title: Comparative effects of helium-oxygen and external positive end-expiratory pressure on respiratory mechanics, gas exchange, and ventilation-perfusion relationships in mechanically ventilated patients with chronic obstructive pulmonary disease.
abstract: OBJECTIVE
  To compare the effects of He/O(2) and external PEEP (PEEPe) on intrinsic PEEP (PEEPi), respiratory mechanics, gas exchange, and ventilation/perfusion (V(A)/Q) in mechanically ventilated COPD patients.
  
  
  METHODS
  Prospective, interventional study in the intensive care unit of a university hospital.
  
  
  METHODS
  Ten intubated, sedated, paralyzed, mechanically ventilated COPD patients studied in the following conditions: (a) baseline settings made by clinician in charge, air/O(2), ZEEP; (b) He/O(2), ZEEP; (c) air/O(2), ZEEP; (d) air/O(2), PEEPe 80% of PEEPi. Measurements at each condition included V(A)/Q by the multiple inert gas elimination technique (MIGET).
  
  
  RESULTS
  PEEPi and trapped gas volume were comparably reduced by He/O(2) (4.2+/-4 vs. 7.7+/-4 cmH(2)O and 98+/-82 vs. 217+/-124 ml, respectively) and PEEPe (4.4+/-1.3 vs. 7.8+/-3.6 cmH(2)O and 120+/-107 vs. 216+/-115 ml, respectively). He/O(2) reduced inspiratory and expiratory respiratory system resistance (15.5+/-4.4 vs. 20.7+/-6.9 and 19+/-9 vs. 28.8+/-15 cmH(2)O l(-1)s(-1), respectively) and plateau pressure (13+/-4 vs. 17+/-6 cmH(2)O). PEEPe increased airway pressures, including total PEEP, and elastance. PaO(2)/FIO(2) was slightly reduced by He/O(2) (225+/-83 vs. 245+/-82) without significant V(A)/Q change.
  
  
  CONCLUSIONS
  He/O(2) and PEEPe comparably reduced PEEPi and trapped gas volume. However, He/O(2) decreased airway resistance and intrathoracic pressures, at a small cost in arterial oxygenation. He/O(2) could offer an attractive option in COPD patients with PEEPi/dynamic hyperinflation.
authors.affiliation: Medical Intensive Care Division, University Hospital, 1211 Geneva 14, Switzerland. jolliet@medecine.unige.ch
authors.forename: Philippe
authors.initials: P
authors.lastname: Jolliet
authors.forename: Christine
authors.initials: C
authors.lastname: Watremez
authors.forename: Jean
authors.initials: J
authors.lastname: Roeseler
authors.forename: J C
authors.initials: JC
authors.lastname: Ngengiyumva
authors.forename: Marc
authors.initials: M
authors.lastname: de Kock
authors.forename: Thierry
authors.initials: T
authors.lastname: Clerbaux
authors.forename: Didier
authors.initials: D
authors.lastname: Tassaux
authors.forename: Marc
authors.initials: M
authors.lastname: Reynaert
authors.forename: Bruno
authors.initials: B
authors.lastname: Detry
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Liistro
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001784:Blood Gas Analysis; D004359:Drug Therapy, Combination; D006371:Helium / Q000008:administration & dosage*; D006801:Humans; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000503:physiopathology / Q000628:therapy*; D011659:Pulmonary Gas Exchange / Q000187:drug effects / Q000502:physiology; D015656:Respiratory Mechanics / Q000187:drug effects / Q000502:physiology; D016896:Treatment Outcome; D014692:Ventilation-Perfusion Ratio / Q000187:drug effects / Q000502:physiology
chemical_list: D006371:Helium