Thoracoabdominal asynchrony contributes to exercise limitation in mild asthmatic subjects

Guilherme Fregonezi,Antonella Lomauro,Antonio Sarmento,Andrea Aliverti,Vanessa Resqueti,Janaína Pinto

doi:10.1183/13993003.congress-2018.oa481

Abstract

To better understand how subjects with stable asthma and without exercise-induced bronchoconstriction respond to mild exercise. Breathing pattern, chest wall compartmental and operational volumes and thoracoabdominal asynchrony were assessed in 11 stable asthmatic subjects and 10 healthy at rest and during exercise in a cycle-ergometer through optoelectronic plethysmography. Dyspnea and sensation of leg effort were assessed through Borg scale. During exercise, with similar minute ventilation, a significant lower chest wall tidal volume (p=0.003), as well as a higher respiratory rate (p

Highlights

The maintenance of steady lung volumes during exercise in healthy subjects requires a fine coordination action between inspiratory and expiratory muscles
The aim of the present study was to study how mild asthmatic subjects without exercise-induced bronchoconstriction respond to mild exercise and the possible mechanisms leading to exercise limitation
Asthmatic subjects showed a significantly lower (p < 0.0001) forced vital capacity (FVC) and forced expiratory volume in the 1st s (FEV1) when compared to controls and a significant higher (p < 0.05) FVC and FEV1 after the use of the bronchodilator

Summary

Introduction

The maintenance of steady lung volumes during exercise in healthy subjects requires a fine coordination action between inspiratory and expiratory muscles. This coordination prevents ribcage distortion and makes the diaphragm acting as the main flow generator and the expiratory muscles to decrease abdominal volume and elevate pleural and alveolar pressures in order to decrease end-expiratory volume (EEV) (Henke et al, 1988; Aliverti et al, 1997). Differently from COPD (Aliverti et al, 2009; Priori et al, 2013; O’Donnell et al, 2017), little is known about the thoracoabdominal asynchrony and ventilatory responses in asthmatic subjects during exercise

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