title: Pulmonary stress injury within physiological ranges of airway and vascular pressures.
abstract: OBJECTIVE
  The aim of this study was to assess the respective role of a small elevation in pulmonary capillary pressure, airway pressure, or both on alveolar capillary barrier permeability in an isolated perfused rat lung model.
  
  
  METHODS
  Four groups were studied with low or high airway pressure (LA: 10 mL/kg (tidal volume); HA: 20 mL/kg), low or high pulmonary artery pressure (LP: 9 mm Hg; HP: 12 mm Hg): LALP, HALP, LAHP, and HAHP. The lungs were ventilated and perfused ex vivo for 30 minutes. Quantification of fluorescein isothiocyanate-labeled (FITC) dextran in bronchoalveolar lavage (BAL) fluid and radiolabeled tracers assessed alveolar capillary barrier permeability.
  
  
  RESULTS
  BALF FITC-dextran was similar in the three groups with either one or two low-pressure parameters (LALP, LAHP, HALP), but high amounts were found in the HAHP group (375.2 x 10(-6) mg/mL v, respectively, 21.4, 26.2, and 30 x 10(-6) mg/mL, P = .0001). These results were consistent with the albumin space and extravascular lung water: higher values only in the HAHP group statistically different from the other groups (P < .002). Interalveolar pore examined with scanning electron microscopy showed an increase in diameters between LALP and HAHP (P < .0001).
  
  
  CONCLUSIONS
  We can conclude that elevation of either the pulmonary artery pressure from 8 to 11 mm Hg or the alveolar pressure from 10 to 15 mm Hg alone does not change the permeability of the alveolar capillary membrane; however, there is an additive effect of these pressures.
authors.affiliation: Laboratoire de Recherche en Pathologie Infectieuse, Faculté de Médecine de Lille, France.
authors.forename: B P
authors.initials: BP
authors.lastname: Guery
authors.forename: B P
authors.initials: BP
authors.lastname: DeBoisblanc
authors.forename: P
authors.initials: P
authors.lastname: Fialdes
authors.forename: T G
authors.initials: TG
authors.lastname: Sarphy
authors.forename: S
authors.initials: S
authors.lastname: Nelson
authors.forename: C
authors.initials: C
authors.lastname: Chidiac
authors.forename: G
authors.initials: G
authors.lastname: Beaucaire
authors.forename: W R
authors.initials: WR
authors.lastname: Summer
authors.forename: C M
authors.initials: CM
authors.lastname: Mason
mesh_terms: D000399:Air Pressure; D000818:Animals; D001469:Barotrauma / Q000473:pathology / Q000503:physiopathology*; D015824:Blood-Air Barrier / Q000502:physiology*; D002199:Capillary Permeability / Q000502:physiology; D015633:Extravascular Lung Water / Q000502:physiology; D008168:Lung / Q000473:pathology / Q000503:physiopathology; D055370:Lung Injury; D008833:Microcirculation / Q000473:pathology / Q000503:physiopathology; D008855:Microscopy, Electron, Scanning; D010477:Perfusion; D011175:Positive-Pressure Respiration; D011650:Pulmonary Alveoli / Q000098:blood supply / Q000473:pathology; D011669:Pulmonary Wedge Pressure / Q000502:physiology*; D051381:Rats; D012128:Respiratory Distress Syndrome / Q000097:blood / Q000503:physiopathology*; D013990:Tidal Volume / Q000502:physiology