title: Evaluation of heliox in children hospitalized with acute severe asthma. A randomized crossover trial.
abstract: OBJECTIVE
  To determine whether breathing a blend of 70% helium:30% oxygen (heliox) would improve pulmonary function, decrease clinical score, and improve the sensation of dyspnea in children hospitalized with acute severe asthma.
  
  
  METHODS
  Prospective, randomized, double-blind, crossover study.
  
  
  METHODS
  The inpatient pediatric service of a military, tertiary care, teaching hospital.
  
  
  METHODS
  Children 5 to 18 years who required hospital admission for treatment of acute asthma.
  
  
  METHODS
  All patients received 5 mg of nebulized albuterol every 1 to 4 h, with a dose given within 30 min of the start of the study, and IV administered methylprednisolone. Patients breathed heliox and a 30% oxygen-enriched air mixture for 15 min each in random order.
  
  
  RESULTS
  Clinical score, dyspnea score, oxygen saturation, heart rate, and respiratory rate, followed by FVC, FEV1, peak expiratory flow rate (PEFR), and, mean midexpiratory flow rate (FEF25-75) were obtained at study entry, 15 min after breathing the first gas mixture (heliox or air per randomization), 15 min after breathing the second mixture, and again 15 min after stopping the second gas mixture (study end values). Eleven children were enrolled, and all completed the study. There were no significant differences between study entry and study end spirometric values. Using the paired t test, we found no significant differences between mean values (SD) of FEV1 and FVC obtained while breathing heliox vs air; FEV1-heliox, 53% (18%) of the predicted value; FEV1-air, 52% (16%) of the predicted value (p = 0.36); FVC-heliox, 69% (22%) of the predicted value; and FVC-air, 70% (21%) of the predicted value (p = 0.50). The differences in values for PEFSR and FEF25-75 while breathing heliox vs air were small but did reach statistical significance in favor of heliox: PEFR-heliox, 56% (20%) of the predicted value; PEFR-air, 50% (16%) of the predicted value (p = 0.04); FEF25-75-heliox, 32% (13%) of the predicted value; and FEF25-75-heliox, 29% (11%) of the predicted value (p = 0.006). Heliox had no effect on either clinical or dyspnea scores.
  
  
  CONCLUSIONS
  The short-term inhalation of heliox did not benefit this group of children hospitalized with acute, severe asthma.
authors.affiliation: Division of Pediatric Pulmonology, Madigan Army Medical Center, Tacoma, Wash 98410-5000, USA.
authors.forename: E R
authors.initials: ER
authors.lastname: Carter
authors.forename: C R
authors.initials: CR
authors.lastname: Webb
authors.forename: D R
authors.initials: DR
authors.lastname: Moffitt
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D001249:Asthma / Q000503:physiopathology / Q000628:therapy*; D002648:Child; D002675:Child, Preschool; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D005541:Forced Expiratory Volume; D006371:Helium / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008450:Maximal Midexpiratory Flow Rate; D010100:Oxygen / Q000627:therapeutic use*; D010366:Peak Expiratory Flow Rate; D011237:Predictive Value of Tests; D011446:Prospective Studies; D014797:Vital Capacity
chemical_list: D006371:Helium; C038949:heliox; D010100:Oxygen