Comparison of a New Desktop Spirometer (Spirospec) with a Laboratory Spirometer in a Respiratory Out-Patient Clinic

BACKGROUND: The performance of spirometers is often evaluated under ideal conditions with computergenerated waveforms or in vivo testing with healthy subjects. Real-life conditions are less ideal because of comorbidities, age of the subjects, and a variety of air flow limitations. Evaluation of new spirometry equipment can also be performed under these less favorable conditions. The Spirospec is a new desktop spirometer that is commercially available, but its accuracy has not been evaluated in a clinical setting.

OBJECTIVE: Test the Spirospec with subjects with normal and pathologic pulmonary function.

METHODS: A group of 45 patients (mean age 38.4 years, 27 male) booked for evaluation in the pulmonary function laboratory of a tertiary care university hospital were tested with both a Spirospec and a standard Jaeger Masterlab 4.0 spirometer, according to the guidelines of the American Thoracic Society. Three subgroups (normal spirometry, obstructive air flow limitation, and restrictive air flow limitation) of 15 consecutive subjects each underwent spirometry.

RESULTS: Pulmonary function measurements from the Spirospec correlated closely (r=0.95–0.99) with those from the Masterlab 4.0, showing good limits of agreement and differences between the 2 devices: forced vital capacity 0.03 L, forced expiratory volume in the first second (FEV₁) −0.01 L, peak expiratory flow −0.41 L/s, peak inspiratory flow 0.43 L/s, forced expiratory flow at 50% of total lung capacity 0.13 L/s, and forced expiratory flow at 75% of total lung capacity 0.12 L/s. With the exception of forced vital capacity and FEV₁, these differences were statistically significant (p < 0.05).

CONCLUSION: The Spirospec is comparable to the Masterlab 4.0, with high accuracy for FEV₁ and forced vital capacity and clinically acceptable differences in the measured flow variables.