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Gunawardana, Shannon, Christopher Harris, and Anne Greenough. "Pseudorandom Noise Forced Oscillation Technique to Assess Lung Function in Prematurely Born Children." Children 9, no. 8 (August 22, 2022): 1267. http://dx.doi.org/10.3390/children9081267.
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The forced oscillation technique (FOT) is a non-volitional assessment that is used during tidal breathing. A variant of FOT uses a pseudorandom noise (PRN) signal which we postulated might have utility in assessing lung function in prematurely born children. We, therefore, undertook a systematic review to evaluate the evidence regarding PRN FOT. A comprehensive search of the literature was conducted by using the following databases: Medline, Embase, Web of Science and CINAHL. Observational studies, case series/reports and randomized-controlled trials were eligible for inclusion. Article abstracts and full texts were screened independently by two reviewers, with disagreements resolved by discussion or a third reviewer if necessary. Five studies were included (n = 587 preterm children). Three compared PRN FOT with spirometry, and two compare it to the interrupter technique. Most studies failed to report comprehensive methodology of the frequency spectra used to generate the PRN signal. There was evidence that poorer lung function, as assessed by PRN FOT, was associated with a greater burden of respiratory symptoms, but there was insufficient evidence to determine whether PRN FOT performed better than other lung-function tests. Detailed methodological documentation, in accordance with ERS guidance, is needed to assess the benefits of PRN FOT prior to routine clinical incorporation to assess prematurely born children.
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Ngo, Chuong, Karl Krüger, Thomas Vollmer, Stefan Winter, Bernhard Penzlin, Sylvia Lehmann, Steffen Leonhardt, and Berno Misgeld. "Effects of the nasal passage on forced oscillation lung function measurements." Biomedical Engineering / Biomedizinische Technik 62, no. 6 (November 27, 2017): 635–42. http://dx.doi.org/10.1515/bmt-2016-0158.
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AbstractThe forced oscillation technique (FOT) is a non-invasive pulmonary function test which is based on the measurement of respiratory impedance. Recently, promising results were obtained by the application of FOT on patients with respiratory failure and obstructive sleep apnea (OSA). By using a nasal mask instead of a mouthpiece, the influences of the nasal passage and upper shunt alter the measured mechanical impedance. In this paper, we investigated the effects of the nasal passage and mask on FOT measurements from eight healthy subjects. A method for flow correction has been developed, which contains a pressure-flow characteristics compensation of the undetermined flow leakage at the face-mask interface. Impedance calculation and parameter estimation were performed in the frequency domain using fast Fourier transform (FFT). Average nasal parameters were
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Ngo, Chuong, Sarah Spagnesi, Carlos Munoz, Sylvia Lehmann, Thomas Vollmer, Berno Misgeld, and Steffen Leonhardt. "Assessing regional lung mechanics by combining electrical impedance tomography and forced oscillation technique." Biomedical Engineering / Biomedizinische Technik 63, no. 6 (November 27, 2018): 673–81. http://dx.doi.org/10.1515/bmt-2016-0196.
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Abstract There is a lack of noninvasive pulmonary function tests which can assess regional information of the lungs. Electrical impedance tomography (EIT) is a radiation-free, non-invasive real-time imaging that provides regional information of ventilation volume regarding the measurement of electrical impedance distribution. Forced oscillation technique (FOT) is a pulmonary function test which is based on the measurement of respiratory mechanical impedance over a frequency range. In this article, we introduce a new measurement approach by combining FOT and EIT, named the oscillatory electrical impedance tomography (oEIT). Our oEIT measurement system consists of a valve-based FOT device, an EIT device, pressure and flow sensors, and a computer fusing the data streams. Measurements were performed on five healthy volunteers at the frequencies 3, 4, 5, 6, 7, 8, 10, 15, and 20 Hz. The measurements suggest that the combination of FOT and EIT is a promising approach. High frequency responses are visible in the derivative of the global impedance index $\Delta {Z_{{\text{eit}}}}(t,{f_{{\text{os}}}}).$ The oEIT signals consist of three main components: forced oscillation, spontaneous breathing, and heart activity. The amplitude of the oscillation component decreases with increasing frequency. The band-pass filtered oEIT signal might be a new tool in regional lung function diagnostics, since local responses to high frequency perturbation could be distinguished between different lung regions.
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Xu, Hui, Yi Gao, Yanqing Xie, Xiaolin Liang, and Jinping Zheng. "Bronchial provocation test measured by using the forced oscillation technique to assess airway responsiveness." Allergy and Asthma Proceedings 42, no. 5 (September 1, 2021): e127-e134. http://dx.doi.org/10.2500/aap.2021.42.210044.
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Background: The bronchial provocation test (BPT) performed by using the forced oscillation technique (FOT) is cooperated without forced expiratory effort. However, a comparison of the application value and safety of BPTs measured by using the FOT and the standardized dosimeter method is lacking, which limits its clinical practice. Objective: We aimed to analyze the diagnostic value and safety of the BPT as measured by the FOT in patients with asthma and in healthy subjects. Methods: This was a randomized cross-over clinical study. Airway responsiveness was measured by using the FOT and the aerosol provocation system (APS) dosimeter method in all the participants. The between-test interval was 24 hours. The diagnostic value and safety of the two tests were analyzed. Results: Asthma control status was assessed based on ACT scores, and patients with asthma (including 27 uncontrolled, 34 partially controlled, and 32 controlled) were collected, and 69 healthy subjects were recruited. Receiver operating characteristic curves revealed slightly superior screening capability of cumulative dose of methacholine causing a 20% decrease (PD20)‐forced expiratory volume in the first second of expiration when measured by using the APS-dosimeter method (area under the curve [AUC] 0.981 [95% confidence interval {CI}, 0.952‐1.000]) over that of cumulative dose of inhaled methacholine at the inflection point when respiratory resistance began to increase continuously (Dmin) by using the FOT (AUC 0.959 [95% CI, 0.924‐0.994]). The sensitivity and specificity were 98.9% and 98.6%, respectively, with the APS-dosimeter method, and 100% and 87.0%, respectively, with the FOT. It took an average of 9.0 minutes (range, 6.0‐11.0 minutes) when using the FOT and an average of 17.0 minutes (range, 14.0‐25.0 minutes) when using APS-dosimeter method (p < 0.01) in all the participants. The measurement time for the FOT was reduced by 47.1% than the APS-dosimeter. The incidence rate of the adverse events with the FOT was slightly higher than that with the APS-dosimeter method (p < 0.05). Both tests were well tolerated. No serious adverse event was found. Conclusion: The FOT, characterized as being simple, safe, and time saving, could be used to assess airway hyperresponsiveness in patients with asthma and worthy of clinical application.
