Comparison of the measurement of lung volumes with two different plethysmography techniques in a real-world environment

<bold>Introduction:</bold> The measurement of total lung volumes is essential to complement spirometry. However, plethysmography booths are expensive and cumbersome. The use of portable plethysmography equipment has recently become widespread (MiniBox ®). Although TLC measurements were validated against cabin measurements in some studies designed for this purpose, they should demonstrate reproducibility in the real daily life of a pulmonary function laboratory. <bold>Aim:</bold> To compare the results between both equipment in healthy adults. <bold>Material & Methods:</bold> 91 participants (59.3% female) were recruited from a single center (Mexico City). Measures by conventional plethysmography were compared with the MiniBox®. We performed it according to current ATS/ERS standards and the manufacturer's instructions by pulmonologists trained in respiratory physiology. To evaluate the degree of agreement, the mean of differences, and the 95% limits of agreement between volume measurements, we used the concordance correlation coefficient (CCC) and Bland–Altman plot. <bold>Results:</bold> The median values (IQR) of age, weight, and height were 43 (25), 67 (14), 162 (11). Contrary to the previously published works, there was a poor correlation between equipment and the main variables used for lung volume interpretation (Table 1). Our work included a significant number of healthy patients compared with others. Table 1. Volume measures of study subjects. <table-wrap><object-id>erj;64/suppl_68/PA2599/TB1</object-id><object-id>T1</object-id><object-id>TB1</object-id><table><colgroup><col></col><col></col><col></col><col></col></colgroup><tbody><tr><td></td><td>MiniBox</td><td>Plethysmography</td><td>p value</td></tr><tr><td>ITGV or FRC</td><td>2.45 (1.07)</td><td>2.96 (1.23)</td><td>0.0006</td></tr><tr><td>RV</td><td>1.26 (0.53)</td><td>1.8 (0.7)</td><td>0.0000</td></tr><tr><td>VC</td><td>3.98 (1.4)</td><td>3.94 (1.28)</td><td>0.0156</td></tr><tr><td>IC</td><td>2.7 (0.97)</td><td>2.78 (0.91)</td><td>0.0242</td></tr><tr><td>ERV</td><td>1.25 (0.87)</td><td>1 (0.79)</td><td>0.0002</td></tr><tr><td>TLC</td><td>5.29 (1.4)</td><td>5.71 (1.73)</td><td>0.0000</td></tr></tbody></table></table-wrap> Wilcoxon signed ranks test