A comparison of a new transtelephonic portable spirometer with a laboratory spirometer.

The Spirophone is a new, portable transtelephonic spirometer which records the slow and the forced expiratory vital capacity tests. Data can be transmitted via the telephone to a remote receiving centre, where a volume-time curve and the flow-volume curve are displayed on screen in real time. The aim of this study was to compare the newly developed transtelephonic spirometer, with a laboratory spirometer according to the American Thoracic Society (ATS) testing guidelines. Spirometry indices (slow vital capacity (SVC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), forced expiratory flow at 25, 50 and 75% of FVC (FEF25, FEF50, and FEF75, respectively)) were measured from the SVC and the FVC tests in 45 subjects (30 patients, 15 healthy volunteers) according to the ATS standards. The data obtained with the laboratory system were compared to those from the Spirophone. The Spirophone measurements of SVC, FVC, FEV1, PEF, FEF25, FEF50 and FEF75 correlated closely (r=0.91-0.98) to those from the laboratory system, whereas FEF25, FEF50, and FEF75 were significantly higher with the Spirophone. It is concluded that the Spirophone is comparable to the standard spirometry for home monitoring of slow vital capacity, forced vital capacity, forced expiratory volume in one second and peak expiratory flow. The validity of the manoeuvre can be assessed on screen in real time.