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Fukahori, Susumu, Yasushi Obase, Chizu Fukushima, Daisuke Takao, Jun Iriki, Mutsumi Ozasa, Yoshiaki Zaizen, et al. "Determining Response to Treatment for Drug-Induced Bronchocentric Granulomatosis by the Forced Oscillation Technique." Medicina 57, no. 12 (November 30, 2021): 1315. http://dx.doi.org/10.3390/medicina57121315.
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Anti-tumor necrosis factor alpha (TNFα) therapy is widely used to treat various inflammatory conditions. Paradoxically, there are several case reports describing the development of bronchocentric granulomatosis treated with TNFα inhibitors, and it is difficult to determine the effect of treatment using conventional spirometry because the lesions are located in small airways. However, it has been reported that the forced oscillation technique (FOT) is useful in the evaluation of small airway disease in bronchial asthma or chronic obstructive pulmonary disease. We performed the FOT to determine the effect of treatment on bronchocentric granulomatosis and found it to be useful. We report the case of a 55-year-old female with ulcerative colitis who was treated with golimumab and who developed bronchocentric granulomatosis as a sarcoid-like reaction to golimumab. She was successfully treated with prednisone, and the treatment efficacy was confirmed by the FOT. The FOT may be useful in the evaluation of small airway disease in bronchocentric granulomatosis. This case may help inform clinicians of the usefulness of the FOT to assess small airway disease in various diseases.
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Ramsey, Kathryn A., Sarath C. Ranganathan, Catherine L. Gangell, Lidija Turkovic, Judy Park, Billy Skoric, Stephen M. Stick, Peter D. Sly, and Graham L. Hall. "Impact of lung disease on respiratory impedance in young children with cystic fibrosis." European Respiratory Journal 46, no. 6 (September 24, 2015): 1672–79. http://dx.doi.org/10.1183/13993003.00156-2015.
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This study aimed to evaluate the ability of the forced oscillation technique (FOT) to detect underlying lung disease in preschool children with cystic fibrosis (CF) diagnosed following newborn screening.184 children (aged 3–6 years) with CF underwent lung function testing on 422 occasions using the FOT to assess respiratory resistance and reactance at the time of their annual bronchoalveolar lavage collection and chest computed tomography scan. We examined associations between FOT outcomes and the presence and progression of respiratory inflammation, infection and structural lung disease.Children with CF who had pronounced respiratory disease, including free neutrophil elastase activity, infection with pro-inflammatory pathogens and structural lung abnormalities had similar FOT outcomes to those children without detectable lung disease. In addition, the progression of lung disease over 1 year was not associated with worsening FOT outcomes.We conclude that the forced oscillation technique is relatively insensitive to detect underlying lung disease in preschool children with CF. However, FOT may still be of value in improving our understanding of the physiological changes associated with early CF lung disease.
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Bhattarai, Prem, Stephen Myers, Collin Chia, Heinrich C. Weber, Sally Young, Andrew D. Williams, and Sukhwinder Singh Sohal. "Clinical Application of Forced Oscillation Technique (FOT) in Early Detection of Airway Changes in Smokers." Journal of Clinical Medicine 9, no. 9 (August 27, 2020): 2778. http://dx.doi.org/10.3390/jcm9092778.
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The forced oscillation technique (FOT) is a non-invasive method to assess airway function by emitting oscillatory signals into the respiratory tract during tidal ventilation. This opinion piece discusses the current use, trialled modification and future directions in utilizing FOT as a novel diagnostic tool for early detection of small airway changes in smokers. The published evidence to date has shown that FOT parameters could be a sensitive diagnostic tool to detect early respiratory changes in smokers. Multiple frequencies and the frequency dependence of resistance and reactance can provide the most valuable and early information regarding smoking induced changes in airways. Considering its non-invasiveness, lower level of discomfort to patients than spirometry, feasibility, and cost effectiveness, it could be the first-choice diagnostic technique for detection of early respiratory changes in smokers. The finding of FOT could further be supported and correlated with inflammatory markers.
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Starczewska-Dymek, L., A. Bozek, and M. Jakalski. "The Usefulness of the Forced Oscillation Technique in the Diagnosis of Bronchial Asthma in Children." Canadian Respiratory Journal 2018 (July 24, 2018): 1–7. http://dx.doi.org/10.1155/2018/7519592.
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The forced oscillation technique (FOT) requires minimal patient cooperation and is useful for children. However, comprehensive values of respiratory impedance at baseline and after the reversibility test have not been definitively confirmed. The aim of this study was to evaluate the basic parameters of FOT reactance (Xrs) and resistance (Rrs) in groups of healthy children and children with controlled and uncontrolled asthma. The second aim was the assessment of the reversibility bronchial test using the forced oscillation method in children with bronchial asthma. Materials and Methods. One hundred and six children aged from 2 to 6 years diagnosed with early-onset controlled or uncontrolled asthma and healthy controls were included in this single-center, prospective, randomized study. All asthmatic patients and healthy controls underwent basic FOT as one measurement according to the recommendation of Resmon Pro FOT. The reversibility test was then performed 15 min after the administration of 200 mcg salbutamol by MDI in all patients. Results. Basic Rrs showed significantly higher mean values in patients with uncontrolled asthma compared to patients with controlled asthma, which were in turn higher than the values for patients in the control group (11.14 ± 1.29 versus 15.71 ± 2.6 versus 9.21 ± 0.98, resp.; p<0.05). The data analysis showed similar relationships in terms of the Xrs between the studied groups (−4.76 ± 1.19 versus −7.31 ± 2.33 versus −2.11 ± 0.48, resp.; p<0.05). According to the changes in the Rrs values, 35 (66%) positive bronchial reversibility tests were obtained in 53 subjects with controlled asthma and in 39 (74%) subjects with uncontrolled asthma. Conclusions. Rrs and Xrs obtained by FOT well-discriminate patients with asthma from healthy children. A bronchial reversibility test involving the use of FOT is valuable for the diagnosis of bronchial asthma.
