Surfactant increases the uniformity of lung aeration at birth in ventilated preterm rabbits

Pediatr Res. 2011 Jul;70(1):50-5. doi: 10.1203/PDR.0b013e31821be094.


Surfactant deficiency is a major cause of respiratory failure in newborns. We have investigated the roles of surfactant and positive end-expiratory pressure (PEEP) in the development of a functional residual capacity (FRC) and the distribution of ventilation at birth. Preterm rabbit pups (28 d GA) were delivered and received either saline or surfactant and then ventilated with (3PEEP) or without (0PEEP) 3 cm H2O PEEP (groups: saline/0PEEP, surfactant/0PEEP, saline/3PEEP, surfactant/3PEEP). Lung gas volumes were measured using plethysmography, and the uniformity of ventilation was analyzed using phase contrast (PC) x-ray imaging. Surfactant/0PEEP pups had greater FRCs and the lungs were more uniformly ventilated than saline/0PEEP pups; FRC at inflation 19-21 was 2.46 ± 0.52 mL/kg versus 0.91 ± 0.95 mL/kg (p < 0.05). Saline/3PEEP pups developed an FRC of 7.54 ± 1.68 mL/kg at inflation 19-21 (p < 0.05), but the distribution of ventilation was initially nonuniform. Surfactant/3PEEP pups had an FRC of 8.50 ± 0.80 mL/kg (at inflation 19-21), and the distribution of ventilation was more uniform than with saline/3PEEP (p < 0.05). In ventilated preterm newborn rabbits, PEEP has a greater effect on FRC than surfactant, although the two are additive. Surfactant, administered at birth, markedly improved the uniformity of ventilation irrespective of whether PEEP was applied.

Publication types

  • Research Support, Non-U.S. Gov't
  • Video-Audio Media

MeSH terms

  • Animals
  • Animals, Newborn
  • Biological Products / pharmacology*
  • Functional Residual Capacity / drug effects
  • Gestational Age
  • Lung / diagnostic imaging
  • Lung / drug effects*
  • Lung Compliance / drug effects
  • Phospholipids / pharmacology*
  • Plethysmography
  • Positive-Pressure Respiration*
  • Premature Birth*
  • Pulmonary Surfactants / pharmacology*
  • Pulmonary Ventilation / drug effects*
  • Rabbits
  • Radiography
  • Respiratory Mechanics / drug effects


  • Biological Products
  • Phospholipids
  • Pulmonary Surfactants
  • poractant alfa