PATIENT-ADMINISTERED SEQUENTIAL SPIROMETRY IN HEALTHY-VOLUNTEERS AND PATIENTS WITH ALPHA(1)-ANTITRYPSIN DEFICIENCY

The launching of cheap, pocket-sized spirometers, with data storage ca pability, has made patient-administered sequential spirometry (PASS) a n attractive method of monitoring ventilatory capacity. At present, li ttle information is available on the quality of PASS, compared to labo ratory spirometry. The aim of this study was to investigate whether pa tients could perform PASS without loss of reliability and reproducibil ity as compared with traditional laboratory spirometry. Ten healthy vo lunteers performed spirometry for 1 month and 10 emphysematous patient s with alpha(1)-antitrypsin deficiency (type PiZ) performed spirometry twice daily for up to 2 yr. To fulfil Good Clinical Practice criteria on full data documentation, a traditional direct recording spirometer , the Vitalograph R-model, was used. A decompression device was used f or calibration and a 3.8% annual drift in volume registration was note d. This drift was largest for the first year. After training, all pati ents were able to perform unsupervised spirometry, producing technical ly correct forced expiratory curves. Reproducibility of FEV(1) and FVC obtained by PASS was found to be as good as for laboratory spirometry . After adjustment for the diurnal variation, the residual variation o f FEV(1) was 2.5% (range 1.6-4.2%) for healthy volunteers and 5.6% (ra nge 4.2-7.7%) for emphysematous patients. Forced vital capacity showed the same pattern. In conclusion, PASS is possible in highly motivated individuals without loss of reliability and reproducibility when comp ared to laboratory spirometry.