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Table 4 Changes in ventilator setup

From: Optimization of ventilator setting by flow and pressure waveforms analysis during noninvasive ventilation for acute exacerbations of COPD: a multicentric randomized controlled trial

  All patients Optimized ventilation Standard ventilation P
At the beginning of NIV     
   PEEP, cmH2O 5.1 ± 1.4 5.5 ± 1.7 4.7 ± .9 .003
   PS, cmH2O 13.6 ± 3.4 14.0 ± 3.7 13.2 ± 3.1 .152
   Insp trigger*, L/minute 3.2 ± 2.0 2.3 ± 1.8 4.0 ± 1.7 .002
   Expiratory trigger, % 40 ± 9 38 ± 9 42 ± 8 .086
   Speed of pressurization 1.8 ± .6 1.7 ± .6 2.0 ± .4 .024
After 30 minutes of NIV     
   PEEP, cmH2O 5.4 ± 1.3 5.9 ± 1.4 4.9 ± .9 .011
   PS, cmH2O 14.3 ± 3.5 14.7 ± 3.7 14.0 ± 3.4 .604
   Insp trigger*, L/minute 2.9 ± 2.0 2.0 ± 1.7 3.8 ± 1.8 .001
   Expiratory trigger, % 40 ± 12 40 ± 14 40 ± 9 .600
   Speed of pressurization 1.6 ± .5 1.4 ± .5 1.7 ± .4 .011
After 2 hours of NIV     
   PEEP, cmH2O 5.4 ± 1.2 5.9 ± 1.3 4.9 ± .9 .030
   PS, cmH2O 14.8 ± 3.9 14.9 ± 4.2 14.7 ± 3.7 .820
   Insp trigger*, L/minute 2.9 ± 2.0 1.9 ± 1.7 4.1 ± 1.7 0.001
   Expiratory trigger, % 37 ± 12 36 ± 14 38 ± 10 .337
   Speed of pressurization 1.4 ± .5 1.3 ± .5 1.6 ± .5 .064
After 6 hours of NIV     
   PEEP, cmH2O 5.4 ± 1.4 5.8 ± 1.6 5.1 ± 1.0 .015
   PS, cmH2O 15.3 ± 4.0 15.5 ± 4.2 15.1 ± 4.0 .925
   Insp trigger*, L/minute 3.0 ± 2.0 2.0 ± 1.7 3.9 ± 1.8 .001
   Expiratory trigger, % 37 ± 11 36 ± 12 39 ± 10 .143
   Speed of pressurization 1.6 ± .5 1.5 ± .6 1.7 ± .5 .134
After 24 hours of NIV     
   PEEP, cmH2O 5.4 ± 1.5 6.0 ± 1.8 4.9 ± .9 .002
   PS, cmH2O 14.8 ± 3.9 15.4 ± 4.2 14.3 ± 3.6 .426
   Insp trigger*, L/minute 3.1 ± 1.9 2.4 ± 1.8 4.0 ± 1.8 .009
   Expiratory trigger, % 37 ± 11 37 ± 12 37 ± 10 .708
   Speed of pressurization 1.7 ± .6 1.5 ± .5 1.9 ± .6 .089
  1. Data reported as mean ± standard deviation. Insp trigger, inspiratory trigger; PEEP, external positive end expiratory pressure; PS, pressure support (over PEEP). Speed of pressurization: data are reported in a qualitative scale ranging from 0 (faster pressurization) to 5 (slower pressurization). *Data available in 50 patients. Significant differences in bold.