title: Prospective randomized trial of heliox-driven continuous nebulizers in the treatment of asthma in the emergency department.
abstract: 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.
authors.affiliation: Division of Emergency Medicine, University of California, Davis Medical Center, Sacramento, California 95817, USA.
authors.forename: John S
authors.initials: JS
authors.lastname: Rose
authors.forename: Edward A
authors.initials: EA
authors.lastname: Panacek
authors.forename: Penny
authors.initials: P
authors.lastname: Miller
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000628:therapy*; D004311:Double-Blind Method; D005260:Female; D005541:Forced Expiratory Volume; D006371:Helium / Q000008:administration & dosage*; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009330:Nebulizers and Vaporizers; D010100:Oxygen / Q000008:administration & dosage*; D010366:Peak Expiratory Flow Rate; D011446:Prospective Studies; D016896:Treatment Outcome
chemical_list: D006371:Helium; C038949:heliox; D010100:Oxygen