<qa>  What is the effect of inhaled corticosteroids?Human and animal studies have shown that inhaled corticosteroids ICS decrease airway blood flow . This effect is immediate within 30 minutes, transient lasting 90 minutes, and in animal studies independent of gene expression. In COPD patients, decrease in bronchial blood flow may also decrease mucosal edema, airway resistance and improve small airway function. If such an effect exists, then we should be able to measure improvements in airway conductance and reduce lung hyperinflation, which would have salutary effects on dyspnea and exercise endurance. 