Short term variability in FEV1 and bronchodilator responsiveness in patients with obstructive ventilatory defects.

Abstract

Short term variability in FEV1 and responsiveness to inhaled bronchodilator were measured in 150 patients with obstructive ventilatory defects. The range of initial FEV1 was 0 5-4 71 and the natural variability over a 20 minute period when expressed in absolute terms was similar over the entire range, and differed insignificantly from that found in normal subjects. The increase in FEV1 and vital capacity (VC) required to exclude natural variability with 95% confidence in these patients was 160 ml and 330 ml respectively. Natural variability when expressed in percentage terms was negatively correlated with the level of FEV1 recorded. The analysis of changes in FEV1 and VC after administration of bronchodilator used absolute and percentage criteria for response.

Effects of formoterol, salmeterol or oxitropium bromide on airway responses to salbutamol in COPD

“…Nevertheless, we underline that our study had an 80% power of detecting a difference in FEV1 of at least 0.11 L between treatments. The absolute increase in FEV1 necessary to distinguish, with 95% confidence, between natural variability and a response to bronchodilator in patients with COPD is 0.16 L [11].…”

Interpretative strategies for lung function tests

“…The per cent change in FVC and FEV1 after bronchodilator administration in general population studies [108][109][110] and patient populations [101,[111][112][113] are summarised in table 8. Studies show a tendency for the calculated bronchodilator response to increase with decreasing baseline VC or FEV1, regardless of whether the response was considered as an absolute change or as a per cent of the initial value.…”

A hospital-based case-control study of quality of life in older asthmatics

“…In order to further substantiate the label of asthma, patients' data were analysed only if they fulfilled at least one of the following criteria: 1) airways reversibility (>15% improvement in forced expiratory volume in one second (FEV1) 20 min after the administration of 5 mg salbutamol and 0.5 mg ipratropium bromide via a nebulizer, with a minimum increase in FEV1 of 160 mL, as described by TWEEDALE et al [9]); 2) minimal smoking history (a smoking history of <10 pack-years); 3) longstanding history (history of asthma of ≥40 yrs); 4) absence of airflow obstruction (postnebulizer FEV1 >65% predicted, i.e. within 2 SD of expected values in this age range [10]).…”