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Pham, Thuy T., Philip H. W. Leong, Paul D. Robinson, Thomas Gutzler, Adelle S. Jee, Gregory G. King, and Cindy Thamrin. "Automated quality control of forced oscillation measurements: respiratory artifact detection with advanced feature extraction." Journal of Applied Physiology 123, no. 4 (October 1, 2017): 781–89. http://dx.doi.org/10.1152/japplphysiol.00726.2016.
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The forced oscillation technique (FOT) can provide unique and clinically relevant lung function information with little cooperation with subjects. However, FOT has higher variability than spirometry, possibly because strategies for quality control and reducing artifacts in FOT measurements have yet to be standardized or validated. Many quality control procedures rely on either simple statistical filters or subjective evaluation by a human operator. In this study, we propose an automated artifact removal approach based on the resistance against flow profile, applied to complete breaths. We report results obtained from data recorded from children and adults, with and without asthma. Our proposed method has 76% agreement with a human operator for the adult data set and 79% for the pediatric data set. Furthermore, we assessed the variability of respiratory resistance measured by FOT using within-session variation (wCV) and between-session variation (bCV). In the asthmatic adults test data set, our method was again similar to that of the manual operator for wCV (6.5 vs. 6.9%) and significantly improved bCV (8.2 vs. 8.9%). Our combined automated breath removal approach based on advanced feature extraction offers better or equivalent quality control of FOT measurements compared with an expert operator and computationally more intensive methods in terms of accuracy and reducing intrasubject variability. NEW & NOTEWORTHY The forced oscillation technique (FOT) is gaining wider acceptance for clinical testing; however, strategies for quality control are still highly variable and require a high level of subjectivity. We propose an automated, complete breath approach for removal of respiratory artifacts from FOT measurements, using feature extraction and an interquartile range filter. Our approach offers better or equivalent performance compared with an expert operator, in terms of accuracy and reducing intrasubject variability.
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Milne, Stephen, Kanika Jetmalani, David G. Chapman, Joseph M. Duncan, Claude S. Farah, Cindy Thamrin, and Gregory G. King. "Respiratory system reactance reflects communicating lung volume in chronic obstructive pulmonary disease." Journal of Applied Physiology 126, no. 5 (May 1, 2019): 1223–31. http://dx.doi.org/10.1152/japplphysiol.00503.2018.
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Respiratory system reactance (Xrs) measured by the forced oscillation technique (FOT) is theoretically and experimentally related to lung volume. In chronic obstructive pulmonary disease (COPD), the absolute volume measured by body plethysmography includes a proportion that is inaccessible to pressure oscillations applied via the mouth, that is, a “noncommunicating” lung volume. We hypothesized that in COPD the presence of noncommunicating lung would disrupt the expected Xrs-volume relationship compared with plethysmographic functional residual capacity (FRCpleth). Instead, Xrs would relate to estimates of communicating volume, namely, expiratory reserve volume (ERV) and single-breath alveolar volume (VaSB). We examined FOT and lung function data from people with COPD ( n = 51) and from healthy volunteers ( n = 40). In healthy volunteers, we observed an expected inverse relationship between reactance at 5 Hz (X5) and FRCpleth. In contrast, there was no such relationship between X5 and FRCpleth in COPD subjects. However, there was an inverse relationship between X5 and both ERV and VaSB. Hence the theoretical Xrs-volume relationship is present in COPD but only when considering the communicating volume rather than the absolute lung volume. These findings confirm the role of reduced communicating lung volume as an important determinant of Xrs and therefore advance our understanding and interpretation of FOT measurements in COPD. NEW & NOTEWORTHY To investigate the determinants of respiratory system reactance (Xrs) measured by the forced oscillation technique (FOT) in chronic obstructive pulmonary disease (COPD), we examine the relationship between Xrs and lung volume. We show that Xrs does not relate to absolute lung volume (functional residual capacity) in COPD but instead relates only to the volume of lung in communication with the airway opening. This communicating volume may therefore be fundamental to our interpretation of FOT measurements in COPD and other pulmonary diseases.
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Alqahtani, Jaber S., Ahmad M. Al Rajeh, Abdulelah M. Aldhahir, Yousef S. Aldabayan, John R. Hurst, and Swapna Mandal. "The clinical utility of forced oscillation technique during hospitalisation in patients with exacerbation of COPD." ERJ Open Research 7, no. 4 (October 2021): 00448–2021. http://dx.doi.org/10.1183/23120541.00448-2021.
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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 out of 82) and increased to 50% (41 out of 82) in the supine position. EFL (measured by ΔXrs5Hz) and resistance at 5 Hz (Rrs5Hz) negatively correlated with forced expiratory volume in 1 s (FEV1); those with EFL had lower FEV1 (0.74±0.30 versus 0.94±0.36 L, p = 0.01) and forced vital capacity (1.7±0.55 versus 2.1±0.63 L, p = 0.009) and higher body mass index (27 (21–36) versus 23 (19–26) kg·m−2, p = 0.03) compared to those without EFL. During recovery from AECOPD, changes in EFL were 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 noninvasive, objective and effort-independent technique to measure lung function parameters during AECOPD requiring hospital admission.
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Kostorz-Nosal, Sabina, Dariusz Jastrzębski, Piotr Kubicki, Dagmara Galle, Alicja Gałeczka-Turkiewicz, Beata Toczylowska, and Dariusz Ziora. "Forced Oscillation Measurements in Patients with Idiopathic Interstitial Pneumonia Subjected to Pulmonary Rehabilitation." Journal of Clinical Medicine 11, no. 13 (June 24, 2022): 3657. http://dx.doi.org/10.3390/jcm11133657.
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(1) Background: Pulmonary rehabilitation (PR) plays a significant therapeutic role for patients with idiopathic interstitial pneumonia (IIP). The study assessed the impact of physical activity on lung function measured by forced oscillation technique (FOT). (2) Methods: The study involved 48 patients with IIP subjected to a 3-week inpatient PR. The control group included IIP patients (n = 44) on a 3-week interval without PR. All patients were assessed at baseline and after 3 weeks of PR by FOT, spirometry, plethysmography, grip strength measurement and the 6-minute walk test. (3) Results: There were no significant changes in FOT measurements in the PR group, except for reduced reactance at 11 Hz, observed in both groups (p < 0.05). Patients who completed PR significantly improved their 6-min walk distance (6MWD) and forced vital capacity (FVC). The change in 6MWD was better in patients with higher baseline reactance (p = 0.045). (4) Conclusions: Patients with IIP benefit from PR by an increased FVC and 6MWD; however, no improvement in FOT values was noticed. Slow disease progression was observed in the study and control groups, as measured by reduced reactance at 11 Hz. Patients with lower baseline reactance limitations achieve better 6MWD improvement.
