Heliox-Driven Vs. Air-Driven Nebulized Bronchodilator (BD) Therapy and Pulmonary Function Tests (PFT) in Patients With Obstructive Lung Diseases

Abstract

PURPOSE: To compare the effect of heliox-driven (Helium 80%: Oxygen 20%) to air-driven (Nitrogen 79%; Oxygen 21%) BD therapy on PFTs in patients with different levels of severity of airway obstructions. METHODS: 150 patients undergoing their first pre- and post-bronchodilator PFT measurements were included in the study. Pregnant women and morbidly obese patients were excluded. Each patient was studied on two consecutive days with random assignment to receive either air-driven nebulization of 2.5mg of albuterol sulfate on day one and heliox-driven nebulization of same drug on day two or vice versa. After baseline PFT on day one, each patient received the nebulized bronchodilator treatment for 10 minutes at a flow rate of 8L/min with the randomized driving gas for day one. Post bronchodilator PFT was repeated after 30 minutes. The next day, the exact protocol was performed except that the other driving gas was used to nebulize the drug. The patients and the staff conducting the PFTs were blinded to the driving gas. Patients were sub-grouped and analyzed according to their baseline FEV1 on day one: 100%>FEV1>80%; 80%>FEV1>50%; FEV1<50%. Changes from baseline in PFT variables were compared with heliox-driven versus air-driven bronchodilation therapy. RESULTS: The percentages of patients who showed >12% increases in FEV1 with either heliox-driven or air-driven bronchodilation were not different in patients with 100%>FEV1>80% (20% vs. 20%) and 80%>FEV1>50% (38% vs. 28%) but significantly greater in patients with FEV1<50% (58% vs. 18%). Only in patients with FEV1<50%, changes from baseline in FVC, FEV1, FEV1/FVC, FEF25-75%, FEFmax, FEF25%, FEF50%, and FEF75% were larger with heliox-driven versus airdriven bronchodilation. CONCLUSIONS: PFT variables improvements are more frequent and larger with heliox-driven compared to air-driven bronchodilator therapy only in patients with FEV1<50%.