title: Helium-oxygen reduces work of breathing in mechanically ventilated patients with chronic obstructive pulmonary disease.
abstract: OBJECTIVE
  To evaluate whether helium-oxygen mixture reduces inspiratory work of breathing (WOB) in sedated, paralyzed, and mechanically ventilated patients with acute exacerbation of chronic obstructive pulmonary disease (COPD).
  
  
  METHODS
  Open, prospective, randomized, crossover study in the medical intensive care unit in a university hospital.
  
  
  METHODS
  23 patients admitted for acute exacerbation of COPD and mechanically ventilated.
  
  
  METHODS
  Total WOB (WOBt), elastic WOB (WOBel), resistive WOB (WOBres), and WOB due to PEEPi (WOBPeepi) were measured. Static intrinsic positive end expiratory pressure (PEEPi), static compliance (Crs), inspiratory resistance (Rins), inspiratory (tinsp) and expiratory time constant (texp) were also measured. These variables were compared between air-oxygen and helium-oxygen mixtures.
  
  
  RESULTS
  WOBt significantly decreased with helium-oxygen (2.34+/-1.04 to 1.85+/-1.01 J/l, p<0.001). This reduction was significant for WOBel (1.02+/-0.61 J/l to 0.87+/-0.47, p<0.01), WOBPeepi (0.77+/-0.38 J/l to 0.54+/-0.38, p<0.001), and WOBres (0.55+/-0.19 J/l to 0.44+/-0.24, p<0.05). PEEPi, Rins, tinsp and texp significantly decreased. Crs was unchanged.
  
  
  CONCLUSIONS
  Helium-oxygen mixture decreases WOB in mechanically ventilated COPD patients. Helium-oxygen mixture could be useful to reduce the burden of ventilation.
authors.affiliation: Medical Intensive Care Unit, Hôpital Sainte-Marguerite, 13274 Marseille 9, France. Marc.Gainnier@mail.ap-hm.fr
authors.forename: Marc
authors.initials: M
authors.lastname: Gainnier
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Arnal
authors.forename: Patrick
authors.initials: P
authors.lastname: Gerbeaux
authors.forename: Stéphane
authors.initials: S
authors.lastname: Donati
authors.forename: Laurent
authors.initials: L
authors.lastname: Papazian
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Sainty
mesh_terms: D000368:Aged; D018592:Cross-Over Studies; D005260:Female; D006371:Helium / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D010100:Oxygen / Q000627:therapeutic use*; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000628:therapy*; D012121:Respiration, Artificial; D014939:Work of Breathing / Q000187:drug effects*
chemical_list: D006371:Helium; D010100:Oxygen