title: The effects of positive end-expiratory pressure in alveolar recruitment during mechanical ventilation in pigs.
abstract: OBJECTIVE
  To evaluate the effects of alveolar recruitment based on mean airway pressure (MAP) on pig lungs submitted to thoracotomy through blood gas exchange and hemodynamic parameters.
  
  
  METHODS
  Twelve pigs weighting approximately 25 Kg were intubated and ventilated on volume controlled ventilation (tidal volume 10 ml/Kg, respiratory rate 16 min, FiO2 1.0, inspiratory:expiratory ratio 1:2, PEEP 5 cmH2O). The animals were then randomized into two groups: control and left lateral thoracotomy. The PEEP was increased at each 15-minute intervals to reach a MAP of 15, 20 and 25 cmH2O, respectively. Hemodynamic, gas exchange and respiratory mechanic data were measured immediately before each PEEP change.
  
  
  RESULTS
  There were no significant differences between both groups in all parameters analyzed (P=1.0). The PaO2, PaCO2, MAP, PAP and plateau pressure were significantly worse at MAP of 25 cmH2O, when compared with the other values of MAP (P=0.001, P=0.039, P=0.001, P=0.016 e P=0.027, respectively). The best pulmonary performance according to the analyzed parameters was observed at MAP of 20 cmH2O.
  
  
  CONCLUSIONS
  PEEP adjusted to MAP of 20 cmH2O resulted in best arterial oxygenation, without compromising the venous return, as opposed to MAP of 25 cmH2O, which caused deterioration of gas exchange, hemodynamics and respiratory mechanic.
authors.affiliation: FFFCMPA, Brazil. gabrielmadke@gmail.com
authors.forename: Gabriel Ribeiro
authors.initials: GR
authors.lastname: Madke
authors.forename: Eduardo Sperb
authors.initials: ES
authors.lastname: Pilla
authors.forename: Pablo Geraldo
authors.initials: PG
authors.lastname: Sanchez
authors.forename: Rafael
authors.initials: R
authors.lastname: Foernges
authors.forename: Gustavo
authors.initials: G
authors.lastname: Grün
authors.forename: Giovani
authors.initials: G
authors.lastname: Vendrami
authors.forename: Eduardo
authors.initials: E
authors.lastname: Fontena
authors.forename: Cristiano Feijó
authors.initials: CF
authors.lastname: Andrade
authors.forename: Paulo Francisco Guerreiro
authors.initials: PF
authors.lastname: Cardoso
mesh_terms: D000818:Animals; D001784:Blood Gas Analysis; D016009:Chi-Square Distribution; D004195:Disease Models, Animal; D006439:Hemodynamics / Q000502:physiology*; D008297:Male; D011175:Positive-Pressure Respiration / Q000379:methods*; D011650:Pulmonary Alveoli / Q000098:blood supply / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012121:Respiration, Artificial / Q000379:methods*; D012128:Respiratory Distress Syndrome / Q000503:physiopathology; D013552:Swine; D013908:Thoracotomy; D013990:Tidal Volume