Prospective randomized trial of heliox-driven continuous nebulizers in the treatment of asthma in the emergency department

J Emerg Med. 2002 Feb;22(2):133-7. doi: 10.1016/s0736-4679(01)00454-1.


The purpose of this study was to evaluate the efficacy of heliox-driven continuous nebulizers in the management of moderate to severe asthma exacerbations in the Emergency Department (ED). The trial was a prospective, randomized, double-blind, controlled trial in a university Emergency Department (volume 65,000 patients/year) of patients 18-55 years of age with acute asthma exacerbations. Patients were placed on continuous nebulizers driven by 70:30 heliox or air with 30% O(2). Respiratory rate, peak expiratory flow rate (PEFR), forced expiratory volume at 1 s (FEV1), and Borg dyspnea scale were measured at 0 and 2 h. Disposition and patient satisfaction were also assessed. A total of 36 patients completed the study (18 heliox, 18 air). There was no difference between groups in baseline variables. There was significant interval improvement within both groups at 2 h in PEFR, FEV1, Borg, and respiratory rate. There was no significant difference between heliox 70:30 and air/oxygen in PEFR [mean between-group improvement difference 17 liters/min, 95% confidence interval (CI) -20-51], FEV1 (0.03 liters/sec, 95% CI -0.22-0.30), or respiratory rate (mean between-group improvement difference 0.5, 95% CI -2.7-3.8). There was a significant improvement in the patients' perceived dyspnea as measured by the Borg dyspnea scale at 2 h in the heliox group (1.6, 95% CI 0.3-3.0). In this trial of patients with moderate-severe asthma exacerbation, heliox-driven continuous nebulizers failed to demonstrate an improvement in respiratory rate, oxygen saturation, PEFR, or FEV1 at 2 h. However, there was a significant improvement in the patients' perceived dyspnea on heliox over air/oxygen measured by the Borg dyspnea scale.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Asthma / therapy*
  • Double-Blind Method
  • Female
  • Forced Expiratory Volume
  • Helium / administration & dosage*
  • Humans
  • Hypoxia / physiopathology
  • Male
  • Middle Aged
  • Nebulizers and Vaporizers*
  • Oxygen / administration & dosage*
  • Peak Expiratory Flow Rate
  • Prospective Studies
  • Treatment Outcome


  • Helium
  • heliox
  • Oxygen