title: Heliox improves hemodynamics in mechanically ventilated patients with chronic obstructive pulmonary disease with systolic pressure variations.
abstract: OBJECTIVE
  To test the hypothesis that, compared with air-oxygen, heliox would improve cardiac performance in mechanically ventilated patients with severe chronic obstructive pulmonary disease and systolic pressure variations >15 mm Hg and to determine clinical variables associated with favorable hemodynamic responses to heliox.
  
  
  METHODS
  A prospective interventional study.
  
  
  METHODS
  Medical and respiratory intensive care units at a university-affiliated tertiary medical center.
  
  
  METHODS
  Twenty-five consecutive mechanically ventilated patients with severe chronic obstructive pulmonary disease and acute respiratory failure who had systolic pressure variations >15 mm Hg.
  
  
  METHODS
  Respiratory and hemodynamic measurements were taken at the following time with the same ventilator setting: a) baseline; b) after 30 mins with heliox; and c) 30 mins after return to air-oxygen.
  
  
  RESULTS
  Heliox ventilation decreased intrinsic positive end-expiratory pressure (air-oxygen vs. heliox [mean +/- sd] 13 +/- 4 cm H2O vs. 5 +/- 2 cm H2O, p < .05), trapped lung volume (air-oxygen vs. heliox 362 +/- 67 mL vs. 174 +/- 86 mL, p < .05), and respiratory changes in systolic pressure variations (DeltaPP) (air-oxygen vs. heliox 29 +/- 5% vs. 13 +/- 7%, p < .05). In the ten patients with pulmonary arterial catheters, heliox decreased mean pulmonary arterial pressure, right atrial pressure, and pulmonary arterial occlusion pressure and increased cardiac index. Preheliox DeltaPP correlated with the magnitude of reduction in intrinsic positive end-expiratory pressure during heliox ventilation. Age, preheliox Paco2, and ratio of forced expiratory volume at first second to forced vital capacity correlated inversely, whereas preheliox DeltaPP correlated positively with increases in cardiac index.
  
  
  CONCLUSIONS
  Heliox may be a useful adjunct therapy in patients with severe chronic obstructive pulmonary disease during acute respiratory failure who have persistent intrinsic positive end-expiratory pressure-induced hemodynamic changes despite ventilator management.
authors.affiliation: Department of Medicine, Kaohsiung Veterans General Hospital and School of Medicine, National Yang-Ming Medical University, Taiwan, ROC.
authors.forename: David Lin
authors.initials: DL
authors.lastname: Lee
authors.forename: Huan
authors.initials: H
authors.lastname: Lee
authors.forename: Hsueh-Wen
authors.initials: HW
authors.lastname: Chang
authors.forename: Alice Y W
authors.initials: AY
authors.lastname: Chang
authors.forename: Shoa-Lin
authors.initials: SL
authors.lastname: Lin
authors.forename: Yuh-Chin T
authors.initials: YC
authors.lastname: Huang
mesh_terms: D001794:Blood Pressure / Q000187:drug effects*; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006371:Helium / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000627:therapeutic use*; D011175:Positive-Pressure Respiration; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy* / Q000628:therapy; D012121:Respiration, Artificial; D012131:Respiratory Insufficiency / Q000188:drug therapy* / Q000628:therapy
chemical_list: D006371:Helium; C038949:heliox; D010100:Oxygen