Chronic obstructive bronchitis and emphysema (COPD) are pathophysiologically characterized by
inflammatory and structural changes in the lung. These changes lead to a reduction in elastic
recoil as well as reduction in lung parenchyma. As a consequence collapse of the small airway
occurs during expiration leading to expiratory flow limitation. In severe cases this flow
limitation occurs even during resting condition. This expiratory collapse is suspected to
mask changes in bronchial smooth muscle tone, especially if these changes in bronchial smooth
muscle tone are assessed using expiratory manoeuvres. This might leave the impression of
non-reversible airway obstruction und ineffectiveness of treatment with bronchodilators.
Several studies suggest that in patients with COPD symptomatic changes following application
of a bronchodilating compound do not correlate with changes in forced expiratory volumes. In
contrast inspiratory lung function parameters (especially forced inspiratory volume in one
second (FIV1)) is much more associated with symptomatic changes in patients with COPD.
Comparable effects were also detected regarding peak inspiratory flow (PIF) values.Changes in
inspiratory parameters following administration of a bronchodilator in patients with COPD and
asthma are reproducible. PIF can easily be measured by inspiratory peak flow meters. So far
no data exists on the usability of these devices following bronchodilation in patients with
COPD. Formoterol is a rapid acting bronchodilator, which has been proven save in asthma and
COPD