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Pham, Q. T., E. Bourgkard, N. Chau, G. Willim, S. E. Megherbi, D. Teculescu, A. Bohadana, and J. P. Bertrand. "Forced oscillation technique (FOT): a new tool for epidemiology of occupational lung diseases?" European Respiratory Journal 8, no. 8 (August 1, 1995): 1307–13. http://dx.doi.org/10.1183/09031936.95.08081307.
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Farre, R., M. Rotger, and D. Navajas. "Estimation of random errors in respiratory resistance and reactance measured by the forced oscillation technique." European Respiratory Journal 10, no. 3 (March 1, 1997): 685–89. http://dx.doi.org/10.1183/09031936.97.10030685.
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The forced oscillation technique (FOT) allows the measurement of respiratory resistance (Rrs) and reactance (Xrs) and their associated coherence (gamma2). To avoid unreliable data, it is usual to reject Rrs and Xrs measurements with a gamma2 <0.95. This procedure makes it difficult to obtain acceptable data at the lowest frequencies of interest. The aim of this study was to derive expressions to compute the random error of Rrs and Xrs from gamma2 and the number (N) of data blocks involved in a FOT measurement. To this end, we developed theoretical equations for the variances and covariances of the pressure and flow auto- and cross-spectra used to compute Rrs and Xrs. Random errors of Rrs and Xrs were found to depend on the values of Rrs and Xrs, and to be proportional to ((1-gamma2)/(2 x N x gamma2))1/2. Reliable Rrs and Xrs data can be obtained in measurements with low gamma2 by enlarging the data recording (i.e. N). Therefore, the error equations derived may be useful to extend the frequency band of the forced oscillation technique to frequencies lower than usual, characterized by low coherence.
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Bizzotto, Davide, Stefano Paganini, Luca Stucchi, Matteo Palmisano Avallone, Esther Millares Ramirez, Pasquale P. Pompilio, Francesco Ferrucci, Jean-Pierre Lavoie, and Raffaele L. Dellacà. "A portable fan-based device for evaluating lung function in horses by the forced oscillation technique." Physiological Measurement 43, no. 2 (February 28, 2022): 025001. http://dx.doi.org/10.1088/1361-6579/ac522e.
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Abstract Objective. The assessment of lung mechanics in horses is nowadays based on invasive methods that may require sedation. The forced oscillation technique (FOT) allows the non-invasive assessment of respiratory mechanics during spontaneous breathing, but current devices are complex, cumbersome, expensive, and difficult to be applied in horses. Approach. We developed a portable FOT device based on a novel approach in which the pressure waveforms are generated by a servo-controlled ducted fan. This new approach allows the design of devices that are more sturdy, compact, and portable compared to already existing approaches. The prototype includes 1) a small microcontroller-based electronic board for controlling the fan and measuring flow and pressure and 2) an optimized data processing algorithm. Main results. This device provides a maximum error of 0.06 cmH2O·s/L and 0.15 cmH2O·s/L in measuring respiratory resistance and reactance during in-vitro validation. A pilot study was also performed on three healthy horses and three horses with severe equine asthma (SEA) and it demonstrated good tolerability and feasibility of the new device. Total respiratory system resistance (R rs) and reactance (X rs) significantly differed (p < 0.05) between groups. At 5 Hz, R rs was 0.66 ± 0.02 cmH2O·s/L and 0.94 ± 0.07 cmH2O·s/L in healthy and in SEA, respectively. X rs 0.38 ± 0.02 cmH2O·s/L and −0.27 ± 0.05 cmH2O·s/L. Significance. This novel approach for applying FOT allowed the development of a small, affordable, and portable device for the non-invasive evaluation of respiratory mechanics in spontaneously breathing horses, providing a useful new tool for improving veterinary respiratory medicine. Moreover, our results provide supporting evidence of the value of this novel approach for developing portable FOT devices also for applications in humans.
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Beydon, L., P. Malassine, A. M. Lorino, C. Mariette, F. Bonnet, A. Harf, and H. Lorino. "Respiratory resistance by end-inspiratory occlusion and forced oscillations in intubated patients." Journal of Applied Physiology 80, no. 4 (April 1, 1996): 1105–11. http://dx.doi.org/10.1152/jappl.1996.80.4.1105.
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Measurement of respiratory impedance by the forced oscillation technique (FOT) in intubated patients requires corrections for the flow-dependent resistance, inertance, and air compression inside the endotracheal tube (ETT). Recently, we published a method to correct respiratory impedance for the mechanical contribution of the ETT. To validate this correction, we compared the respiratory resistance obtained with this method (Rfo) to the intrinsic (Rmin) and total resistances (RT) measured by the airway-occlusion technique (OCT) in 16 intubated sedated paralyzed ventilated patients. The FOT was applied at functional residual capacity in the 4- to 32-Hz frequency range, whereas the OCT was performed at the end of a normal constant-flow inspiration. Rmin corrected with Rfo measured at 16 and 32 Hz [Rfo(16) = 1.10 x Rmin + 0.10 cmH2O.s.l-1, r = 0.96, P < 0.001; Rfo(32) = 0.93 x Rmin + 0.72 cmH2O.s.l-1, r = 0.97, P < 0.001]. RT corrected with Rfo at 4 Hz [Rfo(4) = 1.11 x RT - 1.48 cmH2O.s.l-1; = 0.92; P < 0.001]. We conclude that the FOT improved by correction for the behavior of the ETT is in good agreement with the OCT in intubated patients.
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Chinet, T., G. Pelle, I. Macquin-Mavier, H. Lorino, and A. Harf. "Comparison of the dose-response curves obtained by forced oscillation and plethysmography during carbachol inhalation." European Respiratory Journal 1, no. 7 (July 1, 1988): 600–605. http://dx.doi.org/10.1183/09031936.93.01070600.
