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      Evaluation of Exertional Ventilatory Parameters Using Oscillometry in COPD

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          Oscillometry is a tool to measure respiratory impedance that requires minimal patients’ effort. In patients with chronic obstructive pulmonary disease (COPD), the correlation of respiratory impedance at rest with exertional ventilatory parameters, including exercise tolerance, has scarcely been reported. In addition, the utility of oscillometric parameters might differ between the inspiratory and expiratory phases due to airflow obstruction during expiration, but the hypothesis had not been validated. The aim of the present study was to investigate whether oscillometric parameters are associated with exertional ventilatory parameters in patients with COPD.


          Fifty-five subjects with COPD who attended clinics at the National Hospital Organization Osaka Toneyama Medical Center performed spirometry, oscillometry, and cardiopulmonary exercise testing (CPET) within 2 weeks. The correlations between parameters of spirometry, oscillometry, and CPET were analyzed using Spearman’s rank correlation coefficient, univariate, and multivariate analyses.


          Respiratory reactance had better correlations with the CPET parameters than respiratory resistance. Moreover, inspiratory reactance at rest correlated with the CPET parameters stronger than expiratory reactance. In particular, inspiratory resonant frequency (Fres-ins) correlated with peak oxygen uptake (r S=−0.549, p<0.01) and dead space to tidal volume ratio at peak exercise (r S=0.677, p<0.01) and the best predicted expiratory tidal volume (V T ex) at peak exercise of all the oscillometric parameters (r S=−0.679, p<0.01). However, the correlation between Fres-ins and V T ex at peak exercise became weak in subjects with severe and very severe COPD during exercise.


          Measurement of respiratory reactance is useful for the effortless evaluation of not only exertional ventilatory parameters but exercise tolerance in patients with COPD. The correlation of respiratory impedance with exertional ventilatory parameters can become weak in patients with advanced COPD; thus, the measurement of oscillometry might not be appropriate for evaluating exertional ventilatory parameters of patients with advanced COPD.

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          Most cited references 24

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          The forced oscillation technique in clinical practice: methodology, recommendations and future developments

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            Detection of expiratory flow limitation in COPD using the forced oscillation technique.

            Expiratory flow limitation (EFL) during tidal breathing is a major determinant of dynamic hyperinflation and exercise limitation in chronic obstructive pulmonary disease (COPD). Current methods of detecting this are either invasive or unsuited to following changes breath-by-breath. It was hypothesised that tidal flow limitation would substantially reduce the total respiratory system reactance (Xrs) during expiration, and that this reduction could be used to reliably detect if EFL was present. To test this, 5-Hz forced oscillations were applied at the mouth in seven healthy subjects and 15 COPD patients (mean +/- sD forced expiratory volume in one second was 36.8 +/- 11.5% predicted) during quiet breathing. COPD breaths were analysed (n=206) and classified as flow-limited if flow decreased as alveolar pressure increased, indeterminate if flow decreased at constant alveolar pressure, or nonflow-limited. Of these, 85 breaths were flow-limited, 80 were not and 41 were indeterminate. Among other indices, mean inspiratory minus mean expiratory Xrs (deltaXrs) and minimum expiratory Xrs (Xexp,min) identified flow-limited breaths with 100% specificity and sensitivity using a threshold between 2.53-3.12 cmH2O x s x L(-1) (deltaXrs) and -7.38- -6.76 cmH2O x s x L(-1) (Xexp,min) representing 6.0% and 3.9% of the total range of values respectively. No flow-limited breaths were seen in the normal subjects by either method. Within-breath respiratory system reactance provides an accurate, reliable and noninvasive technique to detect expiratory flow limitation in patients with chronic obstructive pulmonary disease.
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              Impulse oscillometry: interpretation and practical applications.

              Simple spirometry and body plethysmography have been routinely used in children aged > 5 years. New techniques based on physiologic concepts that were first described almost 50 years ago are emerging in research and in clinical practice for measuring pulmonary function in children. These techniques have led to an increased understanding of the pediatric lung and respiratory mechanics. Impulse oscillometry (IOS), a simple, noninvasive method using the forced oscillation technique, requires minimal patient cooperation and is suitable for use in both children and adults. This method can be used to assess obstruction in the large and small peripheral airways and has been used to measure bronchodilator response and bronchoprovocation testing. New data suggest that IOS may be useful in predicting loss of asthma control in the pediatric population. This article reviews the clinical applications of IOS, with an emphasis on the pediatric setting, and discusses appropriate coding practices for the clinician.

                Author and article information

                Int J Chron Obstruct Pulmon Dis
                Int J Chron Obstruct Pulmon Dis
                International Journal of Chronic Obstructive Pulmonary Disease
                13 July 2020
                : 15
                : 1697-1711
                [1 ]Department of Respiratory Medicine, National Hospital Organization Osaka Toneyama Medical Center , Osaka, Japan
                Author notes
                Correspondence: Keisuke Miki Department of Respiratory Medicine, National Hospital Organization Osaka Toneyama Medical Center , 5-1-1 Toneyama, Toyonaka, Osaka560-8552, JapanTel +81-6-6853-2001Fax +81-6-6853-3127 Email
                © 2020 Yamamoto et al.

                This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License ( By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms (

                Page count
                Figures: 4, Tables: 7, References: 37, Pages: 15
                Funded by: no specific funding for the present study
                The authors received no specific funding for the present study.
                Original Research


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