title: A Pilot Randomized Trial Comparing Weaning From Mechanical Ventilation on Pressure Support Versus Proportional Assist Ventilation.
abstract: OBJECTIVE
  Despite protocols incorporating spontaneous breathing trials, 31% of ICU patients experience difficult or prolonged weaning from mechanical ventilation. Nonfatiguing modes such as pressure support ventilation are recommended. Proportional assist ventilation provides assistance in proportion to patient effort, which may optimize weaning. However, it is not known how proportional assist ventilation performs relative to pressure support ventilation over a prolonged period in the complex ICU setting. The purpose of this study was to compare the physiologic and clinical performance (failure rate), safety, and feasibility of protocols using daily spontaneous breathing trial plus pressure support ventilation versus proportional assist ventilation until ventilation discontinuation.
  
  
  METHODS
  Single-center, unblinded pilot randomized controlled trial.
  
  
  METHODS
  Medical-surgical ICU of a tertiary-care hospital.
  
  
  METHODS
  Adult patients intubated greater than 36 hours were randomized if they met eligibility criteria for partial ventilatory support, tolerated pressure support ventilation greater than or equal to 30 minutes, and either failed or did not meet criteria for a spontaneous breathing trial.
  
  
  METHODS
  Patients were randomized to the pressure support ventilation or proportional assist ventilation protocol (PAV+, Puritan Bennett 840; Covidien, Boulder, CO). Both protocols used progressive decreases in level of assistance as tolerated, coupled with daily assessment for spontaneous breathing trials.
  
  
  RESULTS
  Of 54 patients randomized, outcome data are available for 50 patients; 27 were randomized to receive proportional assist ventilation and 23 to receive pressure support ventilation. There were no adverse events linked to the study interventions, and protocol violations were infrequent. Recruitment was slower than projected (1.3 patients per month). The median (interquartile range) time from randomization to successful extubation was 3.9 days (2.8-8.4 d) on proportional assist ventilation versus 4.9 days (2.9-26.3 d) on pressure support ventilation (p = 0.39). Time to live ICU discharge was 7.3 days (5.2-11.4 d) on proportional assist ventilation versus 12.4 days (7.5-30.8 d) on pressure support ventilation (p = 0.03).
  
  
  CONCLUSIONS
  This pilot study demonstrates the utility, safety, and feasibility of the weaning protocols and provides important information to guide the design of a future randomized controlled trial comparing weaning from mechanical ventilation on pressure support ventilation versus proportional assist ventilation.
authors.affiliation: 1London Health Sciences Centre, London, ON, Canada. 2Department of Medicine, The University of Western Ontario, London, ON, Canada.
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Bosma
authors.forename: Brooke A
authors.initials: BA
authors.lastname: Read
authors.forename: Mohammad J
authors.initials: MJ
authors.lastname: Bahrgard Nikoo
authors.forename: Philip M
authors.initials: PM
authors.lastname: Jones
authors.forename: Fran A
authors.initials: FA
authors.lastname: Priestap
authors.forename: James F
authors.initials: JF
authors.lastname: Lewis
mesh_terms: D000368:Aged; D060666:Airway Extubation; D014150:Antipsychotic Agents / Q000008:administration & dosage; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage; D007362:Intensive Care Units; D059725:Interactive Ventilatory Support / Q000009:adverse effects; D007384:Intermittent Positive-Pressure Breathing / Q000009:adverse effects; D007902:Length of Stay; D008297:Male; D000072277:Maximal Respiratory Pressures; D008875:Middle Aged; D009294:Narcotics / Q000008:administration & dosage; D010865:Pilot Projects; D011446:Prospective Studies; D013990:Tidal Volume; D013997:Time Factors; D015300:Ventilator Weaning / Q000379:methods*
chemical_list: D014150:Antipsychotic Agents; D006993:Hypnotics and Sedatives; D009294:Narcotics