Comparative evaluation of expiratory airflow limitation between patients with COPD and BE using IOS

Daniele Oliveira Dos Santos,Larissa Perossi,Mayara Holtz,Jéssica Perossi,Ada Clarice Gastaldi,Ricardo Grassi Moroli,José Antônio Baddini-Martinez,Letícia Helena De Souza Simoni

doi:10.1038/s41598-021-84028-9

Daniele Oliveira Dos Santos, Larissa Perossi + Show 6 more

Open Access

https://doi.org/10.1038/s41598-021-84028-9

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Abstract

Impulse oscillometry (IOS) allows evaluation of the compartmentalized resistance and reactance of the respiratory system, distinguishing central and peripheral obstruction. The IOS measurements are getting attention in the diagnosis and differentiation of chronic respiratory diseases. However, no data are available in the literature to differentiate between COPD and BE using IOS parameters. We aimed to evaluate the feasibility of IOS in the diagnosis of bronchiectasis non-cystic fibrosis (BE) in comparison to COPD. Whole breath, inspiration, expiration, and inspiratory-expiratory difference (Δ) were evaluated based on the IOS parameters: total resistance (R5), central airway resistance (R20), peripheral airway resistance (R5-R20), reactance (X5), reactance area (AX), and resonance frequency (Fres). Fifty-nine subjects (21 Healthy, 19 BE, and 19 COPD) participated in this study. It was observed a significant difference in the comparison of healthy and pulmonary disease groups (BE and COPD) for total breathing (R5-R20, X5, AX, and Fres), inspiratory phase (R5 and R5-R5), and expiratory phase (R5-R20 and X5). The comparison between BE and COPD groups showed significant difference in the expiratory phase for resistance at 5 and 20 Hz and, ΔR5 and ΔR20. The IOS evidenced an increase of R5, R20 and R5-R20 in patients with BE and COPD when compared to healthy subjects. Expiratory measures of IOS revealed increased airway resistance in COPD compared to BE patients who had similar FEV1 measured by spirometry, however, further studies are needed to confirm these differences.

Highlights

Abbreviations impulse oscillometry (IOS) Impulse oscillometry system chronic obstructive pulmonary disease (COPD) Chronic obstructive pulmonary disease R5 Total airway resistance R20 Central airway resistance R5-R20 Peripheral airway resistance X5 Respiratory reactance AX Reactance area FRES Resonant frequency bronchiectasis non-cystic fibrosis (BE) Bronchiectasis forced oscillation technique (FOT) Forced oscillation technique Zrs Respiratory impedance Xrs Respiratory resistance GOLD Global Initiative for Chronic Obstructive Lung Disease FEV1 Forced expiratory volume in first second Laboratory for Assessment of Respiratory System (LAR) Laboratory of Assessment Respiratory HC-FMRP Hospital of Clinics of Ribeirao Preto Medical School Hz Hertz
Comparison between Healthy and chronic pulmonary disease groups showed increased of R5 in the COPD group (p < 0.001), R5-20 in the BE (p = 0.01) and COPD (p = 0.001) groups; greater X5 negativity in the BE (p = 0.01) and COPD (p = 0.01) groups; increased AX in the BE (p = 0.01) and COPD (p = 0.01) groups, and increased frequency values (Fres) in the BE (p = 0.001) and COPD (p = 0.001) (Table 2)
Crisafulli and collaborators reported the progressive increase in small airway resistance related to the severity of the disease in individuals with COPD assessed by the IOS, these changes may be closely related by the symptoms[18]

Summary

Introduction

Abbreviations IOS Impulse oscillometry system COPD Chronic obstructive pulmonary disease R5 Total airway resistance R20 Central airway resistance R5-R20 Peripheral airway resistance X5 Respiratory reactance AX Reactance area FRES Resonant frequency BE Bronchiectasis FOT Forced oscillation technique Zrs Respiratory impedance Xrs Respiratory resistance GOLD Global Initiative for Chronic Obstructive Lung Disease FEV1 Forced expiratory volume in first second LAR Laboratory of Assessment Respiratory HC-FMRP Hospital of Clinics of Ribeirao Preto Medical School Hz Hertz. Spirometry is the gold standard pulmonary function test to evaluate airway obstruction in pulmonary d iseases[1,2]. The FOT is an easy-to-apply technique that provides reliable data on respiratory mechanics by measuring pressure and flow response to small forced oscillations[5]. The impulse oscillometry (IOS), a system developed from the FOT, measures respiratory impedance at multiple frequency ranges and allows functional evaluation of the airways by measuring the instantaneous response to pressure and flow to obtain the respiratory system impedance (Zrs), which included the respiratory resistance (Rrs) and respiratory reactance (Xrs) measured over a range of frequencies (usually from 3 to 35 Hz)[6]. The out-of-phase or imaginary part of Zrs, reactance (Xrs), is related to elastic and inertial properties of the respiratory system[5,7]

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