title: Randomized controlled trial comparing adaptive-support ventilation with pressure-regulated volume-controlled ventilation with automode in weaning patients after cardiac surgery.
abstract: BACKGROUND
  Adaptive-support ventilation (ASV) is a minute ventilation-controlled mode governed by a closed-loop algorithm. With ASV, tidal volume and respiratory rate are automatically adjusted to minimize work of breathing. Studies indicate that ventilation in ASV enables more rapid weaning. The authors conducted a randomized controlled trial to determine whether ventilation in ASV results in a shorter time to extubation than pressure-regulated volume-controlled ventilation with automode (PRVCa) after cardiac surgery.
  
  
  METHODS
  Fifty patients were randomly assigned to ASV or PRVCa after elective coronary artery bypass grafting. Respiratory weaning progressed through three phases: phase 1 (controlled ventilation), phase 2 (assisted ventilation), and phase 3 (T-piece trial), followed by extubation. The primary outcome was duration of intubation (sum of phases 1-3). Secondary outcomes were duration of mechanical ventilation (sum of phases 1 and 2), number of arterial blood gas samples, and manual ventilator setting changes made before extubation.
  
  
  RESULTS
  Forty-eight patients completed the study. The median duration of intubation was significantly shorter in the ASV group than in the PRVCa group (300 [205-365] vs. 540 [462-580] min; P < 0.05). This difference was due to a reduction in the duration of mechanical ventilation (165 [120-195] vs. 480 [360-510] min; P < 0.05). There were no significant differences between the ASV and PRVCa groups in the number of arterial blood gas samples taken or manual ventilator setting changes made.
  
  
  CONCLUSIONS
  ASV is associated with earlier extubation, without an increase in clinician intervention, when compared with PRVCa in patients undergoing uncomplicated cardiac surgery.
authors.affiliation: Department of Anesthesia and Intensive Care, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China. pascalegruber@yahoo.com
authors.forename: Pascale C
authors.initials: PC
authors.lastname: Gruber
authors.forename: Charles D
authors.initials: CD
authors.lastname: Gomersall
authors.forename: Patricia
authors.initials: P
authors.lastname: Leung
authors.forename: Gavin M
authors.initials: GM
authors.lastname: Joynt
authors.forename: Siu Keung
authors.initials: SK
authors.lastname: Ng
authors.forename: Ka-Man
authors.initials: KM
authors.lastname: Ho
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: Underwood
mesh_terms: D000368:Aged; D001026:Coronary Artery Bypass; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011182:Postoperative Care / Q000379:methods*; D012121:Respiration, Artificial / Q000379:methods*; D013903:Thoracic Surgery; D015300:Ventilator Weaning / Q000379:methods*