z-score decreased 0.67z (0.37) from birth to D/C. Weight loss from birth to 7 d averaged 4.0%. Mean growth velocity from 7 d to D/C was 13.3 g/k/d (5.2) with net growth velocity of 5.5 g/k/d (5.6). Mean net growth velocity ranged from 0.1 to 8.4 g/k/d (p<0.001) among study NICUs. Time of initiation, rate of advancement and caloric density of feedings also varied significantly between NICUs. CONCLUSION: Mean NICU growth velocity of healthy, moderately premature infants did not achieve in utero growth standards. There was significant inter-NICU variation in growth outcomes and feeding practices. Further study is needed to identify practices associated with better growth in this healthy moderately premature infant population.

Effect of exogenous surfactant on the development of surfactant synthesis in premature rabbit lung.

Surfactant replacement is an effective therapy for neonatal respiratory distress syndrome. Full recovery from respiratory distress syndrome requires development of endogenous surfactant synthesis and metabolism. The influence of exogenous surfactant on the development of surfactant synthesis in premature lungs is not known. We hypothesized that different exogenous surfactants have different effects on the development of endogenous surfactant production in the premature lung. We treated organ cultures of d 25 fetal rabbit lung for 3 d with 100 mg/kg body weight of natural rabbit surfactant, Survanta, and Exosurf and measured their effects on the development of surfactant synthesis. Additional experiments tested how these surfactants and Curosurf affected surfactant protein (SP) SP-A, SP-B, and SP-C mRNA expression. Surfactant synthesis was measured as the incorporation of 3H-choline and 14C-glycerol into disaturated phosphatidylcholine recovered from lamellar bodies. Randomized-block ANOVA showed significant differences among treatments for incorporation of both labels (p < 0.01), with natural rabbit surfactant less than control, Survanta greater than control, and Exosurf unchanged. Additional experiments with natural rabbit surfactant alone showed no significant effects in doses up to 1000 mg/kg. Survanta stimulated disaturated phosphatidylcholine synthesis (173 +/- 41% of control; p = 0.01), increased total lamellar body disaturated phosphatidylcholine by 22% (p < 0.05), and increased 14C-disat-PC specific activity by 35% (p < 0.05). The response to Survanta was dose-dependent up to 1000 mg/kg. Survanta did not affect surfactant release. No surfactant altered the expression of mRNA for SP-A, SP-B, or SP-C. We conclude that surfactant replacement therapy can enhance the maturation of surfactant synthesis, but this potential benefit differs with different surfactant preparations.