Long-term change in reactance by forced oscillation technique correlates with FEV1 decline in moderate COPD patients

BackgroundForced Oscillation Technique (FOT) is an innovative tool to measure within-breath reactance at 5 Hz (ΔXrs5Hz) but its feasibility and utility in acute exacerbations of COPD (AECOPD) is understudied.MethodsA prospective observational study was conducted in 82 COPD patients admitted due to AECOPD. FOT indices were measured and the association between these indices and spirometry, peak inspiratory flow rate, blood inflammatory biomarkers and patient-reported outcomes including assessment of dyspnoea, quality of life; anxiety and depression and frailty at admission and discharge were explored.ResultsAll patients were able to perform FOT in both sitting and supine position. The prevalence of expiratory flow limitation (EFL) in the upright position was 39% (32/82) and increased to 50% (41/82) in the supine position. EFL (measured by ΔXrs5Hz) and resistance at 5 Hz (Rrs5Hz) negatively correlated with FEV1; those with EFL had lower FEV1 (0.74±0.30 versus 0.94±0.36 L, p=0.01) and FVC (1.7 ±0.55 versus 2.1 ±0.63 L, p= 0.009) and higher BMI [27 (21–36) versus 23 (19–26) kg/m2, p=0.03] compared to those without EFL. During recovery from AECOPD, changes in EFL was observed in association with improvement in breathlessness.ConclusionFOT was easily used to detect EFL during hospitalisation due to AECOPD. The prevalence of EFL increased when patients moved from a seated to a supine position and EFL was negatively correlated with airflow limitation. Improvements in EFL were associated with a reduction in breathlessness. FOT is of potential clinical value by providing a non-invasive, objective, and effort-independent technique to measure lung function parameters during AECOPD requiring hospital admission.

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Repeated measurement of respiratory function and bronchoconstriction in unanesthetized mice

Journal of Applied Physiology ◽

10.1152/jappl.1995.79.5.1711 ◽

1995 ◽

Vol 79 (5) ◽

pp. 1711-1716 ◽

Cited By ~ 24

Author(s):

E. M. Hessel ◽

A. Zwart ◽

E. Oostveen ◽

A. J. Van Oosterhout ◽

D. I. Blyth ◽

...

Keyword(s):

Respiratory Function ◽

Forced Oscillation ◽

The Body ◽

Forced Oscillation Technique ◽

Respiratory Resistance ◽

Transfer Impedance ◽

Flow Response ◽

Term Basis ◽

Spontaneously Breathing

A noninvasive forced oscillation technique was used to determine respiratory function in unanesthetized and spontaneously breathing mice. Pseudorandom noise pressure variations in a frequency range of 16–208 Hz were applied to the body surface, and the flow response was measured at the nose. From the pressure-flow relationship, respiratory transfer impedance was calculated. Study of intra-animal variability on a short- and a long-term basis revealed that the real part of respiratory transfer impedance was reproducible within 9%. The imaginary part appeared less reproducible (within 22%). Furthermore, bronchoconstrictive responses were investigated and analyzed by evaluation of respiratory resistance as measured at 16 Hz (Rrs16). During the first 15 min after ovalbumin challenge in ovalbumin-sensitized mice, Rrs16 was significantly increased [49 +/- 7% (SE)]. Inhalation of methacholine in untreated mice induced an increase in Rrs16 of 75 +/- 16% (SE). In saline-challenged animals, no significant changes were observed. This method enables evaluation of long-term respiratory function in mice and appeared to be a sensitive measure for bronchoconstriction.

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Annual change in forced oscillation technique correlates with FEV1 decline in patients with asthma, COPD, and asthma-COPD overlap

Journal of Allergy and Clinical Immunology ◽

10.1016/j.jaci.2019.12.578 ◽

2020 ◽

Vol 145 (2) ◽

pp. AB118

Author(s):

Yuko Tanaka ◽

Keita Hirai ◽

Hiromasa Nakayasu ◽

Kanami Tamura ◽

Toshihiro Masuda ◽

...

