Measuring lung mechanics in patients with <scp>COPD</scp> using the handheld portable rapid expiratory occlusion monitor (<scp>REOM</scp>): A cross‐sectional study

While conventional spirometry is associated with strenuous "forced" maximal respiratory maneuvers and infection control implications, oscillometry is not associated with these issues. However, portability, convenience of use, and interpretation remain common limitations to both techniques. This study tested the concordance and agreement between resistance measurements obtained from the handheld portable REOM device (R_eo-f, R_eo-s) with those from conventional oscillometry (R₁₉, R₅) in PFT-confirmed "mild" (GOLD 1) and "very severe" (GOLD 4) COPD. Unadjusted and adjusted concordance (Spearman correlation) and agreement (Bland-Altman tests) served as co-primary outcomes. Discrimination between GOLD 1 and 4 COPD (Wilcoxon rank sum test, Support Vector Machine (SVM) classifier) and patient user experience (System Utility Scale (SUS), Participant Satisfaction Survey (PSS)) served as secondary outcomes. In 17 participants (GOLD 1 n = 9, GOLD 4 n = 8), adjusted R₅-R_eo-s (0.95 [0.81, 0.98]) and R₁₉-R_eo-f (0.93 [0.79, 0.99]) correlations were very strong, as was agreement (mean differences: -0.07, 0.08, respectively). Statistically significant between-group differences were observed for all four resistance parameters. R_eo-s in particular exhibited perfect discrimination between GOLD 1 and 4 disease, with some minor misclassification by R_eo-f, R₅ (n = 1 each) and R₁₉ (n = 4). User experience scores were excellent. These results support the capacity for REOM as a novel, complementary diagnostic device in COPD.