The Validity And Reproducibility Of A Portable Spirometer Based On Differential Pressure Sensor

ObjectiveTo assess the validity of a portable spirometer which was made in china，comparison against an diagnostic spirometer(Medisoft BodyBox S5500，Belgium). Andassess the reproducibility of this spirometer.MethodsIn the validity study, there were45patients（mean age52.8±18.67years，27male）were random selected to entry this study, all of the subjects tested the lung ventilationfunction with both a portable spirometer and Medisoft BodyBox S5500, Thencontrasted the result of the FVC、FEV1、FEV1/FVC、PEF、MEF75、MEF50、MEF25which obtained from the both spirometers. In the reproducibility study, there were22healthy volunteers (mean age32.3±11.31years old,20males) participated in the study,Lung ventilation function was performed in22healthy volunteers by two observers onthe same day and repeated by the first observer after24h, then analysis theinter-observer and day-to-day reproducibility.ResultsIn the validity study, pulmonary function measurements from the portablespirometer correlated closely with those from the Medisoft BodyBox, the r of thoseparameters are0.97、0.977、0.853、0.929、0.929、0.868、0.857respectively for FVC、FEV1、FEV1/FVC、PEF、MEF75、MEF50、MEF25. Bland-Altman chart showed good limits of agreement between the two apparatus，only two or three date were outside ofthe limits of agreement. The differences were statistically significant for FVC、FEV1、PEF、MEF75which from the both apparatus (P<0.05). In the reproducibility study, Theinter-observer and day-to-day intra-class correlation coefficients all higher than0.75,there were no significant difference between each other. Bland-Altman chart showedgood limits of agreement between inter-observer and day-to-day, only one or two datewere outside of the limits of agreement.ConclusionPulmonary function measurements from the portable spirometer correlated closelywith those from the Medisoft BodyBox, the reproducibility study showed a goodinter-observer and day-to-day reproducibility. Therefore, the portable spirometer withgood repeatability and validity, can be used for testing lung function in clinical.