Passive expiratory flow-volume recordings in immature newborn rabbits. Effect of surfactant replacement on the time constant of the respiratory system.
Immature newborn rabbits with a gestational age of 27 days were paralyzed and kept in body plethysmographs. They were ventilated for 10 min with a tidal volume of approximately 10 ml/kg, with or without previous surfactant treatment via the airways. Tidal volumes and flow were recorded with a pneumotachograph connected to the body plethysmograph, and the expiratory time constant of the respiratory system (trs) was determined from flow-volume diagrams. The values of trs after 10 min were significantly higher in surfactant-treated animals than in controls (50 +/- 7 vs. 23 +/- 4 ms; p less than 0.002), indicating stabilization of the alveoli. There was also a close correlation between trs and the compliance values calculated from tidal volumes and ventilator pressure (r = 0.80; p less than 0.001), as well as between trs and the alveolar volume density in histological lung sections, determined by automated image analysis (r = 0.71; p less than 0.001).
Noack
G
G
Department of Pediatric Anesthesiology, St. Göran's Hospital, Stockholm, Sweden.
Curstedt
T
T
Grossmann
G
G
Nilsson
R
R
Robertson
B
B
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D005865:Gestational Age; D008168:Lung / Q000166:cytology / Q000187:drug effects; D008170:Lung Compliance / Q000187:drug effects; D008176:Lung Volume Measurements; D011663:Pulmonary Surfactants / Q000494:pharmacology*; D011817:Rabbits; D015656:Respiratory Mechanics / Q000187:drug effects*; D013990:Tidal Volume / Q000187:drug effects
D011663:Pulmonary Surfactants