title: Open lung ventilation improves gas exchange and attenuates secondary lung injury in a piglet model of meconium aspiration.
abstract: OBJECTIVE
  Previous studies failed to show clear benefits of high-frequency ventilation compared with conventional positive pressure ventilation (PPV(CON)) in experimental meconium aspiration syndrome. However, none of these studies applied an open lung ventilation strategy (OLC), which aims to reduce intrapulmonary shunt due to alveolar collapse. We hypothesized that, if combined with an open lung strategy, both high-frequency oscillatory ventilation (HFOV(OLC)) and positive pressure ventilation (PPV(OLC)) would improve gas exchange and attenuate ventilator-induced lung injury in experimental meconium aspiration syndrome.
  
  
  METHODS
  Prospective, randomized animal study.
  
  
  METHODS
  Research laboratory of a large university.
  
  
  METHODS
  Forty-two newborn piglets.
  
  
  METHODS
  Thirty minutes after intratracheal meconium instillation, 36 newborn piglets were assigned to one of three ventilation groups-PPV(OLC), HFOV(OLC), or PPV(CON)-and ventilated for 5 hrs. In both OLC groups, collapsed alveoli were actively recruited and thereafter stabilized using the lowest possible airway pressures. During PPV(CON), ventilator settings were adjusted to prevent critical hypoxia (Pao2 <60 torr [8 kPa]). Six animals served as saline controls.
  
  
  RESULTS
  Compared with the PPV(CON) group, arterial oxygenation and lung mechanics were superior in both OLC groups and the saline controls. Analysis of the bronchoalveolar lavage fluid obtained after 5 hrs of ventilation showed increased myeloperoxidase activity in the PPV(CON) group compared with both OLC groups and saline controls. Alveolar protein influx was not different between the groups. Histologic analysis revealed a higher lung injury score in the PPV(CON) group compared with the PPV(OLC) and the HFOV(OLC) groups.
  
  
  CONCLUSIONS
  Application of the OLC during PPV and HFOV is feasible in experimental meconium aspiration syndrome and results in superior oxygenation and less ventilator-induced lung injury compared with PPV(CON).
authors.affiliation: Department of Anesthesiology, Erasmus-MC Faculty Rotterdam, The Netherlands.
authors.forename: Anton H
authors.initials: AH
authors.lastname: van Kaam
authors.forename: Jack J
authors.initials: JJ
authors.lastname: Haitsma
authors.forename: Anne
authors.initials: A
authors.lastname: De Jaegere
authors.forename: Wim M
authors.initials: WM
authors.lastname: van Aalderen
authors.forename: Joke H
authors.initials: JH
authors.lastname: Kok
authors.forename: Burkhard
authors.initials: B
authors.lastname: Lachmann
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D004195:Disease Models, Animal; D006801:Humans; D007231:Infant, Newborn; D008171:Lung Diseases / Q000209:etiology / Q000517:prevention & control*; D008471:Meconium Aspiration Syndrome / Q000503:physiopathology / Q000628:therapy*; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D011897:Random Allocation; D012121:Respiration, Artificial / Q000009:adverse effects* / Q000379:methods; D013552:Swine