title: Proportional assist ventilation with load-adjustable gain factors in critically ill patients: comparison with pressure support.
abstract: OBJECTIVE
  It is not known if proportional assist ventilation with load-adjustable gain factors (PAV+) may be used as a mode of support in critically ill patients. The aim of this study was to examine the effectiveness of sustained use of PAV+ in critically ill patients and compare it with pressure support ventilation (PS).
  
  
  METHODS
  Randomized study in the intensive care unit of a university hospital.
  
  
  METHODS
  A total of 208 critically ill patients mechanically ventilated on controlled modes for at least 36 h and meeting certain criteria were randomized to receive either PS (n = 100) or PAV+ (n = 108). Specific written algorithms were used to adjust the ventilator settings in each mode. PAV+ or PS was continued for 48 h unless the patients met pre-defined criteria either for switching to controlled modes (failure criteria) or for breathing without ventilator assistance.
  
  
  RESULTS
  Failure rate was significantly lower in PAV+ than that in PS (11.1 vs. 22.0%, P = 0.040, OR 0.443, 95% CI 0.206-0.952). The proportion of patients exhibiting major patient-ventilator dyssynchronies at least during one occasion and after adjusting the initial ventilator settings, was significantly lower in PAV+ than in PS (5.6 vs. 29.0%, P < 0.001, OR 0.1, 95% CI 0.06-0.4). The proportion of patients meeting criteria for unassisted breathing did not differ between modes.
  
  
  CONCLUSIONS
  PAV+ may be used as a useful mode of support in critically ill patients. Compared to PS, PAV+ increases the probability of remaining on spontaneous breathing, while it considerably reduces the incidence of patient-ventilator asynchronies.
authors.affiliation: Intensive Care Medicine Department, University Hospital of Heraklion, Medical School, University of Crete, Heraklion, Crete, Greece.
authors.forename: Nektaria
authors.initials: N
authors.lastname: Xirouchaki
authors.forename: Eumorfia
authors.initials: E
authors.lastname: Kondili
authors.forename: Katerina
authors.initials: K
authors.lastname: Vaporidi
authors.forename: George
authors.initials: G
authors.lastname: Xirouchakis
authors.forename: Maria
authors.initials: M
authors.lastname: Klimathianaki
authors.forename: George
authors.initials: G
authors.lastname: Gavriilidis
authors.forename: Evi
authors.initials: E
authors.lastname: Alexandopoulou
authors.forename: Maria
authors.initials: M
authors.lastname: Plataki
authors.forename: Christina
authors.initials: C
authors.lastname: Alexopoulou
authors.forename: Dimitris
authors.initials: D
authors.lastname: Georgopoulos
mesh_terms: D000368:Aged; D016009:Chi-Square Distribution; D016638:Critical Illness; D023381:Endpoint Determination; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration / Q000379:methods*; D018709:Statistics, Nonparametric; D016896:Treatment Outcome; D014939:Work of Breathing / Q000502:physiology*