Surfactant aerosol treatment of respiratory distress syndrome in the spontaneously breathing premature rabbit.

Surfactant deficiency in premature neonates is a major factor in the development of respiratory distress syndrome (RDS), which is still a significant cause of mortality and morbidity. The aim of this study was to test a noninvasive method of administering surfactant as treatment for RDS. The animal model used was the premature neonatal rabbit of 27-d gestation (full-term being 31 d) primed with an initial oropharyngeal dose of surfactant. The animals were divided into three groups that received either no supplemental surfactant (n = 20), undried nebulized surfactant (n = 21), or dried nebulized surfactant (n = 24). Drying of the surfactant solution was undertaken to create a hygroscopic aerosol that would facilitate surfactant deposition in the lower respiratory tract. The group treated with dried surfactant aerosol showed superior survival (66.7%) and less evidence of RDS. The control and undried aerosol groups each had similar low survival rates (23.8 and 45.0%, respectively). The results indicate that a dried, hygroscopic aerosol is an effective means of administration of surfactant to spontaneously breathing premature rabbit neonates.

The effect of positive end expiratory pressure on rebreathing and gas dilution in the Ayre's T-piece system--a laboratory study.

The effect of positive end expiratory pressure on the function of the Ayre's T-Piece System was studied using a simple lung model. Positive end expiratory pressure did not effect end tial CO2 during "controlled breathing" but caused an increase during "spontaneous breathing" when fresh gas flow was less than 3 times the minute volume. Gas dilution did not occur under any of the test conditions.