title: Variable ventilation improves perioperative lung function in patients undergoing abdominal aortic aneurysmectomy.
abstract: BACKGROUND
  Optimizing perioperative mechanical ventilation remains a significant clinical challenge. Experimental models indicate that "noisy" or variable ventilation (VV)--return of physiologic variability to respiratory rate and tidal volume--improves lung function compared with monotonous control mode ventilation (CV). VV was compared with CV in patients undergoing abdominal aortic aneurysmectomy, a patient group known to be at risk of deteriorating lung function perioperatively.
  
  
  METHODS
  After baseline measurements under general anesthesia (CV with a tidal volume of 10 ml/kg and a respiratory rate of 10 breaths/min), patients were randomized to continue CV or switch to VV (computer control of the ventilator at the same minute ventilation but with 376 combinations of respiratory rate and tidal volume). Lung function was measured hourly for the next 6 h during surgery and recovery.
  
  
  RESULTS
  Forty-one patients for aneurysmectomy were studied. The characteristics of the patients in the two groups were similar. Repeated-measures analysis of variance (group x time interaction) revealed greater arterial oxygen partial pressure (P = 0.011), lower arterial carbon dioxide partial pressure (P = 0.012), lower dead space ventilation (P = 0.011), increased compliance (P = 0.049), and lower mean peak inspiratory pressure (P = 0.013) with VV.
  
  
  CONCLUSIONS
  The VV mode of ventilation significantly improved lung function over CV in patients undergoing abdominal aortic aneurysmectomy.
authors.affiliation: Department of Anesthesia and Critical Care, Abdulaziz University, Jeddah, Saudi Arabia.
authors.forename: Abdulaziz
authors.initials: A
authors.lastname: Boker
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Haberman
authors.forename: Linda
authors.initials: L
authors.lastname: Girling
authors.forename: Randy P
authors.initials: RP
authors.lastname: Guzman
authors.forename: George
authors.initials: G
authors.lastname: Louridas
authors.forename: John R
authors.initials: JR
authors.lastname: Tanner
authors.forename: Mary
authors.initials: M
authors.lastname: Cheang
authors.forename: Bruce W
authors.initials: BW
authors.lastname: Maycher
authors.forename: Dean D
authors.initials: DD
authors.lastname: Bell
authors.forename: Greg J
authors.initials: GJ
authors.lastname: Doak
mesh_terms: D000368:Aged; D017544:Aortic Aneurysm, Abdominal / Q000601:surgery*; D001831:Body Temperature / Q000502:physiology; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008170:Lung Compliance / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D001261:Pulmonary Atelectasis / Q000503:physiopathology; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics; D012727:Sex Characteristics; D012907:Smoking / Q000503:physiopathology; D013990:Tidal Volume / Q000502:physiology