Bronchodilation test in COPD: effect of inspiratory manoeuvre preceding forced expiration

The effects of an inspiratory manoeuvre preceding forced expiration on functional tests performed under routine conditions before and after inhalation of a bronchodilator drug (salbutamol) were assessed on 150 consecutive chronic obstructive pulmonary disease outpatients. The patients performed forced vital capacity manoeuvres either immediately after a rapid inspiration (manoeuvre no. 1) or after a slow inspiration with a 4-6 s pause (manoeuvre no. 2). Under baseline conditions, forced expiratory volume in one second (FEV1) values were 8% (% control) larger with manoeuvre no. 1 than no. 2. FEV1 values increased with salbutamol administration by approximately 8% and were, on average, still 7% larger with manoeuvre no. 1 than no. 2. The incidence of reversibility, assessed according to American Thoracic Society criteria, was 76% when manoeuvre no. 2 was selected to represent baseline conditions and manoeuvre no. 1 was chosen to represent the effects of bronchodilator administration, whereas the lowest incidence (2%) was found when manoeuvre no. 1 was selected to represent baseline conditions and manoeuvre no. 2 was chosen to represent the effects of bronchodilator administration. These results indicate that the time dependence of the forced vital capacity manoeuvre has an important impact on the assessment of routine lung function in a clinical setting and supports the notion that the time course of the inspiration preceding the forced vital capacity manoeuvre should be standardised.