title: Stress index for positive end-expiratory pressure titration in prone position: a piglet study.
abstract: BACKGROUND
  Prone position ventilation is an important treatment for acute respiratory distress syndrome (ARDS), but chest wall elastance increases in prone position ventilation, and stress index may not reflect the changes in lung mechanics. We therefore investigated the effects of stress index guided PEEP titration on pulmonary mechanics and hemodynamics in the prone position in a piglet acute lung injury model.
  
  
  METHODS
  Ten piglets with severe lavage-induced lung injury were mechanically ventilated in a decremental PEEP trial after full lung recruitment in the prone position. Stress-index PEEP was the level at which the airway pressure stress index was 1, and open-lung PEEP was the level at which it was required to keep the lung open according to computed tomography (CT) scans. Respiratory mechanics, blood gases, hemodynamics, and whole-lung CT were recorded at the two PEEP levels.
  
  
  RESULTS
  Respiratory system elastance and lung elastance were improved in the prone position but the ratio of chest wall elastance and respiratory system elastance was higher in the prone position. There was no significant difference between open-lung and stress-index guided PEEPs in the prone position (P = 0.46). There was no significant difference between collapsed lung volume (P = 0.07) and hyperinflation lung volume (P = 0.76) in the two groups. Similarly, there was no significant difference between open-lung and stress-index guided PEEPs in terms of oxygenation index (P = 0.95) and PaCO2 (P = 0.42).
  
  
  CONCLUSIONS
  Stress index can be used to titrate PEEP in the prone position in a surfactant-depleted lung injury model.
authors.affiliation: Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China.
authors.forename: C
authors.initials: C
authors.lastname: Pan
authors.affiliation: Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China.|Department of Critical Care Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China.
authors.forename: R
authors.initials: R
authors.lastname: Tang
authors.affiliation: Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China.
authors.forename: J
authors.initials: J
authors.lastname: Xie
authors.affiliation: Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China.
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China.
authors.forename: S
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China.
authors.forename: T
authors.initials: T
authors.lastname: Yu
authors.affiliation: Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China.
authors.forename: F
authors.initials: F
authors.lastname: Guo
authors.affiliation: Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China.
authors.forename: H
authors.initials: H
authors.lastname: Qiu
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D008168:Lung / Q000503:physiopathology*; D011175:Positive-Pressure Respiration; D016684:Prone Position; D012128:Respiratory Distress Syndrome / Q000503:physiopathology*; D015656:Respiratory Mechanics / Q000502:physiology*; D013552:Swine; D013990:Tidal Volume / Q000502:physiology