ANALYSIS OF THE RESPIRATORY PATTERN AND THORACOABDOMINAL MOTION PATTERN
AT REST AND AFTER SUB-MAXIMUM EFFORT IN ASTHMATIC CHILDREN
Abstract
Introduction: Asthma involves an increase in airway resistance even in
periods between attacks, which generates changes in thoracoabdominal
kinematics as well as adaptations of the respiratory dynamics that are
intensified during physical exertion. The aim of the present study was
to detect these adaptations at rest and after physical effort. Methods:
A cross-sectional study was conducted. Evaluations were performed using
optoelectronic plethysmography at rest and immediately after physical
effort of moderate intensity. Results: Thirty-two children and
adolescents participated in the present study. Mean age was 8.9 ± 2.4
years in the asthmatic group (AG) and 10 ± 3.9 in the healthy control
group (CG). Significant intergroup differences (p < 0.05) were
found regarding FEV1 (%) (84.8 ± 10.2 in the AG and 104.4 ± 20.1 in the
CG). After exercise, the AG exhibited a smaller change in minute volume
(3.4 vs. 4.9 liters) as well as a smaller change in tidal volume (66 vs.
153 ml), and a smaller change in respiratory rate (2 vs. 6). Opposite
kinematic behavior was found; the contribution of the thoracic
compartment was greater at rest and was reduced after effort in the AG,
whereas the contribution of the abdominal compartment was greater at
rest and was reduced after effort in the CG. Expiratory time was greater
in the AG than the CG at both evaluation times. Conclusion: The
kinematic behavior of thoracoabdominal motion was the inverse of that
found in healthy controls. These findings suggest mechanical and
physiological adaptations to minimize the possible swirling of the
airflow and reduce the impact of airway resistance during physical
exertion. Moreover, these changes are found even at rest and in patients
whose asthma is clinically controlled.