Effect of Heliox- and Air-Driven Nebulized Bronchodilator Therapy on Lung Function in Patients with Asthma

Background

This study compares the effect of heliox-driven to that of air-driven bronchodilator therapy on the pulmonary function test (PFT) in patients with different levels of asthma severity.

Methods

One-hundred thirty-two participants were included in the study. Participants underwent spirometry twice with bronchodilator testing on two consecutive days. Air-driven nebulization was used one day and heliox-driven nebulization the other day in random order crossover design. After a baseline PFT, each participant received 2.5 mg of albuterol sulfate nebulized with the randomized driving gas. Post bronchodilator PFT was repeated after 30 min. The next day, the exact same protocol was repeated, except that the other driving gas was used to nebulize the drug. Participants were subgrouped and analyzed according to their baseline FEV₁ on day 1: Group I, FEV₁ ≥80 %; Group II, 80 % > FEV₁ > 50 %; Group III, FEV₁ ≤50 %. The proportion of participants with greater than 12 % and 200-mL increases from their baseline FEV₁ and the changes from baseline in PFT variables were compared between heliox-driven versus air-driven bronchodilation therapy.

Results

The proportion of participants with >12 % and 200-mL increases from their baseline FEV₁ with air- or heliox-driven bronchodilation was not different with respect to the proportion of participants with baseline FEV₁ ≥80 % (20 vs. 18 %, respectively) and 80 % > FEV₁ > 50 % (36 vs. 43 %, respectively), but it was significantly greater with heliox-driven bronchodilation in participants with FEV₁ ≤50 % (43 vs. 73 %, respectively; p = 0.01). Changes from baseline FVC, FEV₁, FEV₁/FVC, FEF_25–75 %, FEF_max, FEF_25 %, FEF_50 %, and FEF_75 % were significantly larger with heliox-driven versus air-driven bronchodilation in participants with baseline FEV₁ ≤50 %.

Conclusion

Improvements in PFT variables are more frequent and profound with heliox-driven compared to air-driven bronchodilator therapy only in asthmatic patients with baseline FEV₁ ≤50 %.