title: Unilateral acid aspiration augments the effects of ventilator lung injury in the contralateral lung.
abstract: BACKGROUND
  Mechanical ventilation is necessary during acute respiratory distress syndrome, but it promotes lung injury because of the excessive stretch applied to the aerated parenchyma. The authors' hypothesis was that after a regional lung injury, the noxious effect of mechanical ventilation on the remaining aerated parenchyma would be more pronounced.
  
  
  METHODS
  Mice, instilled with hydrochloric acid (HCl) in the right lung, was assigned to one of the following groups: mechanical ventilation with tidal volumes (VT) 25 ml/kg (HCl-VILI25, n = 12), or VT 15 ml/kg (HCl-VILI15, n = 9), or spontaneous breathing (HCl-SB, n = 14). Healthy mice were ventilated with VT 25 ml/kg (VILI25, n = 11). Arterial oxygenation, lung compliance, bronchoalveolar lavage inflammatory cells, albumin, and cytokines concentration were measured.
  
  
  RESULTS
  After 7 h, oxygenation and lung compliance resulted lower in HCl-VILI25 than in VILI25 (P < 0.05, 210 ± 54 vs. 479 ± 83 mmHg, and 32 ± 3.5 vs. 45 ± 4.1 µl/cm H2O, mean ± SD, respectively). After right lung injury, the left lung of HCl-VILI25 group received a greater fraction of the VT than the VILI25 group, despite an identical global VT. The number of total and polymorphonuclear cells in bronchoalveolar lavage resulted significantly higher in HCl-VILI25, compared with the other groups, in not only the right lung, but also in the left lung. The albumin content in the left lung resulted higher in HCl-VILI25 than in VILI25 (224 ± 85 vs. 33 ± 6 µg/ml; P < 0.05). Cytokines levels did not differ between groups.
  
  
  CONCLUSIONS
  Aggressive mechanical ventilation aggravates the preexisting lung injury, which is noxious for the contralateral, not previously injured lung, possibly because of a regional redistribution of VT.
authors.affiliation: Department of Emergency, San Gerardo Hospital, Monza MB, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Amigoni
authors.forename: Giacomo
authors.initials: G
authors.lastname: Bellani
authors.forename: Vanessa
authors.initials: V
authors.lastname: Zambelli
authors.forename: Margherita
authors.initials: M
authors.lastname: Scanziani
authors.forename: Francesca
authors.initials: F
authors.lastname: Farina
authors.forename: Lorella
authors.initials: L
authors.lastname: Fagnani
authors.forename: Roberto
authors.initials: R
authors.lastname: Latini
authors.forename: Roberto
authors.initials: R
authors.lastname: Fumagalli
authors.forename: Antonio
authors.initials: A
authors.lastname: Pesenti
mesh_terms: D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D016207:Cytokines / Q000032:analysis; D006439:Hemodynamics; D008170:Lung Compliance; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011015:Pneumonia, Aspiration / Q000150:complications*; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial; D013990:Tidal Volume; D055397:Ventilator-Induced Lung Injury / Q000209:etiology*
chemical_list: D016207:Cytokines