Keyword(s):

Forced Oscillation ◽

Forced Oscillation Technique ◽

Annual Change ◽

Fev1 Decline

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Forced oscillation technique (FOT) in the evaluation of COPD patients enrolled in Pulmonary Rehabilitation (PR)

10.1183/13993003.congress-2019.pa3417 ◽

2019 ◽

Author(s):

Isabella Romagnoli ◽

Barbara Lanini ◽

Elisa Chellini ◽

Claudia Mannini ◽

Barbara Binazzi ◽

...

Keyword(s):

Pulmonary Rehabilitation ◽

Forced Oscillation ◽

Forced Oscillation Technique ◽

Copd Patients

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Variability of within-breath reactance in COPD patients and its association with dyspnoea

European Respiratory Journal ◽

10.1183/09031936.00051214 ◽

2014 ◽

Vol 45 (3) ◽

pp. 625-634 ◽

Cited By ~ 15

Author(s):

Bernt B. Aarli ◽

Peter M.A. Calverley ◽

Robert L. Jensen ◽

Tomas M.L. Eagan ◽

Per S. Bakke ◽

...

Keyword(s):

Continuous Measurement ◽

Medical Research Council ◽

Forced Oscillation ◽

Chronic Obstructive ◽

Forced Oscillation Technique ◽

Flow Limitation ◽

Oscillation System ◽

Expiratory Flow Limitation ◽

Obstructive Pulmonary Disease ◽

Copd Patients

The forced oscillation technique can identify expiratory flow limitation (EFL) when a large difference in inspiratory and expiratory reactance (ΔXrs) occurs. However, flow limitation can vary from breath to breath, and so we compared a multiple-breath ΔXrs approach to the traditional breath-by-breath assessment of EFL. We investigated the within- and between-day reproducibility and the factors that affect the size of ΔXrs when used as a continuous measurement over multiple breaths. In addition, we examined how multiple-breath ΔXrs relates to the sensation of breathlessness.425 moderate to very severe chronic obstructive pulmonary disease (COPD) patients and 229 controls were included. Spirometry and impedance measurements were performed on a MasterScope CT Impulse Oscillation System.Median ΔXrs approached zero in healthy controls with little variation between measurements. COPD patients generally had higher ΔXrs and higher variability. The COPD patients with ΔXrs >0.1 kPa·L−1·s−1 were prone to be more breathless and had a higher modified Medical Research Council dyspnoea scale score. In controls, the 95th percentile of ΔXrs was as low as 0.07 kPa·L−1·s−1.We describe a new method to assess EFL at a patient level and propose a cut-off, mean ΔXrs >0.1 kPa·L−1·s−1, as a way to identify COPD patients who are more likely to report dyspnoea.

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Vivid Imagers Are Better at Detecting Salient Changes

Journal of Individual Differences ◽

10.1027/1614-0001.27.4.218 ◽

2006 ◽

Vol 27 (4) ◽

pp. 218-228 ◽

Cited By ~ 13

Author(s):

Paul Rodway ◽

Karen Gillies ◽

Astrid Schepman

Keyword(s):

Individual Differences ◽

Change Detection ◽

Visual Imagery ◽

Detection Task ◽

Level Of Detail ◽

Detection Accuracy ◽

Change Detection Task ◽

Term Change ◽

High Level

This study examined whether individual differences in the vividness of visual imagery influenced performance on a novel long-term change detection task. Participants were presented with a sequence of pictures, with each picture and its title displayed for 17 s, and then presented with changed or unchanged versions of those pictures and asked to detect whether the picture had been changed. Cuing the retrieval of the picture's image, by presenting the picture's title before the arrival of the changed picture, facilitated change detection accuracy. This suggests that the retrieval of the picture's representation immunizes it against overwriting by the arrival of the changed picture. The high and low vividness participants did not differ in overall levels of change detection accuracy. However, in replication of Gur and Hilgard (1975) , high vividness participants were significantly more accurate at detecting salient changes to pictures compared to low vividness participants. The results suggest that vivid images are not characterised by a high level of detail and that vivid imagery enhances memory for the salient aspects of a scene but not all of the details of a scene. Possible causes of this difference, and how they may lead to an understanding of individual differences in change detection, are considered.

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