title: Optimizing lung aeration at birth using a sustained inflation and positive pressure ventilation in preterm rabbits.
abstract: A sustained inflation (SI) facilitates lung aeration, but the most effective pressure and duration are unknown. We investigated the effect of gestational age (GA) and airway liquid volume on the required inflation pressure and SI duration.
  
  
  
  Rabbit kittens were delivered at 27, 29, and 30 d gestation, intubated and airway liquid was aspirated. Either no liquid (control) or 30 ml/kg of liquid was returned to the airways. Lung gas volumes were measured by plethysmography and phase-contrast X-ray-imaging. Starting at 22 cmH2O, airway pressure was increased until airflow commenced and pressure was then held constant. The SI was truncated when 20 ml/kg air had entered the lung and ventilation continued with intermittent positive pressure ventilation (iPPV).
  
  
  
  Higher SI pressures and longer durations were required in 27-d kittens compared to 30-d kittens. During iPPV, 27-d kittens needed higher pressures and had lower functional residual capacity (FRC) compared to 30-d kittens. Adding lung liquid increased SI duration, reduced FRC, and increased resistance and pressures during iPPV in 29- and 30-d kittens.
  
  
  
  Immature kittens required higher starting pressures and longer SI durations to achieve a set inflation volume. Larger airway liquid volumes adversely affected lung function during iPPV in older but not young kittens.
authors.affiliation: Division of Neonatology, Department of Pediatrics, Leiden University Medical Center, Leiden, the Netherlands.|The Ritchie Center, Monash institute for Medical Research, Monash University, Victoria, Australia.
authors.forename: Arjan B
authors.initials: AB
authors.lastname: Te Pas
authors.affiliation: School of Physics and Astronomy, Monash University, Victoria, Australia.
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Kitchen
authors.affiliation: School of Physics and Astronomy, Monash University, Victoria, Australia.
authors.forename: Katie
authors.initials: K
authors.lastname: Lee
authors.affiliation: The Ritchie Center, Monash institute for Medical Research, Monash University, Victoria, Australia.
authors.forename: Megan J
authors.initials: MJ
authors.lastname: Wallace
authors.affiliation: Department of Medical Imaging and Radiation Sciences, Monash University, Victoria, Australia.|Department of Mechanical and Aerospace Engineering, Monash University, Victoria, Australia.
authors.forename: Andreas
authors.initials: A
authors.lastname: Fouras
authors.affiliation: Department of Medical Imaging and Radiation Sciences, Monash University, Victoria, Australia.|Department of Medical Imaging, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Lewis
authors.affiliation: Japan Synchrotron Radiation Research Institute, Hyogo, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Yagi
authors.affiliation: Japan Synchrotron Radiation Research Institute, Hyogo, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Uesugi
authors.affiliation: The Ritchie Center, Monash institute for Medical Research, Monash University, Victoria, Australia.
authors.forename: Stuart B
authors.initials: SB
authors.lastname: Hooper
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001724:Birth Weight; D005260:Female; D005652:Functional Residual Capacity; D005865:Gestational Age; D008168:Lung / Q000503:physiopathology*; D010991:Plethysmography; D011175:Positive-Pressure Respiration / Q000379:methods*; D011247:Pregnancy; D011270:Pregnancy, Animal; D011312:Pressure; D011817:Rabbits; D012129:Respiratory Function Tests; D013990:Tidal Volume; D013997:Time Factors