Inspiratory resonant frequency of forced oscillation technique as a predictor of the composite physiologic index in interstitial lung disease
Introduction
Clinical application of the broadband frequency forced oscillation technique (FOT) has progressed recently and an increasing number of reports have examined its usefulness in the evaluation or management of obstructive lung diseases, including COPD or asthma (Paredi et al., 2010, Mori et al., 2011); however, very few investigators have examined respiratory impedance in interstitial lung disease (ILD). Van Noord et al. (1989) measured respiratory system resistance (Rrs) and reactance (Xrs) between 4 and 26 Hz by means of FOT in patients with ILD. They observed higher values of Rrs and decreases in Xrs, which were similar to those in moderate obstructive lung diseases. Mori et al. (2013) found that absolute values of Xrs were smaller in expiratory phases than in inspiratory phases in patients with ILD, which was the reverse change compared with that in patients with COPD. Sugiyama et al. (2013) showed a negative correlation between the differences between inspiratory and expiratory phases of Xrs at 5 Hz (ΔX5) and vital capacity or diffusing capacity.
The composite physiologic index (CPI), which is derived from forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and diffusing capacity for carbon monoxide (DLco), has been developed to predict the extent of fibrosis on high-resolution computed tomography (HRCT), adjusting for emphysema in patients with idiopathic pulmonary fibrosis (IPF) (Wells et al., 2003). A recent large cohort study showed that the CPI was superior to each pulmonary function test and a strong predictor of mortality in IPF (Schmidt et al., 2011). In contrast to spirometry or measurements of DLco, FOT is a method that is easy to perform in elderly patients or those with severe diseases. Forced oscillations are superimposed on tidal breathing, avoiding the need for any special breathing maneuver or noticeable interference with respiration. Furthermore, the relevance of FOT to pulmonary function tests, the CPI, and the degree of fibrosis in ILD is not fully understood. We hypothesized that FOT would predict independently the CPI, thereby becoming a useful biomarker in the management of ILD. In this cross-sectional study, we assessed the relationship between pulmonary function tests, forced oscillatory parameters, and the degree of fibrosis in 93 patients with ILD.
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Subjects
Ninety-three patients with ILD who attended outpatient clinics at Shizuoka General Hospital for routine check-ups between August 2011 and July 2013 were enrolled in this study. According to the classification of the ATS/ERS guidelines (Travis et al., 2013), the patients were diagnosed clinically and using HRCT with IPF in 28, non-IPF idiopathic interstitial pneumonias (Non-IPF IIPs) in 31, collagen vascular disease-associated interstitial pneumonia (CVD-IP) in 26, chronic hypersensitivity
Results
The clinical characteristics of the subjects are shown in Table 1. The characteristics of the ILD subgroups (IPF, Non-IPF IIPs, CVD-IP, and others) are also summarized in Supplemental Table 1. The patients with ILD were older and included more smokers and pack-years, lower values of FVC, FEV1, TLC, X5 (whole-breath, inspiratory, and expiratory), and ΔALX, and higher values of R5 (whole-breath, inspiratory, and expiratory), R20 (whole-breath), ΔX5, Fres, and ALX (whole-breath, inspiratory, and
Discussion
We assessed whether forced oscillatory parameters and fibrosis extent contributed independently to the CPI, which was derived from FEV1, FVC, and DLco in 93 patients with ILD. It was found that the CPI was independently predicted by inspiratory Fres, a forced oscillatory parameter, and fibrosis extent as measured by HRCT. These results suggest that FOT may be useful in the management of ILD.
Originally, the CPI was developed to predict the extent of fibrosis on HRCT and improve on previous
Funding
None.
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Cited by (28)
Window of opportunity for respiratory oscillometry: A review of recent research
2023, Respiratory Physiology and NeurobiologyRespiratory reactance in forced oscillation technique reflects disease stage and predicts lung physiology deterioration in idiopathic pulmonary fibrosis
2020, Respiratory Physiology and NeurobiologyCitation Excerpt :Conversely, Xrs was believed to be more important for the assessment of ILD pathophysiology, as the current study demonstrated. Fujii et al. (2015) found that Fres in the inspiratory phase correlated with the FVC, FEV1, DLCO, and fibrosis score in ILD. Sugiyama et al. (2013) reported that the presence of ILD was associated with ΔX5 and that ΔX5 was negatively correlated with VC and DLCO.
Forced Oscillation Technique and Small Airway Involvement in Chronic Hypersensitivity Pneumonitis
2019, Archivos de BronconeumologiaCitation Excerpt :Higher frequencies (>20 Hz) travel shorter distances, such as in the large airways, while lower frequencies (<15 Hz) travel deeper into the lung and reach the small airways.14 FOT has been used for the evaluation of asthma16,17 and chronic obstructive pulmonary disease (COPD)18–20; however, its role in the evaluation of small airway involvement in ILD is relatively incipient.21–26 Increased Rrs values at low frequencies have been found in sarcoidosis,24 silicosis27 and asbestosis,28 while reactance at 5 Hz (X5) values are usually low in patients with ILD.22
Longitudinal changes in pulmonary function and respiratory impedance of rheumatoid arthritis
2019, Respiratory Physiology and NeurobiologyCitation Excerpt :It is expected that FOT will be able to identify respiratory abnormalities that are not detectable by spirometric examinations (Oostveen et al., 2013; da Costa et al., 2014; Ito et al., 2017). Moreover, FOT has been used to characterize respiratory mechanics of interstitial lung disease and RA-related pulmonary diseases (Faria et al., 2012; Sugiyama et al., 2013; Fujii et al., 2015; Sokai et al., 2016). Several studies have investigated the longitudinal changes in pulmonary functions of RA (Linstow et al., 1994; Fuld et al., 2003; Zamora-Legoff et al., 2017), but the parameters of the long-term changes in Zrs of RA are not known.
Forced oscillation technique in veterans with preserved spirometry and chronic respiratory symptoms
2019, Respiratory Physiology and NeurobiologyCitation Excerpt :HRCT patterns of decreased attenuation and ground glass opacities are suggestive of emphysematous and interstitial changes, and these features are commonly associated with reductions in DLCO. In fact, Fujii et al. (2015) found that more negative reactance values were associated with worse DLCO in patients with interstitial lung disease, and no associations were observed with measures of resistance. That reduced DLCO was only observed among those with Abnormal AX in the present study appears to support this earlier work.
Responsiveness to bronchodilator procaterol in COPD as assessed by forced oscillation technique
2017, Respiratory Physiology and NeurobiologyCitation Excerpt :Measurement of respiratory system impedance (Zrs), respiratory resistance (Rrs), and reactance (Xrs), has been used to assess respiratory functions of pulmonary diseases, specifically COPD (Dellaca et al., 2004; Ito et al., 2005; Mishima, 2009; Kanda et al., 2010; Paredi et al., 2010; Ohishi et al., 2011; Hasegawa et al., 2015; Akita et al., 2016; Shirai and Kurosawa, 2016). FOT enables measurement of both inspiratory and expiratory parameters during tidal breathing (Cauberghs and Van De Woestijne, 1992; Peslin et al., 1992; Dellaca et al., 2004; Kanda et al., 2010; Paredi et al., 2010; Fujii et al., 2015; Sokai et al., 2016). Spirometry is a standard method to diagnose COPD and evaluate severity and response to medications of this disease (GOLD-2016, 2016).
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These authors contributed equally to this work.