Reproducibility of forced inspiratory and expiratory volumes after bronchodilation in patients with COPD or asthma.

The aim of the present study was to assess the reproducibility of changes in forced inspiratory volumes after bronchodilator inhalation. Thirteen patients with chronic obstructive pulmonary disease (COPD) (FEV1, 32–75%pred) and 10 patients with asthma (FEV1, 43–75%pred) inhaled either 200*μ g fenoterol or 200*μ g oxitropium bromide or placebo, each of them on three occasions, on nine different days in a randomised, cross-over, double-blind fashion. Forced expiratory (FEV1) and inspiratory (FIV1) volumes were measured before and 30*min after inhalation. In patients with COPD, the increase in FEV1 (coefficient of variation) was 221*ml (43%) after fenoterol and 235*ml (33%) after oxitropium; changes in FIV1 were 301*ml (45%) and 360*ml (29%). In patients with asthma, FEV1 improved by 618*ml (26%) and 482*ml (25%), FIV1 by 553*ml (41%) and 475*ml (23%). In less severe COPD or asthma, the reduction in dyspnoea was associated with the improvements in both FIV1 and FEV1, but in severe COPD with the improvement in FIV1 only. The data demonstrate that, at least in terms of relative changes, the reproducibility of bronchodilator responses in terms of FIV1 is similar to that of FEV1 and they underline the assertion of FIV1 being a sensible parameter particularly in severe COPD.