title: Lung Perfusion and Ventilation During Cardiopulmonary Bypass Reduces Early Structural Damage to Pulmonary Parenchyma.
abstract: BACKGROUND
  It is unclear whether maintaining pulmonary perfusion and ventilation during cardiopulmonary bypass (CPB) reduces pulmonary inflammatory tissue injury compared with standard CPB where the lungs are not ventilated and are minimally perfused. In this study, we tested the hypothesis that maintenance of lung perfusion and ventilation during CPB decreases regional lung inflammation, which may result in less pulmonary structural damage.
  
  
  METHODS
  Twenty-seven pigs were randomly allocated into a control group only submitted to sternotomy (n = 8), a standard CPB group (n = 9), or a lung perfusion group (n = 10), in which lung perfusion and ventilation were maintained during CPB. Hemodynamics, gas exchanges, respiratory mechanics, and systemic interleukins (ILs) were determined at baseline (T0), at the end of 90 minutes of CPB (T90), and 180 minutes after CPB (T180). Bronchoalveolar lavage (BAL) ILs were obtained at T0 and T180. Dorsal and ventral left lung tissue samples were examined for optical and electron microscopy.
  
  
  RESULTS
  At T90, there was a transient reduction in PaO2/FIO2 in CPB (126 ± 64 mm Hg) compared with the control and lung perfusion groups (296 ± 46 and 244 ± 57 mm Hg; P < 0.001), returning to baseline at T180. Serum ILs were not different among the groups throughout the study, whereas there were significant increases in BAL IL-6 (P < 0.001), IL-8 (P < 0.001), and IL-10 (P < 0.001) in both CPB and lung perfusion groups compared with the control group. Polymorphonuclear counts within the lung tissue were smaller in the lung perfusion group than in the CPB group (P = 0.006). Electron microscopy demonstrated extrusion of surfactant vesicles into the alveolar spaces and thickening of the alveolar septa in the CPB group, whereas alveolar and capillary histoarchitecture was better preserved in the lung perfusion group.
  
  
  CONCLUSIONS
  Maintenance of lung perfusion and ventilation during CPB attenuated early histologic signs of pulmonary inflammation and injury compared with standard CPB. Although increased compared with control animals, there were no differences in serum or BAL IL in animals receiving lung ventilation and perfusion during CPB compared with standard CPB.
authors.affiliation: From the *Discipline of Anesthesiology, LIM 8 - Laboratory of Anesthesiology, Faculdade de Medicina da Universidade de Sao Paulo, São Paulo, Brazil; †Department of Cardiothoracic Surgery, Instituto do Coração, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil; ‡Department of Pathology, Faculdade de Medicina da Universidade de Sao Paulo, São Paulo, Brazil; §Department of Veterinary Pathology, Faculdade de Medicina Veterinária da Universidade de Sao Paulo, São Paulo, Brazil; and ‖Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Claudia Regina da Costa
authors.initials: CR
authors.lastname: Freitas
authors.forename: Luiz Marcelo Sa
authors.initials: LM
authors.lastname: Malbouisson
authors.forename: Anderson
authors.initials: A
authors.lastname: Benicio
authors.forename: Elnara Marcia
authors.initials: EM
authors.lastname: Negri
authors.forename: Filipe Minussi
authors.initials: FM
authors.lastname: Bini
authors.forename: Cristina Oliveira
authors.initials: CO
authors.lastname: Massoco
authors.forename: Denise Aya
authors.initials: DA
authors.lastname: Otsuki
authors.forename: Marcos Francisco Vidal
authors.initials: MF
authors.lastname: Melo
authors.forename: Maria Jose Carvalho
authors.initials: MJ
authors.lastname: Carmona
mesh_terms: D000818:Animals; D002315:Cardiopulmonary Bypass / Q000009:adverse effects* / Q000639:trends; D008168:Lung / Q000473:pathology*; D008297:Male; D010477:Perfusion / Q000379:methods* / Q000639:trends; D011014:Pneumonia / Q000473:pathology* / Q000517:prevention & control*; D012121:Respiration, Artificial / Q000379:methods* / Q000639:trends; D013552:Swine