Journal of Applied Physiology, Vol 53, Issue 4 838-843, Copyright © 1982 by American Physiological Society
Lung expansion and survival in rabbit neonates treated with surfactant extract
I. L. Metcalfe, R. Pototschnik, R. Burgoyne and G. Enhorning
Preterm rabbit fetuses, delivered on the 27th day of gestation, were
studied following upper airway instillation with either natural surfactant
(NSA) obtained from the lavage of adult rabbit lungs or with a protein-free
suspension of lipids extracted from lung wash (ESA). First, lung compliance
was studied postmortem. The administration of 25 microliters of either
preparation resulted in greater hysteresis (P less than 0.05) than was
observed in control fetuses receiving no surfactant material. Increasing
the phospholipid concentration stepwise from 10 to 50 mg/ml improved airway
expansion and stability. No further improvement was encountered with
concentrations greater than 50 mg/ml. There was no significant difference
in compliance response between NSA and ESA. Morphometry of the lungs also
indicated that the two preparations had an equal effect on compliance.
Second, it was determined how neonatal survival was affected by a
pharyngeal deposition, prior to the first breath, of 50 microliters NSA or
ESA. Both treatment groups demonstrated improved survival (P less than
0.001) when compared with controls receiving no pharyngeal deposition.
These findings offer further support to the concept that protein is not
required for the efficacy of a surfactant supplementation. The equivalence
of the two preparations suggests that a sterile suspension of a
protein-free surfactant extract could be used to prevent or treat
respiratory distress in preterm neonates.
