title: Positive end-expiratory pressure preserves surfactant function in preterm lambs.
abstract: Ventilation style influences lung injury and the amount of large-aggregate biophysically active surfactant in adult lungs. We asked how positive end-expiratory pressures (PEEP) would influence clinical responses and surfactant pools in surfactant-treated preterm lambs ventilated for 7 h with tidal volumes (VT) of 10 ml/kg. The 126-d gestation preterms were delivered and treated with 100 mg/kg recombinant human surfactant protein C (rSP-C) containing surfactant and ventilated with zero, 4, or 7 cm H(2)O of PEEP. A comparison group was treated with natural sheep surfactant and ventilated with zero PEEP. Physiologic measurements were similar for lambs treated with rSP-C surfactant and natural surfactant. PEEP 4 and 7 improved oxygenation and compliance relative to either group of lambs ventilated with PEEP zero. The maximal lung volumes measured at 40 cm H(2)O pressure after 7 h ventilation for the PEEP 4 and 7 groups were more than double those measured for either PEEP zero group. Alveolar surfactant pools were larger for the PEEP 7 group, and the large-aggregate fraction was increased for the PEEP 4 and 7 groups, resulting in large-aggregate pool sizes that were 3-fold higher for the PEEP 4 and 4-fold higher for the PEEP 7 groups relative to the PEEP zero group treated with rSP-C surfactant. All large-aggregate surfactants lowered minimal surface tensions of a captive bubble to less than 5 mN/m. In preterm surfactant-treated lambs PEEP improved lung function and maintained more of an rSP-C surfactant in the biophysically active form.
authors.affiliation: Division of Pulmonary Biology, Children's Hospital Medical Center, Cincinnati, Ohio, USA.
authors.forename: J
authors.initials: J
authors.lastname: Michna
authors.forename: A H
authors.initials: AH
authors.lastname: Jobe
authors.forename: M
authors.initials: M
authors.lastname: Ikegami
mesh_terms: D000328:Adult; D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008168:Lung / Q000503:physiopathology; D008297:Male; D011175:Positive-Pressure Respiration; D011247:Pregnancy; D011510:Proteolipids / Q000494:pharmacology; D011663:Pulmonary Surfactants / Q000494:pharmacology / Q000502:physiology*; D011994:Recombinant Proteins / Q000494:pharmacology; D012127:Respiratory Distress Syndrome, Newborn / Q000503:physiopathology*; D012756:Sheep; D013990:Tidal Volume / Q000502:physiology; D016896:Treatment Outcome
chemical_list: D011510:Proteolipids; D011663:Pulmonary Surfactants; D011994:Recombinant Proteins; D002245:Carbon Dioxide