Related Experiment Video
Updated: May 18, 2026

Dual Test Gas Pulmonary Diffusing Capacity Measurement During Exercise in Humans Using the Single-Breath Method
Published on: February 2, 2024
Vital capacity and inspiratory capacity as additional parameters to evaluate bronchodilator response in asthmatic
Karen S Azevedo1, Ronir R Luiz, Patricia Rm Rocco
1Laboratory of Pulmonary Function Tests, Institute of Thoracic Diseases, Federal University of Rio de Janeiro, Cidade Universitária, CEP 21941-913, Rio de Janeiro, Brazil. karensodre@hotmail.com
Background:
Bronchodilator response in patients with asthma is evaluated based on post-bronchodilator increase in forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). However, the need for additional parameters, mainly among patients with severe asthma, has already been demonstrated.
Methods:
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.
Results:
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.
Conclusions:
VC may be a useful additional parameter to evaluate bronchodilator response in asthma patients with severe airflow obstruction.
Related Concept Videos
Respiratory Capacities
One key metric is the Inspiratory Capacity (IC), which represents the maximum amount of air that can be inhaled with full effort. IC is calculated by summing the tidal volume and inspiratory reserve volume, typically ranging from 2.4 to 3.6 liters.
The Functional Residual Capacity (FRC) represents the air in the...
Lung Capacity
Respiratory Volumes and Capacities
Respiratory Volumes
Tidal Volume (TV) Tidal volume (TV) is the air inhaled or exhaled in a...
Chronic Obstructive Pulmonary Disease-IV: Assessement and Diagnostic Studies
Medical History
Respiratory Volumes and Capacities I

