title: Helium-oxygen decreases inspiratory effort and work of breathing during pressure support in intubated patients with chronic obstructive pulmonary disease.
abstract: OBJECTIVE
  To evaluate the impact of helium-oxygen (He/O2) on inspiratory effort and work of breathing (WOB) in intubated COPD patients ventilated with pressure support.
  
  
  METHODS
  Prospective crossover interventional study in the medical ICU of a university hospital.
  
  
  METHODS
  Ten patients.
  
  
  METHODS
  Sequential inhalation (30 min each) of three gas mixtures: (a) air/O2, (b) He/O2 (c) air/O2, at constant FIO2 and level of pressure support.
  
  
  RESULTS
  Inspiratory effort and WOB were determined by esophageal and gastric pressure. Throughout the study pressure support and FIO2 were 14+/-3 cmH2O and 0.33+/-0.07 respectively. Compared to Air/O2, He/O2 reduced the number of ineffective breaths (4+/-5 vs. 9+/-5 breaths/min), intrinsic PEEP (3.1+/-2 vs. 4.8+/-2 cmH2O), the magnitude of negative esophageal pressure swings (6.7+/-2 vs. 9.1+/-4.9 cmH2O), pressure-time product (42+/-37 vs. 67+/-65 cmH2O s(-1) min(-1)), and total WOB (11+/-3 vs. 18+/-10 J/min). Elastic (6+/-1 vs. 10+/-6 J/min) and resistive (5+/-1 vs. 9+/-4 J/min) components of the WOB were decreased by He/O2.
  
  
  CONCLUSIONS
  In intubated COPD patients ventilated with pressure support He/O2 reduces intrinsic PEEP, the number of ineffective breaths, and the magnitude of inspiratory effort and WOB. He/O2 could prove useful in patients with high levels of PEEPi and WOB ventilated in pressure support, for example, during weaning.
authors.affiliation: Medical Intensive Care, University Hospital, 1211, Geneva 14, Switzerland.
authors.forename: Didier
authors.initials: D
authors.lastname: Tassaux
authors.forename: Marc
authors.initials: M
authors.lastname: Gainnier
authors.forename: Anne
authors.initials: A
authors.lastname: Battisti
authors.forename: Philippe
authors.initials: P
authors.lastname: Jolliet
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis; D001794:Blood Pressure; D018592:Cross-Over Studies; D005260:Female; D006371:Helium / Q000627:therapeutic use*; D006801:Humans; D007362:Intensive Care Units; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000627:therapeutic use*; D011175:Positive-Pressure Respiration; D029424:Pulmonary Disease, Chronic Obstructive / Q000628:therapy*; D014939:Work of Breathing / Q000187:drug effects*
chemical_list: D006371:Helium; C038949:heliox; D010100:Oxygen