title: Protective effects of continuous positive airway pressure on a nonventilated lung during one-lung ventilation: A prospective laboratory study in rats.
abstract: BACKGROUND
  The use of one-lung ventilation (OLV) to facilitate intrathoracic surgery is a cause of lung injury.
  
  
  OBJECTIVE
  We hypothesised that application of continuous positive airway pressure (CPAP) to a nonventilated lung during OLV would prevent alveolar hypoxia and blood flow shift from the nonventilated to the ventilated lung, thereby attenuating lung injury.
  
  
  METHODS
  Controlled animal study.
  
  
  METHODS
  University laboratory.
  
  
  METHODS
  Adult male Sprague-Dawley rats (n = 4 to 8 per group, depending on experiments).
  
  
  METHODS
  Rats were alternately assigned to one of two ventilation protocol groups: control and CPAP groups. Rats received 240 min of OLV followed by 240 min of two-lung reventilation (re-TLV). The nonventilated lungs of rats in the control group were collapsed during OLV whereas rats in the CPAP group received CPAP (5 cmH2O with 100% oxygen) to the nonventilated lungs.
  
  
  METHODS
  Pulmonary blood flow during OLV was measured by quantification of lung radioactivity after intravenous infusion of indium-labelled macroaggregated albumin. Inflammatory cytokines in the lungs after 240 min of OLV, and after the subsequent 240 min of re-TLV were measured. Additionally, we measured lung wet-to-dry weight ratios after re-TLV. We also measured lung malondialdehyde levels after re-TLV as an indicator of reactive oxygen species produced by reoxygenation.
  
  
  RESULTS
  Application of CPAP attenuated the pulmonary blood flow shift from the nonventilated to the ventilated lung. CPAP decreased the levels of IL-6, CXC chemokine ligand-1 and CC chemokine ligand-2 in both lungs after 240 min of OLV. CPAP also decreased CXC chemokine ligand-1 in the nonventilated lung and CC chemokine ligand-2 in both lungs after re-TLV. Moreover, wet-to-dry weight ratios of both lungs were decreased by application of CPAP. However, lung malondialdehyde concentrations were not affected by CPAP.
  
  
  CONCLUSIONS
  CPAP applied to the nonventilated lung during OLV suppresses blood flow shift and decreases inflammatory cytokines and water content in both lungs. Application of CPAP may attenuate lung injury during and after OLV.
authors.affiliation: From the Department of Anaesthesiology and Critical Care Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Tojo
authors.forename: Takahisa
authors.initials: T
authors.lastname: Goto
authors.forename: Kiyoyasu
authors.initials: K
authors.lastname: Kurahashi
mesh_terms: D000818:Animals; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D018836:Inflammation Mediators / Q000378:metabolism*; D008168:Lung / Q000378:metabolism* / Q000473:pathology; D008297:Male; D061810:One-Lung Ventilation / Q000379:methods*; D011446:Prospective Studies; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D018836:Inflammation Mediators