title: Effect of sustained inflation vs. stepwise PEEP strategy at birth on gas exchange and lung mechanics in preterm lambs.
abstract: BACKGROUND
  Sustained inflation (SI) at birth facilitates establishment of functional residual capacity (FRC) in the preterm lung, but the ideal lung recruitment strategy is unclear. We have compared the effect of SI and a stepwise positive end-expiratory pressure (PEEP; SEP) strategy in a preterm model.
  
  
  METHODS
  127 d gestation lambs received either 20-s SI (n = 9) or 2 cmH2O stepwise PEEP increases to 20 cmH2O every 10 inflations, and then decreases to 6 cmH2O (n = 10). Ventilation continued for 70 min, with surfactant administered at 10 min. Alveolar-arterial oxygen gradient (AaDO2), compliance (C(dyn)), end-expiratory thoracic volume (EEVRIP; respiratory inductive plethysmography), and EEV and C(dyn) in the gravity-dependent and nondependent hemithoraces (electrical impedance tomography) were measured throughout. Early mRNA markers of lung injury were analyzed using quantitative real-time PCR.
  
  
  RESULTS
  From 15 min of life, AaDO2 was lower in SEP group (P < 0.005; two-way ANOVA). SEP resulted in higher and more homogeneous C(dyn) (P < 0.0001). Mean (SD) EEVRIP at 5 min was 18 (9) ml/kg and 6 (5) ml/kg following SEP and SI, respectively (P = 0.021; Bonferroni posttest); this difference was due to a greater nondependent hemithorax EEV. There was no difference in markers of lung injury.
  
  
  CONCLUSIONS
  An SEP at birth improved gas exchange, lung mechanics, and EEV, without increasing lung injury, compared to the SI strategy used.
authors.affiliation: 1] Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia [2] Department of Neonatology, The Royal Children's Hospital, Parkville, Australia [3] Neonatal Research, The Royal Women's Hospital, Parkville, Australia [4] Department of Paediatrics, University of Melbourne, Melbourne, Australia.
authors.forename: David G
authors.initials: DG
authors.lastname: Tingay
authors.affiliation: 1] Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia [2] Neonatal Research, The Royal Women's Hospital, Parkville, Australia [3] Department of Paediatrics, University of Melbourne, Melbourne, Australia.
authors.forename: Risha
authors.initials: R
authors.lastname: Bhatia
authors.affiliation: 1] Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia [2] Neonatal Research, The Royal Women's Hospital, Parkville, Australia [3] The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Australia.
authors.forename: Georg M
authors.initials: GM
authors.lastname: Schmölzer
authors.affiliation: The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Australia.
authors.forename: Megan J
authors.initials: MJ
authors.lastname: Wallace
authors.affiliation: The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Australia.
authors.forename: Valerie A
authors.initials: VA
authors.lastname: Zahra
authors.affiliation: 1] Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia [2] Neonatal Research, The Royal Women's Hospital, Parkville, Australia [3] Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Australia.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Davis
mesh_terms: D000305:Adrenal Cortex Hormones / Q000737:chemistry; D000818:Animals; D000831:Animals, Newborn; D005260:Female; D005652:Functional Residual Capacity; D008168:Lung / Q000254:growth & development / Q000473:pathology / Q000502:physiology*; D008297:Male; D010100:Oxygen / Q000737:chemistry; D010991:Plethysmography; D011175:Positive-Pressure Respiration / Q000379:methods*; D011312:Pressure; D011659:Pulmonary Gas Exchange; D011663:Pulmonary Surfactants / Q000032:analysis; D060888:Real-Time Polymerase Chain Reaction; D015656:Respiratory Mechanics; D012756:Sheep; D013997:Time Factors
chemical_list: D000305:Adrenal Cortex Hormones; D011663:Pulmonary Surfactants; D010100:Oxygen