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We compared the cumulative dose-response curves obtained during carbachol inhalation by simultaneous measurements of airway specific conductance (sGaw) and respiratory conductance, in 23 subjects with or without bronchial hyperresponsiveness. The sGaw was measured by a body plethysmograph, whilst the random noise forced oscillation technique (FOT) was used to determine respiratory conductance. The sGaw was compared to respiratory conductance extrapolated to zero frequency (Grs0). Bronchial sensitivity was assessed by the threshold dose of carbachol (TD) that induced a decrease in sGaw and Grs0 of twice the baseline coefficient of variation. Bronchial responsiveness was assessed by the slopes (S) of the individual dose-response curves. The TD and S values obtained by FOT and by plethysmography were closely correlated (p less than 0.001). The carbachol doses inducing a 50% reduction in sGaw were equivalent to those causing a 42% reduction in Grs0 (r = 0.90; p less than 0.001). During bronchial challenge testing, FOT provides comparable information in terms of bronchial sensitivity and responsiveness to that supplied by plethysmography.
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Bates, J. H., B. Daroczy, and Z. Hantos. "A comparison of interrupter and forced oscillation measurements of respiratory resistance in the dog." Journal of Applied Physiology 72, no. 1 (January 1, 1992): 46–52. http://dx.doi.org/10.1152/jappl.1992.72.1.46.
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We compared the values of resistance produced by the forced oscillation technique (FOT) and the flow interruption technique (IT) when applied to six anesthetized paralyzed tracheostomized dogs. The FOT returned values of respiratory system resistance as a function of frequency [Re(f)] between 0.25 and 20 Hz. The IT returned a single value of resistance (Rinit) calculated by dividing the immediate change in tracheal pressure occurring upon interruption by the preinterruption flow. We found Rinit to coincide closely with Re(f) in the frequency range 5–20 Hz. Rinit has previously been interpreted as the high-frequency resistance of a resistance-elastance model of the respiratory system airways and tissues. It has also been shown previously, by direct measurement of alveolar pressure in dogs, that Rinit from the lungs alone is an accurate measure of airways resistance while Rinit obtained from the total respiratory system equals airways resistance plus a modest contribution from the chest wall. Re(f) at a frequency of approximately 10 Hz thus appears to be a useful quantity to measure as an index of airways resistance in the dog.
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Watts, Joanna C., Claude S. Farah, Leigh M. Seccombe, Blake M. Handley, Robin E. Schoeffel, Amy Bertolin, Jessica Dame Carroll, Gregory G. King, and Cindy Thamrin. "Measurement duration impacts variability but not impedance measured by the forced oscillation technique in healthy, asthma and COPD subjects." ERJ Open Research 2, no. 2 (April 2016): 00094–2015. http://dx.doi.org/10.1183/23120541.00094-2015.
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The forced oscillation technique (FOT) is gaining clinical acceptance, facilitated by more commercial devices and clinical data. However, the effects of variations in testing protocols used in FOT data acquisition are unknown. We describe the effect of duration of data acquisition on FOT results in subjects with asthma, chronic obstructive pulmonary disease (COPD) and healthy controls.FOT data were acquired from 20 healthy, 22 asthmatic and 18 COPD subjects for 60 s in triplicate. The first 16, 30 and 60 s of each measurement were analysed to obtain total, inspiratory and expiratory resistance of respiratory system (Rrs) and respiratory system reactance (Xrs) at 5 and 19 Hz.With increasing duration, there was a decrease in total and expiratory Rrs for healthy controls, total and inspiratory Rrs for asthmatic subjects and magnitude of total and inspiratory Xrs for COPD subjects at 5 Hz. These decreases were small compared to the differences between clinical groups. Measuring for 16, 30 and 60 s provided ≥3 acceptable breaths in at least 90, 95 and 100% of subjects, respectively. The coefficient of variation for total Rrs and Xrs also decreased with duration. Similar results were found for Rrs and Xrs at 19 Hz.FOT results are statistically, but likely minimally, impacted by acquisition duration in healthy, asthmatic or COPD subjects.
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Ross, D. J., M. D. Goldman, R. M. Strieter, J. A. Belperio, and A. Ardehali. "Multi-frequency forced oscillation technique [FOT] for assessment of lung allograft function: a pilot study." Journal of Heart and Lung Transplantation 23, no. 2 (February 2004): S131. http://dx.doi.org/10.1016/j.healun.2003.11.264.
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Kim, Cheol Woo, Jung Sun Kim, Jung Won Park, and Chein Soo Hong. "Clinical Applications of Forced Oscillation Techniques FOT in patients with Bronchial Asthma." Korean Journal of Internal Medicine 16, no. 2 (June 30, 2001): 80–86. http://dx.doi.org/10.3904/kjim.2001.16.2.80.
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Akerman, Michael J., Venkata A. Yalamanchili, Vaidehi Kaza, Jeremy Weedon, Albert E. Heurich, and Makito Yaegashi. "The Utility of the Forced Oscillation Technique (FOT) in Assessing Bronchodilator Responsiveness in Patients with Asthma." Chest 126, no. 4 (October 2004): 796S. http://dx.doi.org/10.1378/chest.126.4_meetingabstracts.796s.
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Pradhan, Deepak, Ning Xu, Joan Reibman, Roberta M. Goldring, Yongzhao Shao, Mengling Liu, and Kenneth I. Berger. "Bronchodilator Response Predicts Longitudinal Improvement in Small Airway Function in World Trade Center Dust Exposed Community Members." International Journal of Environmental Research and Public Health 16, no. 8 (April 20, 2019): 1421. http://dx.doi.org/10.3390/ijerph16081421.
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The evolution of lung function, including assessment of small airways, was assessed in individuals enrolled in the World Trade Center Environmental Health Center (WTC-EHC). We hypothesized that a bronchodilator response at initial evaluation shown by spirometry or in small airways, as measured by forced oscillation technique (FOT), would be associated with improvement in large and small airway function over time. Standardized longitudinal assessment included pre and post bronchodilator (BD) spirometry (forced vital capacity, FVC; forced expiratory volume in 1 second, FEV1) and FOT (resistance at 5 Hz, R5; resistance at 5 minus 20 Hz, R5–20). Longitudinal changes were assessed using linear mixed-effects modelling with adjustment for potential confounders (median follow-up 2.86 years; 95% measurements within 4.9 years). Data demonstrated: (1) parallel improvement in airflow and volume measured by spirometry and small airway function (R5 and R5–20) measured by FOT; (2) the magnitude of longitudinal improvement was tightly linked to the initial BD response; and (3) longitudinal values for small airway function on FOT were similar to residual abnormality observed post BD at initial visit. These findings suggest presence of reversible and irreversible components of small airway injury that are identifiable at initial presentation. These results have implications for treatment of isolated small airway abnormalities that can be identified by non-invasive effort independent FOT particularly in symptomatic individuals with normal spirometry indices. This study underscores the need to study small airway function to understand physiologic changes over time following environmental and occupational lung injury.
