Vital capacity and inspiratory capacity as additional parameters to evaluate bronchodilator response in asthmatic patients: a cross sectional study

The aim of this study was to evaluate the usefulness of vital capacity (VC) and inspiratory capacity (IC) to evaluate bronchodilator response in asthma patients with persistent airflow obstruction. The 43 asthma patients enrolled in the study were stratified into moderate or severe airflow obstruction groups based on baseline FEV1. All patients performed a 6-minute walk test before and after the bronchodilator (BD). A bipolar visual analogue scale post-BD was performed to assess clinical effect. The correlation between VC and IC and clinical response, determined by visual analogue scale (VAS) and 6-minute walk test (6MWT), was investigated.Patients in the severe group presented: 1) greater bronchodilator response in VC (48% vs 15%, p？=？0.02), 2) a significant correlation between VC variation and the reduction in air trapping (Rs？=？0.70; p？<？0.01), 3) a significant agreement between VC and VAS score (kappa？=？0.57; p？<？0.01). There was no correlation between IC and the reduction in air trapping or clinical data.VC may be a useful additional parameter to evaluate bronchodilator response in asthma patients with severe airflow obstruction.Asthma is a serious worldwide health issue, but its clinical manifestations can be controlled with appropriate treatment [1]. Currently, a positive bronchodilator response is established based on an increase？≥？12% and 200 ml in forced vital capacity (FVC) and/or forced expiratory volume in one second (FEV1) compared with baseline values following administration of bronchodilators [2]. However, in clinical practice, patients with moderate or severe asthma may refer clinical improvement after bronchodilator use despite a negative bronchodilator test. In patients with chronic obstructive pulmonary disease (COPD), in whom the bronchodilator test is frequently negative, vital capacity (VC) and inspiratory capacity (IC) variation are used as complementary tools in order to evaluate bronchodilator response [3-6]. COPD patients have a persisten