title: Bedside adjustment of proportional assist ventilation to target a predefined range of respiratory effort.
abstract: OBJECTIVE
  During proportional assist ventilation with load-adjustable gain factors, peak respiratory muscle pressure can be estimated from the peak airway pressure and the percentage of assistance (gain). Adjusting the gain can, therefore, target a given level of respiratory effort. This study assessed the clinical feasibility of titrating proportional assist ventilation with load-adjustable gain factors with the goal of targeting a predefined range of respiratory effort.
  
  
  METHODS
  Prospective, multicenter, clinical observational study.
  
  
  METHODS
  Intensive care departments at five university hospitals.
  
  
  METHODS
  Patients were included after meeting simple criteria for assisted mechanical ventilation.
  
  
  METHODS
  Patients were ventilated in proportional assist ventilation with load-adjustable gain factors. The peak respiratory muscle pressure, estimated in cm H2O as (peak airway pressure-positive end-expiratory pressure)×[(100-gain)/gain], was calculated from a grid at the bedside. The gain adjustment algorithm was defined to target a peak respiratory muscle pressure between 5 and 10 cm H2O. Additional recommendations were available in case of hypoventilation or hyperventilation.
  
  
  RESULTS
  Fifty-three patients were enrolled. Median time spent under proportional assist ventilation with load-adjustable gain factors was 3 days (interquartile range, 1-5). Gain was adjusted 1.0 (0.7-1.8) times per day, according to the peak respiratory muscle pressure target range in 91% of cases and because of hypoventilation or hyperventilation in 9%. Thirty-four patients were ventilated with proportional assist ventilation with load-adjustable gain factors until extubation, which was successful in 32. Eighteen patients required volume assist-controlled reventilation because of clinical worsening and need for continuous sedation. One patient was intolerant to proportional assist ventilation with load-adjustable gain factors.
  
  
  CONCLUSIONS
  This first study assessing the clinical feasibility of titrating proportional assist ventilation with load-adjustable gain factors in an attempt to target a predefined range of effort showed that adjusting the level of assistance to maintain a predefined boundary of respiratory muscle pressure is feasible, simple, and often sufficient to ventilate patients until extubation.
authors.affiliation: Service de Réanimation Médicale, AP-HP, Centre Hospitalier Albert Chenevier-Henri Mondor, Créteil, France. guillaume.carteaux@yahoo.fr
authors.forename: Guillaume
authors.initials: G
authors.lastname: Carteaux
authors.forename: Jordi
authors.initials: J
authors.lastname: Mancebo
authors.forename: Alain
authors.initials: A
authors.lastname: Mercat
authors.forename: Jean
authors.initials: J
authors.lastname: Dellamonica
authors.forename: Jean-Christophe M
authors.initials: JC
authors.lastname: Richard
authors.forename: Hernan
authors.initials: H
authors.lastname: Aguirre-Bermeo
authors.forename: Achille
authors.initials: A
authors.lastname: Kouatchet
authors.forename: Gaetan
authors.initials: G
authors.lastname: Beduneau
authors.forename: Arnaud W
authors.initials: AW
authors.lastname: Thille
authors.forename: Laurent
authors.initials: L
authors.lastname: Brochard
mesh_terms: D000368:Aged; D000465:Algorithms; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D059725:Interactive Ventilatory Support / Q000379:methods*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D019095:Point-of-Care Systems; D011446:Prospective Studies; D012131:Respiratory Insufficiency / Q000503:physiopathology / Q000628:therapy*; D015656:Respiratory Mechanics; D012141:Respiratory Tract Infections; D015300:Ventilator Weaning / Q000379:methods