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The role of pulmonary surfactant proteins A, B and D in preterm infants ventilated for respiratory distress receiving different surfactant therapies

Presented at the Neonatal Society 2001 Summer Meeting (programme).

Beresford MW, Shaw NJ

Neonatal Unit, Liverpool Women's Hospital, Liverpool L8 7SS, UK

Background: Surfactant proteins (SP) have fundamental actions in surfactant metabolism, function and immunoregulation (1-3). There is no published data regarding SP concentrations using non-bronchoscopic bronchoalveolar lavage (NB-BAL) from infants with respiratory distress syndrome (RDS) and those who subsequently develop chronic lung disease (CLD). No study has explored postnatal changes in SP-B and SP-D or evaluated the effects of different surfactant preparations on lavage SP concentration.

Aims: To investigate bronchoalveolar SP concentrations in BAL fluid from preterm infants ventilated for RDS and randomised to receive either a natural or a synthetic surfactant.

Methods: Standard NB-BAL was performed on infants <30 weeks gestation randomised to receive poractant alfa or pumactant. Samples were collected on a daily basis (first week) and twice weekly thereafter. SP-A, SP-B and SP-D quantification took place using ELISA techniques and comparisons made between outcomes including CLD and death as well as surfactant type. SP levels expressed as concentration per volume of lavage fluid (ng/mL BAL). All results presented here as median (interquartile range).

Results: Median of 262 samples were analysed from 50 infants. Gestational: 27 weeks (26-28); birth weight 882 grams (712-1016); 34 male; 25 received natural (poractant alfa), 25 artificial (pumactant) surfactant.

BAL concentration of all SP rose significantly over the first postnatal week (p=0.04, 0.02 and 0.001 respectively). SP-B levels, but not SP-A or SP-D, were significantly higher over the first 3 days in poractant alfa treated infants (p<0.02). Infants developing CLD by day 28 had significantly lower SP-D levels on day 2 (p=0.035) and day 3 (p=0.041) than those without. SP-A and SP-B concentrations did not differ significantly between these groups over the first 4 days. On day 2, SP-B levels (5 {3-340} vs 350 {107-1,250}, p=0.033*) and SP-D levels (359 {217-526} vs 698 {400-1091}, p=0.04**), but not SP-A levels, were significantly lower in infants dying compared to those surviving

Surfactant protein concentration and mortality:

Conclusion: BAL SP-B and SP-D concentration appear to influence significantly clinical outcome from RDS unlike SP-A, despite its important in-vitro contributions to surfactant metabolism and function.

1. Creuwels LAJM, van Golde LMG, Haagsman HP. Lung 1997;175:1-39
2. Floros J, Kala, P. Annu Rev Physiol. 1998;60:365-384
3. Eggleton P, Reid KBM. Current Opinion Immuology 1999;11:28-33

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