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Terraneo, Silvia, Rocco Francesco Rinaldo, Giuseppe Francesco Sferrazza Papa, Fulvia Ribolla, Carlo Gulotta, Laura Maugeri, Emiliano Gatti, Stefano Centanni, and Fabiano Di Marco. "Distinct Mechanical Properties of the Respiratory System Evaluated by Forced Oscillation Technique in Acute Exacerbation of COPD and Acute Decompensated Heart Failure." Diagnostics 11, no. 3 (March 19, 2021): 554. http://dx.doi.org/10.3390/diagnostics11030554.
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Discriminating between cardiac and pulmonary dyspnea is essential for patients’ management. We investigated the feasibility and ability of forced oscillation techniques (FOT) in distinguishing between acute exacerbation of COPD (AECOPD), and acute decompensated heart failure (ADHF) in a clinical emergency setting. We enrolled 49 patients admitted to the emergency department (ED) for dyspnea and acute respiratory failure for AECOPD, or ADHF, and 11 healthy subjects. All patients were able to perform bedside FOT measurement. Patients with AECOPD showed a significantly higher inspiratory resistance at 5 Hz, Xrs5 (179% of predicted, interquartile range, IQR 94–224 vs. 100 IQR 67–149; p = 0.019), and a higher inspiratory reactance at 5 Hz (151%, IQR 74–231 vs. 57 IQR 49–99; p = 0.005) than patients with ADHF. Moreover, AECOPD showed higher heterogeneity of ventilation (respiratory system resistance difference at 5 and 19 Hz, Rrs5-19: 1.49 cmH2O/(L/s), IQR 1.03–2.16 vs. 0.44 IQR 0.22–0.76; p = 0.030), and a higher percentage of flow limited breaths compared to ADHF (10%, IQR 0–100 vs. 0 IQR 0–12; p = 0.030). FOT, which resulted in a suitable tool to be used in the ED setting, has the ability to identify distinct mechanical properties of the respiratory system in AECOPD and ADHF.
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Zimmermann, Sabine C., Jacqueline Huvanandana, Chinh D. Nguyen, Amy Bertolin, Joanna C. Watts, Alessandro Gobbi, Claude S. Farah, et al. "Day-to-day variability of forced oscillatory mechanics for early detection of acute exacerbations in COPD." European Respiratory Journal 56, no. 3 (May 19, 2020): 1901739. http://dx.doi.org/10.1183/13993003.01739-2019.
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BackgroundTelemonitoring trials for early detection of acute exacerbations of chronic obstructive pulmonary disease (AECOPD) have provided mixed results. Day-to-day variations in lung function measured by the forced oscillation technique (FOT) may yield greater insight. We evaluated the clinical utility of home telemonitoring of variability in FOT measures in terms of 1) the relationship with symptoms and quality of life (QoL); and 2) the timing of variability of FOT measures and symptom changes prior to AECOPD.MethodsDaily FOT parameters at 5 Hz (resistance (R) and reactance (X); Resmon Pro Diary, Restech Srl, Milan, Italy), daily symptoms (COPD Assessment Test (CAT)) and 4-weekly QoL data (St George's Respiratory Questionnaire (SGRQ)) were recorded over 8–9 months from chronic obstructive pulmonary disease (COPD) patients. Variability of R and X was calculated as the standard deviation (sd) over 7-day running windows and we also examined the effect of varying window size. The relationship of FOT versus CAT and SGRQ was assessed using linear mixed modelling, daily changes in FOT variability and CAT prior to AECOPD using one-way repeated measures ANOVA.ResultsFifteen participants with a mean±sd age of 69±10 years and a % predicted forced expiratory volume in 1 s (FEV1) of 39±10% had a median (interquartile range (IQR)) adherence of 95.4% (79.0–98.8%). Variability of the inspiratory component of X (indicated by the standard deviation of inspiratory reactance (SDXinsp)) related to CAT and weakly to SGRQ (fixed effect estimates 1.57, 95% CI 0.65–2.49 (p=0.001) and 4.41, 95% CI −0.06 to 8.89 (p=0.05), respectively). SDXinsp changed significantly on the same day as CAT (1 day before AECOPD, both p=0.02) and earlier when using shorter running windows (3 days before AECOPD, p=0.01; accuracy=0.72 for 5-day windows).ConclusionsSDXinsp from FOT telemonitoring reflects COPD symptoms and may be a sensitive biomarker for early detection of AECOPD.
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Frey, Urs, Bela Suki, Richard Kraemer, and Andrew C. Jackson. "Human respiratory input impedance between 32 and 800 Hz, measured by interrupter technique and forced oscillations." Journal of Applied Physiology 82, no. 3 (March 1, 1997): 1018–23. http://dx.doi.org/10.1152/jappl.1997.82.3.1018.
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Frey, Urs, Bela Suki, Richard Kraemer, and Andrew C. Jackson. Human respiratory input impedance between 32 and 800 Hz, measured by interrupter technique and forced oscillations. J. Appl. Physiol. 82(3): 1018–1023, 1997.—Respiratory input impedance (Zin) over a wide range of frequencies ( f) has been shown to be useful in determining airway resistance (Raw) and tissue resistance in dogs or airway wall properties in human adults. Zin measurements are noninvasive and, therefore, potentially useful in investigation of airway mechanics in infants. However, accurate measurements of Zin at these f values with the use of forced oscillatory techniques (FOT) in infants are difficult because of their relatively high Raw and large compliance of the face mask. If pseudorandom noise pressure oscillations generated by a loudspeaker are applied at the airway opening (FOT), the power of the resulting flow decreases inversely with f because of capacitive shunting into the volume of the gas in the speaker chamber and in the face mask. We studied whether high-frequency respiratory Zin can be measured by using rapid flow interruption [high-speed interrupter technique (HIT)], in which we expect the flow amplitude in the respiratory system to be higher than in the FOT. We compared Zin measured by HIT with Zin measured by FOT in a dried dog lung and in five healthy adult subjects. The impedance was calculated from two pressure signals measured between the mouth and the HIT valve. The impedance could be assessed from 32 to 800 Hz. Its real part at low f as well as the f and amplitude of the first and second acoustic resonance, measured by FOT and by HIT, were not significantly different. The power spectrum of oscillatory flow when the HIT was used showed amplitudes that were at least 100 times greater than those when FOT was used, increasing at f > 400 Hz. In conclusion, the HIT enables the measurement of high-frequency Zin data ranging from 32 to 800 Hz with particularly high flow amplitudes and, therefore, possibly better signal-to-noise ratio. This is particularly important in systems with high Raw, e.g., in infants, when measurements have to be performed through a face mask.
