title: High-frequency oscillatory ventilation reduces lung inflammation: a large-animal 24-h model of respiratory distress.
abstract: OBJECTIVE
  High-frequency oscillatory ventilation (HFOV) may reduce ventilator-induced lung injury in experimental neonatal respiratory distress. However, these data permit no conclusions for large animals or adult patients with acute respiratory distress syndrome (ARDS), because in neonates higher frequencies and lower amplitudes can be used, resulting in lower tidal volumes (VT) and airway pressures. The aim of this study was to compare gas exchange, lung histopathology and inflammatory cytokine expression during lung-protective pressure-controlled ventilation (PCV) and HFOV in a long-term large-animal model of ARDS.
  
  
  METHODS
  Prospective, randomized, controlled pilot study.
  
  
  METHODS
  University animal laboratory.
  
  
  METHODS
  Sixteen female pigs (55.3 +/- 3.9 kg).
  
  
  METHODS
  After induction of ARDS by repeated lavage, the animals were randomly assigned to PCV (VT = 6 ml/kg) and HFOV (6 Hz). After lung injury, a standardised lung recruitment was performed in both groups, and ventilation was continued for 24 h.
  
  
  RESULTS
  After lung recruitment sustained improvements in the oxygenation index were observed in both groups. The mean airway pressure (mPaw) was significantly lower in the HFOV group during the experiment (p < 0.01). Histologically, lung inflammation was significantly ameliorated in the HFOV group (p < 0.05). The messenger RNA expression of IL-1-beta in lung tissue was significantly lower in the HFOV-treated animals (p < 0.01).
  
  
  CONCLUSIONS
  These data suggest that HFOV compared with conventional lung-protective ventilation can reduce lung inflammation in a large-animal 24-h model of ARDS. Furthermore, it was shown that lung recruitment leads to sustained improvements in gas exchange with a significantly lower mPaw when HFOV is used.
authors.affiliation: Department of Anaesthesiology, University of Wuerzburg, Oberduerrbacher Strasse 6, 97080 Wuerzburg, Germany. muellenbac_r@klinik.uni-wuerzburg.de
authors.forename: Ralf M
authors.initials: RM
authors.lastname: Muellenbach
authors.forename: Markus
authors.initials: M
authors.lastname: Kredel
authors.forename: Harun M
authors.initials: HM
authors.lastname: Said
authors.forename: Bernd
authors.initials: B
authors.lastname: Klosterhalfen
authors.forename: Bernd
authors.initials: B
authors.lastname: Zollhoefer
authors.forename: Christian
authors.initials: C
authors.lastname: Wunder
authors.forename: Andreas
authors.initials: A
authors.lastname: Redel
authors.forename: Michael
authors.initials: M
authors.lastname: Schmidt
authors.forename: Norbert
authors.initials: N
authors.lastname: Roewer
authors.forename: Jörg
authors.initials: J
authors.lastname: Brederlau
mesh_terms: D000818:Animals; D017931:DNA Primers; D004195:Disease Models, Animal; D005260:Female; D005858:Germany; D006439:Hemodynamics; D006612:High-Frequency Ventilation; D011014:Pneumonia / Q000517:prevention & control*; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange / Q000502:physiology; D011897:Random Allocation; D012128:Respiratory Distress Syndrome / Q000503:physiopathology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine
chemical_list: D017931:DNA Primers