Poliszuk, Daniel

Abstract Rationale Oscillometry measures the mechanical properties of the respiratory system using the response to pressure signals superimposed on tidal breathing. The JaegerTM IOS device generates “pulse packets” of harmonic frequencies between 5 and 35 Hz in 5 Hz intervals, while the Resmon ProTM V3 FOT and Thorasys TremofloTM C-100 employ prime pseudorandom sine waveforms between 5-19 Hz and 5-37 Hz, respectively. Prior studies have raised concerns about harmonic distortion with the IOS technique, but a direct comparison of reproducibility using current devices has not been performed. Methods Healthy volunteers with normal spirometry performed weekly oscillometry following ERS technical standards using JaegerTM and ResmonTM or ThorasysTM oscillometers in random order for 10 consecutive weeks. Z scores were calculated using Berger and Oostveen normative equations. Means, pooled within-subject distributions and interquartile range, standard error (SEM), coefficient of variation (CVw%), absolute and relative minimal detectable change (MDC, MDC%), and between device and subject intraclass correlation coefficients (ICC) were calculated for R5, R10/R11, R20/R19, R5-R20/R5-R19, X5, AX, and Fres and compared. Results Fifteen participants completed 10 weekly measurement sessions with JaegerTM and ResmonTM and twelve with JaegerTM and ThorasysTM. One subject did not complete the ResmonTM analysis due to intolerance; another subject only completed three weeks of ThorasysTM prior to work assignment change. The majority (65%) were female with mean (SD) age of 37.7 (10.2) years and BMI 27 (5) kg/m2. Rrs reproducibility was excellent across devices (ICC > 0.89), with more variability for X5, AX, and Fres (ICC 0.66 - 0.93) and little difference between devices (Figure 1). Small, systematic increases in mean Rrs were seen with JaegerTM compared to ResmonTM (5-10%, p < 0.008) and TremofloTM (5-12%, p < 0.02), with higher mean AX vs ResmonTM (44%, p = 0.002) and lower Fres vs TremofloTM (19%, p = 0.02). There was high ICC (0.97-0.99) across ResmonTM and TremofloTM Rrs comparisons with minimal bias. Intra-subject reproducibility was similar between devices. MDC% was 22.7-39.4% for Rrs values, 52.7-70.8% for X5, and 131-142% for AX. Conclusions JaegerTM, ResmonTM, and ThorasysTM oscillometers performed similarly in healthy adults over 10 weeks, with small but systematic measurement differences seen with the JaegerTM device. Rrs and Fres values demonstrated the greatest reproducibility both within and between subjects. Reactance measurements had less between-device agreement and higher MDC. Rrs, X5, and AX changes of up to 40%, 70%, and 140% over time may be due to normal subject and measurement variation. This abstract is funded by: 2024 Pulmonary, Critical Care, and Sleep Medicine Schuen Family Innovation Award

Abstract Rationale Global Lung Function Initiative (GLI) Global spirometry reference equations were recently derived to offer a “race-neutral” interpretation option. The impact of transitioning from the race-specific GLI-2012 to the GLI Global reference equations is unknown. Objectives Describe the direction and magnitude of changes in predicted lung function measurements in a population of diverse race and ethnicity using GLI Global in place of GLI-2012 reference equations. Methods In this multicenter cross-sectional study using a large pulmonary function laboratory database, 109,447 spirometry tests were reanalyzed using GLI Global reference equations and compared with the existing GLI-2012 standard, stratified by self-reported race and ethnicity. Measurements and Main Results Mean FEV1 and FVC percent predicted increased in the White and Northeast Asian groups and decreased in the Black, Southeast Asian, and mixed/other race groups. The prevalence of obstruction increased by 9.7% in the White group, and prevalences of possible restriction increased by 51.1% and 37.1% in the Black and Southeast Asian groups, respectively. Using GLI Global in a population with equal representation of all five race and ethnicity groups altered the interpretation category for 10.2% of spirometry tests. Subjects who self-identified as Black were the only group with a relative increase in the frequency of abnormal spirometry test results (32.9%). Conclusions The use of GLI Global reference equations will significantly impact spirometry interpretation. Although GLI Global offers an innovative approach to transition from race-specific reference equations, it is important to recognize the continued need to place these data within an appropriate clinical context.

BACKGROUND: Residual volume (RV) is a derived lung compartment that correlates with air trapping in the context of air flow obstruction on spirometry. The significance of an isolated elevation in RV in the absence of other pulmonary function test (PFT) abnormalities is not well defined. We sought to assess the clinical and radiologic findings associated with isolated elevation in RV. METHODS: We searched our out-patient PFT database at Mayo Clinic (Rochester, Minnesota) from 2016–2018 for adult patients with isolated elevation in RV. We defined isolated elevation in RV as RV ≥ upper limit of normal or ≥ 130% predicted with normal total lung capacity (TLC), spirometry, and diffusion capacity of the lung for carbon monoxide (D LCO ). We then matched this high-RV group by age and sex to an equal number of individuals with normal RV, TLC, spirometry, and D LCO (normal-RV group). RESULTS: We identified 169 subjects with isolated elevation in RV on PFTs, with a median age of 73 y; 55.6% were female, and median body mass index was 26.8 (vs 29.8 in the normal-RV group). The median RV was 3.08 L (134% predicted, interquartile range [IQR] 130–141) in the high-RV group and 2.26 L (99% predicted, IQR 90–109) in the normal-RV group (P < .001). Subjects with high RV were more likely to have smoked (54% vs 40%, P = .01) and almost twice as likely to have a maximum voluntary ventilation < 30 times the FEV 1 (21% vs 12%, P = .02). Clinically, asthma (21% vs 11%, P = .01) and non–tuberculous mycobacterial lung infections (12% vs 2%, P = .001) were more prevalent in the high-RV group. On chest computed tomography, bronchiectasis (31% vs 15%, P = .008), bronchial thickening or mucus plugging (46% vs 22%, P < .001), and emphysema (13% vs 5%, P = .046) were more common in the high-RV group. CONCLUSIONS: Isolated elevation in RV on PFTs is a clinically relevant abnormality associated with airway-centered diseases.