title: Pressure-controlled ventilation improves oxygenation during laparoscopic obesity surgery compared with volume-controlled ventilation.
abstract: BACKGROUND
  We compared pressure and volume-controlled ventilation (PCV and VCV) in morbidly obese patients undergoing laparoscopic gastric banding surgery.
  
  
  METHODS
  Thirty-six patients, BMI>35 kg m(-2), no major obstructive or restrictive respiratory disorder, and Pa(CO(2))<6.0 kPa, were randomized to receive either VCV or PCV during the surgery. Ventilation settings followed two distinct algorithms aiming to maintain end-tidal CO(2) (E'(CO(2))) between 4.40 and 4.66 kPa and plateau pressure (P(plateau)) as low as possible. Primary outcome variable was peroperative P(plateau). Secondary outcomes were Pa(O(2)) (Fi(O(2)) at 0.6 in each group) and Pa(CO(2)) during surgery and 2 h after extubation. Pressure, flow, and volume time curves were recorded.
  
  
  RESULTS
  There were no significant differences in patient characteristics and co-morbidity in the two groups. Mean pH, Pa(O(2)), Sa(O(2)), and the Pa(O(2))/Fi(O(2)) ratio were higher in the PCV group, whereas Pa(CO(2)) and the E'(CO(2))-Pa(CO(2)) gradient were lower (all P<0.05). Ventilation variables, including plateau and mean airway pressures, anaesthesia-related variables, and postoperative cardiovascular variables, blood gases, and morphine requirements after the operation were similar.
  
  
  CONCLUSIONS
  The changes in oxygenation can only be explained by an improvement in the lungs ventilation/perfusion ratio. The decelerating inspiratory flow used in PCV generates higher instantaneous flow peaks and may allow a better alveolar recruitment. PCV improves oxygenation without any side-effects.
authors.affiliation: Department of Anaesthesia and Intensive Care Unit, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, 20-40, rue Leblanc, 75908 Paris Cedex 15, France. pcadi@invivo.edu
authors.forename: P
authors.initials: P
authors.lastname: Cadi
authors.forename: T
authors.initials: T
authors.lastname: Guenoun
authors.forename: D
authors.initials: D
authors.lastname: Journois
authors.forename: J-M
authors.initials: JM
authors.lastname: Chevallier
authors.forename: J-L
authors.initials: JL
authors.lastname: Diehl
authors.forename: D
authors.initials: D
authors.lastname: Safran
mesh_terms: D000328:Adult; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D015391:Gastroplasty / Q000379:methods*; D006339:Heart Rate; D006801:Humans; D010535:Laparoscopy; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000503:physiopathology / Q000601:surgery*; D010100:Oxygen / Q000097:blood*; D010313:Partial Pressure; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial / Q000379:methods*; D015656:Respiratory Mechanics
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen