Two puffs of 90 μg albuterol prior to 3% saline sputum induction results in less FEV-1 decline than single concentration 25 mg/ml methacholine challenge

Background: Assessment of sputum eosinophilia has shown benefit in the diagnosis and monitoring of asthma. However, the possibility of bronchospasm related to the hypertonic saline used in sputum induction appears to have limited this procedure's acceptance in clinical practice. Objective: Because the methacholine (MCH) challenge has been widely accepted as safe in the diagnosis of mild asthma, we sought to compare the safety of SI with 3% hypertonic saline following pretreatment with 2 puffs of 90 μg albuterol to that of a single concentration 25 mg/mL MCH challenge. Methods: We performed a retrospective review of 152 consecutive subjects, 57 with mild asthma and the remaining with other respiratory problems who had undergone both a SI and a MCH challenge at our single site tertiary care referral center. Results: Median reduction of FEV-1 in subjects with and without asthma (n = 152) was 9.95% in the MCH group compared to 35% in the SI group (p value < 0.0001). FEV-1 was reduced in excess of 20% in 33 of 152 (21.7%) MCH challenge tests compared to 1 of 152 (0.66%) SI. Median reduction of FEV-1 in asthmatic subjects (n = 57) was 17.86% in the MCH group compared to 32% in the SI group (p value <0.0001). Conclusions: With regard to potential bronchoconstriction, we conclude that 2 puffs of 90 μg albuterol administered prior to 3% saline sputum induction results in less FEV-1 decline than single concentration 25 mg/mL MCH.