title: Physiological effects of constant versus decelerating inflation flow in patients with chronic obstructive pulmonary disease under controlled mechanical ventilation.
abstract: OBJECTIVE
  To study the cardiorespiratory effects of inspiratory flow rate and waveform in COPD patients.
  
  
  METHODS
  Prospective physiological investigation with randomized allocations of experimental conditions.
  
  
  METHODS
  A 14-bed medical ICU in a 1000-bed university hospital.
  
  
  METHODS
  Ten COPD intubated, sedated and paralyzed patients with chronic obstructive pulmonary disease (COPD), mechanically ventilated for acute respiratory failure.
  
  
  METHODS
  In volume-controlled mode, three inflation flow rates of 0.40, 0.70, and 1.10 l/s for 20 min with a constant (CF) or a decelerating (DF) inflation flow profile. Each patient received all six experimental conditions in a random order. Tidal volume and respiratory frequency were similar during the experimental conditions.
  
  
  RESULTS
  Arterial blood gases, hemodynamics ( n=8), and respiratory mechanics were measured with zero end expiratory pressure. Between flow rates the median (25th-75th percentiles) values of PaO(2)/FIO(2) were 232 (132-289), 253 (161-338), 231 (163-352) for CF and 253 (143-331), 249 (164-360), 231 mmHg (187-351), for DF, respectively; the maximal airway pressures were 25.6, 28.3, 34.6 cmH(2)O for CF and 21.7, 29.6, 34.8 cmH(2)O for DF, respectively, the mean airway pressures were 8.9, 6.1, 5.4 cmH(2)O for CF and 9.1, 7, 6.5 cmH(2)O for DF, respectively.
  
  
  CONCLUSIONS
  Changing the ventilator in volume-controlled mode with a DF or CF profile has no significant cardiorespiratory effect in intubated COPD patients mechanically ventilated for acute respiratory failure.
authors.affiliation: Service de Réanimation Médicale, Centre Hospitalier Lyon-Sud, 69495 Pierre-Bénite Cedex, France. c-guerin@univ-lyon1.fr
authors.forename: Claude
authors.initials: C
authors.lastname: Guérin
authors.forename: Stéphane
authors.initials: S
authors.lastname: Lemasson
authors.forename: Maria Filippa
authors.initials: MF
authors.lastname: La Cara
authors.forename: Gérard
authors.initials: G
authors.lastname: Fournier
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis; D005260:Female; D005602:France; D006439:Hemodynamics; D006785:Hospitals, University; D006801:Humans; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000628:therapy; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial / Q000379:methods*; D015656:Respiratory Mechanics