The launching of cheap, pocket-sized spirometers, with data storage capability, has made patient- .... patients had to continue registration beyond the end.
(1996) 90, 131-138
Patient-administered sequential spirometry in healthy volunteers and patients with a,-antitrypsin deficiency F. MADSEN?,
C. S. ULRIK*,
A. DIRKSEN *, K. K. HANSEN*, K. VISKUM*
of Pulmonary Medicine, RHIMA-Centre,
N. H. NIELSEN*, AND A. KOK-JENSEN*
Bispebjerg Hospital, and TDepartment of Pulmonary Rigshospitalet, Copenhagen, Denmark
The launching of cheap, pocket-sized spirometers, with data storage capability, has made patient-administered sequential spirometry (PASS) an attractive method of monitoring ventilatory capacity. At present, little information is available on the quality of PASS, compared to laboratory spirometry. The aim of this study was to investigate whether patients could perform PASS without loss of reliability and reproducibility as compared with traditional laboratory spirometry. Ten healthy volunteers performed spirometry for 1 month and 10 emphysematous patients with aiantitrypsin 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 for calibration and a 3.8% annual drift in volume registration was noted. This drift was largest for the first year. After training, all patients were able to perform unsupervised spirometry, producing technically correct forced expiratory curves. Reproducibility of FEV, and FVC obtained by PASS was found to be as good as for laboratory spirometry. After adjustment for the diurnal variation, the residual variation of FEV, was 2.5% (range 164.2%) for healthy volunteers and 5.6% (range 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 compared to laboratory spirometry.
Introduction Dynamic spirometry of acceptable quality has been restricted to laboratories until recently. With the introduction of small, pocket-sized spirometers, patient-administered sequential spirometry (PASS) has become an interesting alternative to laboratory spirometry. However, before PASS is used for clinical evaluation of patients and research, both the equipment and methods should be standardized. A tremendous amount of work has been put into the standardization of laboratory spirometry by individual researchers as well as by national and international scientific societies (l-l 1). This work has Received
12 June 1995 and accepted
TAutha to whom correspondence Centre Rigshospitalet, Sektion Copenhagen N, Denmark. 0954-6111/96/030131+08
14 June 1995.
should be addressed at: RHIMA7551, Tagensvej 20, DK-2200
resulted in detailed specifications for equipment and testing procedure leading to highly accurate and reproducible results. At present, it seems unlikely that equipment and testing protocols for laboratory spirometry will improve much in the near future. In contrast to laboratory spirometry, knowledge about the possibilities and limitations of PASS is just emerging. Patient-administered sequential spirometry has been successfully used in the monitoring of lung transplants (12,13), but no information on the reliability of PASS was available until recently (14). As part of a European controlled clinical trial of a,-antitrypsin augmentation therapy (15) it has been essential to initiate a standardization process for PASS. In 1989, when this study was designed, very little information was available on patient performance during unsupervised forced expiratory manoeuvres (16) and furthermore the stability of the 0
1996 W. B. Saunders
F Madsen et al.
I Subject characteristicsand pulmonary function variables
Age (years) Height (m) FEV, (1) FVC (1) FEV,% pred. (“!)
40.8 1.81 4.31 519 108.0
9.48 0.10 0.64 0.87 12.1
41.1 1.72 1.66 4.50 51.5
10.0 0.06 0.48 1.35 11.4
pocket-sized spirometers was virtually unknown. Therefore, it was essential that both methods and spirometers used for PASS were tested scientifically, as has been the case for commercial spirometers used in laboratories (17). Today the main interest on PASS equipment focuses on hand-held, pocket-sized spirometers, but it has only recently become possible to collect data which makes a judgement of the quality of the expiratory manoeuvre possible. Before accepting results obtained with a pocketsized spirometer, documentation of the patients’ ability to perform correct forced expiratory manoeuvres unsupervised, as well as data on short- and long-term stability of the equipment, is needed. In 1991, no pocket-sized spirometers met these demands (12, 13, 18, 19). Consequently, instead of using this type of spirometer in a long-term clinical trial (15), a well-tried, direct writing, wedge spirometer was used in this study in order to assure the quality of PASS, and thereby fulfil Good Clinical Practice (GCP) criteria on data documentation (20). The aim of the present study was to investigate whether PASS could be performed unsupervised: (1) with correct expiratory technique; and (2) without loss of reliability and reproducibility compared to laboratory spirometry. Material STUDY
and Methods POPULATION
The study population consisted of 10 healthy subjects and 10 patients with severe a,-antitrypsin deficiency (phenotype PiZ) and moderate emphysema [35%