Comparing a new device to measure lung volumes with three traditional methods in individuals with different lung conditions

BackgroundLung volumes can be measured by body plethysmography (BP), by inert gas dilution during a single-breath or multiple breaths and by radiographic methods based on chest roentgenogram or CT scanning. Our objective was to analyze the concordance between several methods including a new instrument in a variety of pulmonary conditions. MethodsWe recruited four groups of adult volunteers at the COPD and Tobacco Clinic of a respiratory referral hospital: patients with lung bullae, with obstructive lung diseases, with restrictive lung diseases and healthy controls; all subjects underwent lung volume measurements according to ATS/ERS standards in random order with each method and then CT scanning. Differences among groups were estimated by Kruskal-Wallis tests. Concordance correlation coefficients (CCC) and Bland-Altman plots were performed. ResultsSixty-two patients were studied including 15 with lung bullae, 14 with obstructive lung diseases, 12 with restrictive lung disease and 21 healthy subjects. Highest concordance was obtained between BP and CT scanning (CCC 0.95, mean difference -0.35 L) and the lowest, with TLC-DLCOsb (CCC 0.65, difference - 1.05 L). TLC measured by BP had a moderate concordance with Minibox (CCC=0.91, mean difference -0.19 L). Minibox, on the other hand had the lowest intratest repeatibility (2.7%) of all tested methods. ConclusionsLung volumes measured by BP and CT had a substantial concordance in the scenario of varied pulmonary conditions including lung bullae, restrictive and obstructive diseases. The new minibox device, had low intratest variability, and was easy to perform, with a reasonable concordance with BP.