title: One-lung ventilation induces hyperperfusion and alveolar damage in the ventilated lung: an experimental study.
abstract: BACKGROUND
  One-lung ventilation (OLV) increases mechanical stress in the lung and affects ventilation and perfusion (V, Q). There are no data on the effects of OLV on postoperative V/Q matching. Thus, this controlled study evaluates the influence of OLV on V/Q distribution in a pig model using a gamma camera technique [single-photon emission computed tomography (SPECT)] and relates these findings to lung histopathology after OLV.
  
  
  METHODS
  Eleven anaesthetized and ventilated pigs (V(T)=10 ml kg(-1), Fio2=0.40, PEEP=5 cm H2O) were studied. After lung separation, OLV and thoracotomy were performed in seven pigs (OLV group). During OLV and in a two-lung ventilation (TLV), control group (n=4) ventilation settings remained unchanged. SPECT with (81m)Kr (ventilation) and (99m)Tc-labelled macro-aggregated albumin (perfusion) was performed before, during, and 90 min after OLV/TLV. Finally, lung tissue samples were harvested and examined for alveolar damage.
  
  
  RESULTS
  OLV affected ventilation and haemodynamic variables, but there were no differences between the OLV group and the control group before and after OLV/TLV. SPECT revealed an increase of perfusion in the dependent lung compared with baseline (49-56%), and a corresponding reduction of perfusion (51-44%) in non-dependent lungs after OLV. No perfusion changes were observed in the control group. This resulted in increased low V/Q regions and a shift of V/Q areas to 0.3-0.5 (10(-0.5)-10(-0.3)) in dependent lungs of OLV pigs and was associated with an increased diffuse alveolar damage score.
  
  
  CONCLUSIONS
  OLV in pigs results in a substantial V/Q mismatch, hyperperfusion, and alveolar damage in the dependent lung and may thus contribute to gas exchange impairment after thoracic surgery.
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, D-39120 Magdeburg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Kozian
authors.forename: T
authors.initials: T
authors.lastname: Schilling
authors.forename: F
authors.initials: F
authors.lastname: Fredén
authors.forename: E
authors.initials: E
authors.lastname: Maripuu
authors.forename: C
authors.initials: C
authors.lastname: Röcken
authors.forename: C
authors.initials: C
authors.lastname: Strang
authors.forename: T
authors.initials: T
authors.lastname: Hachenberg
authors.forename: G
authors.initials: G
authors.lastname: Hedenstierna
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D006439:Hemodynamics; D008168:Lung / Q000000981:diagnostic imaging / Q000503:physiopathology; D008171:Lung Diseases / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D011650:Pulmonary Alveoli / Q000473:pathology*; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial / Q000009:adverse effects* / Q000379:methods; D034421:Sus scrofa; D013908:Thoracotomy; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods; D014692:Ventilation-Perfusion Ratio
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen