title: The Effect of Ventilation Strategy on Arterial and Cerebral Oxygenation During Laparoscopic Bariatric Surgery.
abstract: BACKGROUND
  We investigated the effect of prolonged inspiratory to expiratory (I/E) ratio ventilation on respiratory mechanics, gas exchange, and regional cerebral oxygen saturation (rSO2) in obese patients undergoing laparoscopic bariatric surgery in the reverse Trendelenburg position.
  
  
  METHODS
  Twenty-eight adult patients scheduled for laparoscopic sleeve gastrectomy were enrolled in this prospective observational study. After anesthesia induction, pressure-controlled ventilation was conducted initially at a conventional I/E ratio of 1:2 and a positive end-expiratory pressure of 5 cmH2O. Twenty minutes after pneumoperitoneum, the I/E ratio was changed to 1:1 for 20 min and then to 2:1 for 20 min. Hemodynamic variables, end-tidal carbon dioxide tension, rSO2, arterial blood gas analysis results, and respiratory variables were recorded.
  
  
  RESULTS
  No significant changes in hemodynamic values and rSO2 were observed during the study. Peak airway pressure was significantly lower, but mean airway pressure and dynamic compliance were significantly higher at I/E ratios of 1:1 and 2:1 than during conventional I/E ratio ventilation. Arterial oxygen tension (PaO2) value was significantly higher (p = 0.009), and alveolar-arterial oxygen tension gradient was lower (p = 0.015) at an I/E ratio of 2:1 than during conventional ratio ventilation.
  
  
  CONCLUSIONS
  The use of prolonged I/E ratio of 2:1 significantly improved respiratory mechanics and arterial oxygenation without causing hemodynamic derangements or cerebral desaturation during laparoscopic bariatric surgery in the reverse Trendelenburg position.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Gachon University, Gil Medical Center, 1198 Guwol-dong, Namdong-gu, Incheon, 405-760, South Korea.
authors.forename: Youn Yi
authors.initials: YY
authors.lastname: Jo
authors.affiliation: Department of Anesthesiology and Pain Medicine, Anesthesiology and Pain Research Institute, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Gachon University, Gil Medical Center, 1198 Guwol-dong, Namdong-gu, Incheon, 405-760, South Korea.
authors.forename: Chun Kon
authors.initials: CK
authors.lastname: Park
authors.affiliation: Department of Anesthesiology and Pain Medicine, Gachon University, Gil Medical Center, 1198 Guwol-dong, Namdong-gu, Incheon, 405-760, South Korea.
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Chang
authors.affiliation: Department of Anesthesiology and Pain Medicine, Gachon University, Gil Medical Center, 1198 Guwol-dong, Namdong-gu, Incheon, 405-760, South Korea. hyun615@gilhospital.com.
authors.forename: Hyun Jeong
authors.initials: HJ
authors.lastname: Kwak
mesh_terms: D000328:Adult; D001158:Arteries; D050110:Bariatric Surgery; D001784:Blood Gas Analysis; D005260:Female; D005743:Gastrectomy; D018475:Head-Down Tilt / Q000502:physiology*; D006439:Hemodynamics; D006801:Humans; D010535:Laparoscopy; D008297:Male; D009765:Obesity / Q000097:blood* / Q000503:physiopathology / Q000601:surgery*; D010100:Oxygen / Q000032:analysis / Q000097:blood*; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012121:Respiration, Artificial; D015656:Respiratory Mechanics / Q000502:physiology
chemical_list: D010100:Oxygen
keywords: Arterial oxygenation; Cerebral oxygenation; Laparoscopic sleeve gastrectomy; Prolonged inspiratory time ventilation