title: How do COPD and healthy-lung patients tolerate the reduced volume ventilation strategy during OLV ventilation.
abstract: BACKGROUND
  Although a strategy of tidal volume (V(t)) reduction during the one-lung ventilation (OLV) period is advised in thoracic surgery, the influence of the pre-operative respiratory status on the tolerance of this strategy remains unknown. Therefore, the aim of this study was to compare the pulmonary function between chronic obstructive pulmonary disease (COPD) and healthy-lung patients during the operative and the post-operative period.
  
  
  METHODS
  Forty-eight patients undergoing a planned lobectomy for cancer and presenting either a healthy lung function (n=24) or a moderate COPD stage (n=24) were ventilated without external positive end-expiratory pressure (PEEP) and received 9 ml/kg V(t) during the two-lung ventilation (TLV) period, secondary reduced to 6 ml/kg during the OLV period. Lung function was assessed by peroperative gas exchange, venous admixture, respiratory mechanical parameters and post-operative spirometric measurements.
  
  
  RESULTS
  Although the PaO(2) was superior in the healthy-lung group during the TLV, once the OLV was established, no difference was observed between the two groups. Moreover, the PaO(2)/FiO(2) was proportionally more impaired in the healthy-lung group compared with the COPD group (50 ± 13 vs. 72 ± 19% of the baseline values after exclusion and 32 ± 15 vs. 51 ± 25% after the thoracotomy, P<0.05 for each) as well as the venous admixture. In the post-operative period, a higher decrease was observed in the healthy-lung group for the forced vital capacity and the forced expiratory volume.
  
  
  CONCLUSIONS
  Reducing V(t) to 6 ml/kg without the adjunction of external PEEP during OLV is associated with better preservation of lung function in the case of moderate COPD than in the case of healthy-lung status.
authors.affiliation: Réanimation des Urgences, Pôle Réanimation Urgence SAMU Hyperbarie, Hôpital Sainte-Marguerite, Marseille Cedex 9, France. pierre.michelet@ap-hm.fr
authors.forename: P
authors.initials: P
authors.lastname: Michelet
authors.forename: D
authors.initials: D
authors.lastname: Blayac
authors.forename: A
authors.initials: A
authors.lastname: Vincent
authors.forename: X-B
authors.initials: XB
authors.lastname: D'Journo
authors.forename: G
authors.initials: G
authors.lastname: Perrin
authors.forename: M
authors.initials: M
authors.lastname: Badier
authors.forename: P
authors.initials: P
authors.lastname: Thomas
authors.forename: F
authors.initials: F
authors.lastname: Brégeon
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012123:Pulmonary Ventilation; D012121:Respiration, Artificial / Q000379:methods*; D013147:Spirometry; D013990:Tidal Volume