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Bellisario, Valeria, Pavilio Piccioni, Massimiliano Bugiani, Giulia Squillacioti, Stefano Levra, Carlo Gulotta, Giulio Mengozzi, Alberto Perboni, Elena Grignani, and Roberto Bono. "Tobacco Smoke Exposure, Urban and Environmental Factors as Respiratory Disease Predictors in Italian Adolescents." International Journal of Environmental Research and Public Health 16, no. 20 (October 22, 2019): 4048. http://dx.doi.org/10.3390/ijerph16204048.
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Risk monitoring in childhood is useful to estimate harmful health effects at later stages of life. Thus, here we have assessed the effects of tobacco smoke exposure and environmental pollution on the respiratory health of Italian children and adolescents using spirometry and the forced oscillation technique (FOT). For this purpose, we recruited 188 students aged 6–19 years living in Chivasso, Italy, and collected from them the following data: (1) one filled out questionnaire; (2) two respiratory measurements (i.e., spirometry and FOT); and (3) two urine tests for Cotinine (Cot) and 15-F2t-Isoprostane (15-F2t-IsoP) levels. We found a V-shape distribution for both Cotinine and 15-F2t-IsoP values, according to age groups, as well as a direct correlation (p = 0.000) between Cotinine and tobacco smoke exposure. These models demonstrate that tobacco smoke exposure, traffic, and the living environment play a fundamental role in the modulation of asthma-like symptoms (p = 0.020) and respiratory function (p = 0.007). Furthermore, the results from the 11–15-year group indicate that the growth process is a protective factor against the risk of respiratory disease later in life. Lastly, the FOT findings highlight the detrimental effects of tobacco smoke exposure and urbanization and traffic on respiratory health and asthma-like symptoms, respectively. Overall, monitoring environmental and behavioral factors in childhood can provide valuable information for preventing respiratory diseases in adulthood.
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Kelly, Vanessa J., Nathan J. Brown, Scott A. Sands, Brigitte M. Borg, Gregory G. King, and Bruce R. Thompson. "Effect of airway smooth muscle tone on airway distensibility measured by the forced oscillation technique in adults with asthma." Journal of Applied Physiology 112, no. 9 (May 1, 2012): 1494–503. http://dx.doi.org/10.1152/japplphysiol.01259.2011.
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Airway distensibility appears to be unaffected by airway smooth muscle (ASM) tone, despite the influence of ASM tone on the airway diameter-pressure relationship. This discrepancy may be because the greatest effect of ASM tone on airway diameter-pressure behavior occurs at low transpulmonary pressures, i.e., low lung volumes, which has not been investigated. Our study aimed to determine the contribution of ASM tone to airway distensibility, as assessed via the forced oscillation technique (FOT), across all lung volumes with a specific focus on low lung volumes. We also investigated the accompanying influence of ASM tone on peripheral airway closure and heterogeneity inferred from the reactance versus lung volume relationship. Respiratory system conductance and reactance were measured using FOT across the entire lung volume range in 22 asthma subjects and 19 healthy controls before and after bronchodilator. Airway distensibility (slope of conductance vs. lung volume) was calculated at residual volume (RV), functional residual capacity (FRC), and total lung capacity. At baseline, airway distensibility was significantly lower in subjects with asthma at all lung volumes. After bronchodilator, distensibility significantly increased at RV (64.8%, P < 0.001) and at FRC (61.8%, P < 0.01) in subjects with asthma but not in control subjects. The increased distensibility at RV and FRC in asthma were not associated with the accompanying changes in the reactance versus lung volume relationship. Our findings demonstrate that, at low lung volumes, ASM tone reduces airway distensibility in adults with asthma, independent of changes in airway closure and heterogeneity.
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Lebecque, P., and D. Stanescu. "Respiratory resistance by the forced oscillation technique in asthmatic children and cystic fibrosis patients." European Respiratory Journal 10, no. 4 (April 1, 1997): 891–95. http://dx.doi.org/10.1183/09031936.97.10040891.
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Measurement of the total resistance of the respiratory system (Rrs) is an attractive alternative to measurement of forced expiratory volume in one second (FEV1) in young children because it requires minimal co-operation. The purpose of this study was to assess the ability of the forced oscillation technique (FOT) to detect airway obstruction in asthmatic children and in patients with cystic fibrosis (CF). Spirometry and Rrs were recorded in 45 asthmatic children (32 males and 13 females) and in 45 patients with CF (28 males and 17 females). Rrs was measured at 10 Hz with the Siregnost FD5 (Siemens, Germany). The asthmatic children were slightly younger than the patients with CF (10+/-3 vs 14+/-7 yrs), and had milder airway obstruction (FEV1 80+/-19 vs 66+/-27% of predicted). Rrs was significantly higher in the asthmatic children (6.6+/-1.7 cmH2O x L(-1) x s) than in the patients with CF (4.8+/-1.4 cmH2O x L(-1) x s). A normal FEV1 (> or = mean -2SD) was associated with a normal Rrs (< or = mean +2SD) in 17 of the 45 asthmatic children and in 13 of the 45 CF patients. By contrast, a low FEV1 (< mean -2SD) was associated with an increased Rrs (> mean +2SD) in 21 of the 45 asthmatic children, but in only 3 of the 45 CF patients. Thus, FEV1 and Rrs yielded concordant information in asthmatic children much more often (38 out of 45) than in CF patients (16 out of 45) (p < 0.001). In CF, Rrs failed to detect even severe airways obstruction. These findings might be accounted for by the inability of Rrs to reflect peripheral obstruction. We conclude that total respiratory resistance is suitable to assess airways obstruction in asthmatic children but not in cystic fibrosis patients.
