title: Changes in lung volume and ventilation during lung recruitment in high-frequency ventilated preterm infants with respiratory distress syndrome.
abstract: OBJECTIVE
  To assess global and regional changes in lung volume and ventilation during lung recruitment in preterm infants with respiratory distress syndrome.
  
  
  METHODS
  Using electrical impedance tomography, changes in lung volume and ventilation were measured in 15 high-frequency oscillatory ventilated preterm infants during oxygenation-guided recruitment maneuvers. The inflation and deflation limbs were mapped, and the lower and upper inflection points were calculated using both oxygenation and impedance data. The impedance data were also used to determine recruitment-related changes in oscillation volume and distribution.
  
  
  RESULTS
  During inflation, lower and upper inflection points were identified in the majority of infants. The deflation limb showed clear lung hysteresis in all infants. The upper inflection point was significantly lower when comparing the pressure/oxygenation and pressure/impedance curves. Lung volume changes differed between the ventral and dorsal regions, but did not show a consistent pattern. Optimal recruitment increased the oscillation volume, but the distribution of ventilation was relatively homogeneous along the ventral-dorsal axis.
  
  
  CONCLUSIONS
  Lung hysteresis is present in preterm infants with respiratory distress syndrome. Regional differences in lung volume changes and ventilation during high-frequency oscillatory ventilation with lung recruitment are relatively modest and do not follow a gravity-dependent distribution.
authors.affiliation: Department of Neonatology, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands. m.miedema@amc.uva.nl
authors.forename: Martijn
authors.initials: M
authors.lastname: Miedema
authors.forename: Frans H
authors.initials: FH
authors.lastname: de Jongh
authors.forename: Inez
authors.initials: I
authors.lastname: Frerichs
authors.forename: Mariëtte B
authors.initials: MB
authors.lastname: van Veenendaal
authors.forename: Anton H
authors.initials: AH
authors.lastname: van Kaam
mesh_terms: D017097:Electric Impedance; D006612:High-Frequency Ventilation / Q000379:methods*; D006801:Humans; D007231:Infant, Newborn; D008168:Lung / Q000503:physiopathology*; D008176:Lung Volume Measurements / Q000379:methods; D012127:Respiratory Distress Syndrome, Newborn / Q000503:physiopathology / Q000628:therapy*; D014054:Tomography / Q000379:methods*; D016896:Treatment Outcome