title: Heliox therapy in acute severe asthma.
abstract: OBJECTIVE
  To assess how patients with respiratory acidosis from acute severe asthma respond to helium-oxygen (heliox) mixtures.
  
  
  METHODS
  Consecutive case series.
  
  
  METHODS
  Urban community teaching hospital.
  
  
  METHODS
  Over a 2-year period, 12 asthmatics (mean age, 33.8 +/- 11.3 years) presented to the emergency department with acute respiratory acidosis (pH < 7.35 and PaCO2 > or = 45 mm Hg). All 12 patients were treated with heliox (60 to 70% helium/30 to 40% oxygen). Five patients received heliox through a ventilator and seven received heliox via face mask.
  
  
  RESULTS
  Arterial blood gases (ABGs) were drawn immediately before and at a mean of 49.2 +/- 25.2 min after beginning heliox therapy. No therapeutic interventions were made between ABGs. For the entire group, the mean PaCO2 decreased from 57.9 to 47.5 mm Hg (p < 0.005) and the arterial pH increased from 7.23 to 7.32 (p < 0.001). In an attempt to find characteristics that might predict the response to heliox, a clinically significant response to heliox was defined as a drop in PaCO2 (to normal or by > or = 15%) coupled with a rise in pH by > or = 0.05. Using this definition, there were eight responders (67%) and four nonresponders (33%). The responders had a shorter duration of symptoms (17.8 vs 78.0 h, p < 0.05) and a lower preheliox pH (7.20 vs 7.30, p < 0.05). All of the responders presented within 24 h of symptom onset. Three of the four nonresponders reported prolonged (> or = 96 h) duration of symptoms, and two eventually required intubation.
  
  
  CONCLUSIONS
  Heliox can rapidly improve ventilation in patients presenting to an emergency department with acute severe asthma with respiratory acidosis and a short duration of symptoms.
authors.affiliation: Department of Medicine, Cooper Hospital/University Medical Center, UMDNJ/Robert Wood Johnson School of Medicine at Camden.
authors.forename: J E
authors.initials: JE
authors.lastname: Kass
authors.forename: R J
authors.initials: RJ
authors.lastname: Castriotta
mesh_terms: D000142:Acidosis, Respiratory / Q000209:etiology / Q000628:therapy; D000208:Acute Disease; D000328:Adult; D001249:Asthma / Q000150:complications / Q000188:drug therapy*; D005260:Female; D006371:Helium / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D010100:Oxygen / Q000627:therapeutic use*
chemical_list: D006371:Helium; C038949:heliox; D010100:Oxygen