An Evaluation of the P.K. Morgan Pocket Spirometer

Abstract

The P. K. Morgan pocket spirometer, which has recently become available in the United States, is small, portable, relatively inexpensive, and measures forced vital capacity (FVC) and the forced exhaled volume in 1 second (FEV₁). We conducted this study to evaluate the accuracy of the FVC and FEV₁ measurements by the P.K. Morgan spirometer. Methods: The flow signal used to evaluate the Morgan spirometer was produced by a Vent-Aid TTL Training Test Lung. The flow of air from the test lung was directed in series through the Morgan's volume transducer and into the bell of a 9-L Collins water-sealed spirometer. Results: The difference between Collins mean FVC and Morgan mean FVC was not significant (P = 0.17). The correlation coefficient for the relationship between Collins FVC and Morgan FVC was 0.996. American Thoracic Society (ATS) standards for accuracy were met by 56% of the FVC volumes measured by the Morgan. The difference between Collins mean FEV₁ and Morgan mean FEV₁ was clinically small but statistically significant (P = 0.01). The correlation coefficient for the relationship between Collins FEV₁ and Morgan FEV₁ was 0.999. ATS standards for accuracy were met by 87% of the FEV₁ volumes measured by the Morgan. Conclusion: The overall accuracy of the Morgan spirometer is adequate for bedside screening, but its accuracy is not sufficient to allow it to be used for diagnostic spirometry in place of more accurate pulmonary function equipment.