Salbutamol Reversal of Methacholine Induced Bronchoconstriction: Vibrating Mesh Nebulizer versus Pressurized Metered Dose Inhaler.

Abstract

<h4>Background</h4>Reversal of methacholine induced bronchoconstriction (MIB) is routinely achieved by administering 200 mcg salbutamol via pressurized metered dose inhaler (pMDI). The propellant in the inhaler (hydrofluoroalkane-134a) contributes to greenhouse gas emissions, negatively impacting the environment. One alternative to delivering bronchodilator would be using the Aerogen^® Solo vibrating mesh nebulizer (VMN). Using the VMN to deliver methacholine during MCT as well as bronchodilator after MCT could reduce the carbon footprint of testing by eliminating pMDI inhaler use. The current study compared bronchodilator reversal of MIB via pMDI to that of VMN.<h4>Methods</h4>Sixteen individuals exhibiting airway hyperresponsiveness to methacholine completed a double blind, double dummy, placebo controlled, randomized, three-way crossover study. At each visit, participants underwent MCT followed by administration of placebo or salbutamol (200 mcg) via pMDI or VMN. Lung function and heart rate measurements were captured before and at 5, 10, 15, 30, 45 and 60 minutes after treatment administration.<h4>Results</h4>Pre MCT FEV₁ did not differ between the three treatment arms (RM ANOVA p = 0.741). When corrected for repeated measures, the reduction in FEV₁ after MCT (30.5%, 27.4% and 24.8% for placebo, pMDI and VMN, respectively) was similar across groups. Mean FEV₁ values after administration of salbutamol via pMDI or VMN were significantly greater than after placebo at all timepoints (RM ANOVA p < 0.001) with no significant difference between methods of salbutamol administration. Mean heartrate did not differ between treatments before or after treatment.<h4>Conclusion</h4>Use of the VMN for delivering salbutamol to reverse MIB is feasible. Doing so adds functionality to the use of this nebulizer for performing methacholine bronchoprovocation and reduces the negative environmental impact of pMDI inhalers.