Chest wall kinematics during exercise in patients with asthma

Abstract

Changes in breathing pattern and operating chest wall volumes,End Expiratory Volum-EEV/End Inspiratory Volume-EIV,during exercise are not well understood in asthmatic patients. In order to highlight possible differences in the regulation of EEV and EIV and breathing pattern between asthmatic and healthy subjects, 10 patients without asthma without Asthma Induce by exercise,(3M/7F,33±11years, FEV1%=59±16 and FVC%=70±16)and 7 healthy subejcts(7M,39±14years,normal lung function),were evaluated during spontaneous breathing and incremental exercise on a cycle-ergometer by measuring total and compartmental chest wall volumes by opto-electronic plethysmography. Exercise protocol:1 min of unloaded pedaling and 30W increments every minute until exhaustion.In asthma, maximal workload was significantly lower(117±35 vs.210± 42,p=0,0076).At maximum workload, tidal volume was significantly lower and respiratory rate higher in asthmatics.At iso-ventilation levels, however, tidal volume was higher at low levels of minute ventilation ( 20 L/min). At iso-workload,EEV was significantly higher in asthmatics(p<0.01),predominantly due to the different behavior in the abdomen.EIV was significantly lower in (p<0.01), mainly due to the rib cage. The regulation of chest wall volume during exercise in asthmatics is different than in healthy, suggesting a different use of respiratory muscles to cope with increased resistance. ![Figure][1] [1]: pending:yes