S99 COMPARISON OF THE MEASUREMENT OF BRONCHODILATOR RESPONSE IN PATIENTS WITH ASTHMA AND HEALTHY VOLUNTEERS USING SPIROMETRY AND IMPULSE OSCILLOMETRY

¹J. H. Ward, ¹A. Nair, ²B. J. Lipworth. ¹Ninewells Hospital and Medical School, Dundee, UK, ²Asthma and Allergy Research Group, Ninewells Hospital and Medical School, Dundee, UK

Introduction Reversible airflow obstruction is often used as a criterion to support a clinical diagnosis of asthma. Bronchodilator reversibility is conventionally measured by forced expiratory spirometric manoeuvres, but is effort dependent and requires patient cooperation. Impulse oscillometry (IOS) is an effort-independent and patient-friendly lung function technique which appears to be an attractive alternative, but there are limited data correlating the bronchodilator response using the two techniques in adults with asthma and healthy volunteers.

Objectives To correlate clinical measurements performed by spirometry and IOS in response to administration of a bronchodilator in adults with asthma and healthy volunteers.

Methods The study was a prospective audit of ptients with asthma and healthy volunteers attending routine screening at a research unit in a university teaching hospital. Reversibility testing was carried out using standardised ATS/ERS criteria after administering 400 μg of sallbutamol via a valved spacer device. Spirometric (forced expiratory volume in 1 s (FEV₁)) and IOS measurements (R5, R20, X5) were as per ERS/ATS guidelines.

Results Ninety-five patients with asthma and 61 healthy volunteers underwent screening. The mean percentage predicted (SEM) baseline prebronchodilator FEV₁ was 83.99 (2.23) for those with asthma and 99.25 (1.72) for healthy volunteers. Baseline percentage predicted oscillometry indices in the group with asthma were 162.22 (7.5) for R5; 154.73 (4.71) for R20; and 441.72 (173.86) for X5. In the healthy volunteers this was 111.01 (3.96) for R5; 127.75 (4.12) for R20; and −229.80 (125.75) for X5.R5 was the only impulse oscillometry measure that showed correlation with spirometric indices (FEV₁). The mean percentage predicted (SEM) postbronchodilator change in FEV₁ and R5 in the group …