Chest
Volume 116, Issue 2, August 1999, Pages 296-300
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Clinical Investigations
Asthma
The Effect of Heliox in Acute Severe Asthma: A Randomized Controlled Trial

https://doi.org/10.1378/chest.116.2.296Get rights and content

Study objectives

To evaluate the effect of heliox on airflow obstruction and dyspnea in patients with acute severe asthma.

Design

A prospective, randomized, controlled study.

Setting

A university hospital.

Patients

Twenty-three patients presenting to the emergency department with acute severe asthma were randomized to receive 70%/30% heliox or 30% oxygen.

Measurements

Peak expiratory flow (PEF), dyspnea score, heart rate, respiratory rate (RR), and BP were measured at baseline and 20, 120, 240, 360, and 480 min after starting the test gas. After baseline, the PEF was measured by using the gas that was randomized to the treatment program.

Results

In the first 20 min, there was a 58.4% increase in percent predicted PEF (%PEF) in the heliox group (p < 0.001), whereas there was only a 10.1% increase in %PEF for the oxygen group (p > 0.1). Eighty-two percent of the heliox group had > 25% improvement in %PEF at 20 min, whereas only 17% of the oxygen group did (p < 0.01). The next significant improvement in %PEF in the heliox group occurred at 480 min. At the end of the study in the heliox group, the PEF did not significantly (p > 0.1) change immediately after the heliox was discontinued (270.6 to 264.2 L/min). In the heliox group in the first 20 min, there was a significant decrease in dyspnea score and RR (p < 0.05), but there were no further significant improvements for the rest of the study. In the oxygen group, no variables significantly improved until 360 min.

Conclusion

Heliox rapidly improves airflow obstruction and dyspnea in patients with acute severe asthma and may be useful as a therapeutic bridge until the corticosteroid effect occurs.

Section snippets

Materials and Methods

The study was reviewed and approved by our Institutional Review Committee. We enrolled 23 adult subjects who presented with acute severe asthma to the Cooper Hospital/University Medical Center Emergency Department from 1992 to 1995. Patients between 18 and 50 years of age were eligible if they had a clinically severe exacerbation of asthma, as defined by a peak flow of < 200 L/min after treatment with 5 mg of nebulized albuterol. The diagnosis of asthma was made from the patient's history or

Results

There were no significant differences between the groups for gender, age, smoking history, years of asthma, duration of asthma exacerbation, or arterial blood gas findings (Table 1). Before the study, 20 patients were maintained on an inhaledβ -agonist, 6 patients on theophylline, 3 patients on oral corticosteroids, and 5 patients on inhaled corticosteroids, and there were no significant differences between the groups for these prestudy medications (p > 0.1). Nineteen of the 23 subjects (83%)

Discussion

This is the first study to demonstrate in a prospective, randomized, controlled fashion that heliox causes both a rapid improvement in peak flow and a decrease in dyspnea in adult patients with acute severe asthma that is maintained for at least 8 h. Similar objective improvements have been demonstrated in children.1516 All of the heliox patients had a > 20% increase in %PEF at 20 min, whereas only two patients of the oxygen group did. Helium, because of its lower density than nitrogen or

References (24)

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  • CA Manthous et al.

    Heliox in the treatment of airflow obstruction: a critical review of the literature

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