title: Positive end-expiratory pressure and tidal volume during initial ventilation of preterm lambs.
abstract: Positive end-expiratory pressure (PEEP) protects the lung from injury during sustained ventilation, but its role in protecting the lung from injury during the initiation of ventilation in the delivery room is not established. We aimed to evaluate whether PEEP and/or tidal volume (VT) within the first 15-min of ventilation are protective against lung injury. Operatively delivered preterm lambs (133 +/- 1 d gestation) were randomly assigned to unventilated controls or to one of four 15 min ventilation interventions: 1) VT15 mL/kg, PEEP 0 cm H2O; 2) VT15 mL/kg, PEEP 5 cm H2O; 3) VT8 mL/kg, PEEP 0 cm H2O; and 4) VT8 mL/kg, PEEP 5 cm H2O. Each group was subsequently ventilated with VT 10 mL/kg, PEEP 5 cm H2O for 1 h 45 min. Lung function was assessed and measurements of lung injury were evaluated postmortem. After the 15 min ventilation maneuver, the VT15 groups were hypocarbic, had higher oxygenation, and required lower pressures than the VT8 groups; no consistent effect of PEEP was found. Markers of lung injury were significantly elevated in all ventilation groups compared with unventilated controls; no effect of PEEP was found. Ventilation resulted in localization of IL-6 to the small airways. Initial ventilation of preterm lambs with PEEP and/or VT of 8 mL/kg did not prevent an inflammatory injury to the lung.
authors.affiliation: School of Women's and Infants' Health, The University of Western Australia, Perth, Western Australia, 6009, Australia. graeme.polglase@uwa.edu.au
authors.forename: Graeme R
authors.initials: GR
authors.lastname: Polglase
authors.forename: Noah H
authors.initials: NH
authors.lastname: Hillman
authors.forename: J Jane
authors.initials: JJ
authors.lastname: Pillow
authors.forename: Fook-Choe
authors.initials: FC
authors.lastname: Cheah
authors.forename: Ilias
authors.initials: I
authors.lastname: Nitsos
authors.forename: Timothy J M
authors.initials: TJ
authors.lastname: Moss
authors.forename: Boris W
authors.initials: BW
authors.lastname: Kramer
authors.forename: Machiko
authors.initials: M
authors.lastname: Ikegami
authors.forename: Suhas G
authors.initials: SG
authors.lastname: Kallapur
authors.forename: Alan H
authors.initials: AH
authors.lastname: Jobe
mesh_terms: D000818:Animals; D005260:Female; D005865:Gestational Age; D008168:Lung / Q000473:pathology / Q000503:physiopathology*; D055370:Lung Injury / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D011175:Positive-Pressure Respiration; D011247:Pregnancy; D047928:Premature Birth; D012123:Pulmonary Ventilation; D012756:Sheep; D013990:Tidal Volume; D013997:Time Factors