title: Intermittent alveolar overdistension for 30 or 240 minutes does not produce acute lung injury in normal pig lung.
abstract: BACKGROUND
  The objective is to study whether alveolar overdistension can induce acute lung injury in pigs as assessed by analysis of respiratory and histological parameters and inflammatory markers.
  
  
  METHODS
  Experimental study, using mixed-breed pigs. Animals were assigned to one of the following groups: Control Group (CG) (n = 5), applying mechanical ventilation with tidal volume (Vt) of 10 ml/kg, respiratory rate (RR) of 18 bpm, and FiO2 of 1 for 240 min; High Vt for 30 min (HVt-30) Group (n = 5), applying ventilation with Vt of 50 ml/kg and RR of 8 bpm and FiO2 of 1 for 30 min, followed by ventilation as in the CG for a further 210 min; and HVt-240 Group (n = 5), applying ventilation with Vt of 50 ml/kg, RR of 8 bpm, and FiO2 of 1 for 240 min. Hemodynamic parameters, airway pressures, arterial blood gases, extravascular lung water (EVLW), and cytokines (IL-2, IL-4, IL-6, IL-10, TNF-alpha, and ITF-gamma) in plasma and bronchoalveolar lavage (BAL) were determined. Lungs were fixed with 10% formalin for histological analysis. Results are expressed as mean +/- standard deviation. The ANOVA test was used to compare measurements among the three groups.
  
  
  RESULTS
  At 30 min, airway pressures and oxygenation of HVt-30 and HVt-240 groups were higher than those of controls [Pplateau: 39.2 +/- 5.6 and 33.0+/- 5.1 versus 12.2 +/- 1.3 (P < 0.01); PaO2/FiO2: 443.8 +/- 55 and 430.6 +/- 34 versus 194.4 +/- 77 (P < 0.01)]. In HVt-240 group, these parameters were also higher than in the other two groups at the subsequent measurement times. There were no differences among the groups in EVLW values. Cytokines were undetected or negligible in plasma and BAL in all of the groups. The histological analysis showed no changes suggestive of acute lung injury.
  
  
  CONCLUSIONS
  In this animal model, ventilation for 4 h with large tidal volume did not cause ventilator-induced lung injury.
authors.affiliation: Department of Emergency and Critical Care, Universitary Hospital Virgen de las Nieves, Granada, Spain. mjgardel@telefonica.net
authors.forename: Manuel
authors.initials: M
authors.lastname: García-Delgado
authors.forename: Inés
authors.initials: I
authors.lastname: Navarrete-Sánchez
authors.forename: Manuel
authors.initials: M
authors.lastname: Colmenero
authors.forename: Angel
authors.initials: A
authors.lastname: Touma-Fernández
authors.forename: Javier Esquivias
authors.initials: JE
authors.lastname: López-Cuervo
authors.forename: Laila
authors.initials: L
authors.lastname: Hassan-Montero
authors.forename: Enrique
authors.initials: E
authors.lastname: Fernández-Mondéjar
mesh_terms: D000208:Acute Disease; D000818:Animals; D016207:Cytokines / Q000032:analysis; D004195:Disease Models, Animal; D006439:Hemodynamics; D007249:Inflammation; D011650:Pulmonary Alveoli / Q000473:pathology*; D015203:Reproducibility of Results; D012121:Respiration, Artificial / Q000009:adverse effects*; D013552:Swine; D013990:Tidal Volume; D013997:Time Factors
chemical_list: D016207:Cytokines