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Gray, Diane M., Dorottya Czovek, Lauren McMillan, Lidija Turkovic, Jacob A. M. Stadler, Anessa Vanker, Bence L. Radics, et al. "Intra-breath measures of respiratory mechanics in healthy African infants detect risk of respiratory illness in early life." European Respiratory Journal 53, no. 2 (January 31, 2019): 1800998. http://dx.doi.org/10.1183/13993003.00998-2018.
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Lower respiratory tract illness (LRTI) is a leading cause of mortality and morbidity in children. Sensitive and noninvasive infant lung function techniques are needed to measure risk for and impact of LRTI on lung health. The objective of this study was to investigate whether lung function derived from the intra-breath forced oscillation technique (FOT) was able to identify healthy infants at risk of LRTI in the first year of life.Lung function was measured with the novel intra-breath FOT, in 6-week-old infants in a South African birth cohort (Drakenstein Child Health Study). LRTI during the first year was confirmed by study staff. The association between baseline lung function and LRTI was assessed with logistic regression and odds ratios determined using optimal cut-off values.Of the 627 healthy infants with successful lung function testing, 161 (24%) had 238 LRTI episodes subsequently during the first year. Volume dependence of respiratory resistance (ΔR) and reactance (ΔX) was associated with LRTI. The predictive value was stronger if LRTI was recurrent (n=50 (31%): OR 2.5, ΔX), required hospitalisation (n=38 (16%): OR 5.4, ΔR) or was associated with wheeze (n=87 (37%): OR 3.9, ΔX).Intra-breath FOT can identify healthy infants at risk of developing LRTI, wheezing or severe illness in the first year of life.
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Kostorz-Nosal, Sabina, Dariusz Jastrzębski, Aleksandra Żebrowska, Agnieszka Bartoszewicz, and Dariusz Ziora. "Three Weeks of Pulmonary Rehabilitation Do Not Influence Oscillometry Parameters in Postoperative Lung Cancer Patients." Medicina 58, no. 11 (October 28, 2022): 1551. http://dx.doi.org/10.3390/medicina58111551.
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Background: Thoracic surgery is a recommended treatment option for non-small cell lung cancer patients. An important part of a patient’s therapy, which helps to prevent postoperative complications and improve quality of life, is pulmonary rehabilitation (PR). The aim of this study was to assess whether the implementation of physical activity has an influence on forced oscillation technique (FOT) values in patients after thoracic surgery due to lung cancer. Methods: In this observational study, we enrolled 54 patients after thoracic surgery due to lung cancer, 49 patients with idiopathic interstitial fibrosis (IPF), and 54 patients with chronic obstructive pulmonary disease/asthma–COPD overlap (COPD/ACO). All patients were subjected to three weeks of in-hospital PR and assessed at the baseline as well as after completing PR by FOT, spirometry, grip strength measurement, and the 6-min walk test (6MWT). Results: We observed differences between FOT values under the influence of physical activity in studied groups, mostly between patients after thoracic surgery and COPD/ACO patients; however, no significant improvement after completing PR among FOT parameters was noticed in any group of patients. Improvements in the 6MWT distance, left hand strength, and right hand strength after PR were noticed (p < 0.001, 0.002, and 0.012, respectively). Conclusions: Three weeks of pulmonary rehabilitation had no impact on FOT values in patients after thoracic surgery due to lung cancer. Instead, we observed improvements in the 6MWT distance and the strength of both hands. Similarly, no FOT changes were observed in IPF and COPD/ACO patients after completing PR.
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Downie, Sue R., Cheryl M. Salome, Sylvia Verbanck, Bruce R. Thompson, Norbert Berend, and Gregory G. King. "Effect of methacholine on peripheral lung mechanics and ventilation heterogeneity in asthma." Journal of Applied Physiology 114, no. 6 (March 15, 2013): 770–77. http://dx.doi.org/10.1152/japplphysiol.01198.2012.
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The forced oscillation technique (FOT) and multiple-breath nitrogen washout (MBNW) are noninvasive tests that are potentially sensitive to peripheral airways, with MBNW indexes being especially sensitive to heterogeneous changes in ventilation. The objective was to study methacholine-induced changes in the lung periphery of asthmatic patients and determine how changes in FOT variables of respiratory system reactance (Xrs) and resistance (Rrs) and frequency dependence of resistance (Rrs5-Rrs19) can be linked to changes in ventilation heterogeneity. The contributions of air trapping and airway closure, as extreme forms of heterogeneity, were also investigated. Xrs5, Rrs5, Rrs19, Rrs5-Rrs19, and inspiratory capacity (IC) were calculated from the FOT. Ventilation heterogeneity in acinar and conducting airways, and trapped gas (percent volume of trapped gas at functional residual capacity/vital capacity), were calculated from the MBNW. Measurements were repeated following methacholine. Methacholine-induced airway closure (percent change in forced vital capacity) and hyperinflation (change in IC) were also recorded. In 40 mild to moderate asthmatic patients, increase in Xrs5 after methacholine was predicted by increases in ventilation heterogeneity in acinar airways and forced vital capacity ( r2 = 0.37, P < 0.001), but had no correlation with ventilation heterogeneity in conducting airway increase or IC decrease. Increases in Rrs5 and Rrs5-Rrs19 after methacholine were not correlated with increases in ventilation heterogeneity, trapped gas, hyperinflation, or airway closure. Increased reactance in asthmatic patients after methacholine was indicative of heterogeneous changes in the lung periphery and airway closure. By contrast, increases in resistance and frequency dependence of resistance were not related to ventilation heterogeneity or airway closure and were more indicative of changes in central airway caliber than of heterogeneity.
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Kodaka, Norio, Toru Yamagishi, Kayo Watanabe, Kumiko Kishimoto, Chihiro Nakano, Takeshi Oshio, Kumiko Niitsuma, Nagashige Shimada, and Hiroto Matsuse. "Evaluation of Inhaled Procaterol for Potential Assist Use in Patients with Stable Chronic Obstructive Pulmonary Disease." Medical Principles and Practice 27, no. 4 (2018): 350–55. http://dx.doi.org/10.1159/000490146.
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Objectives: International guidelines recommend the use of long-acting bronchodilators for the treatment of chronic obstructive pulmonary disease (COPD), but the usefulness of short-acting bronchodilator assist use for stable COPD remains uncertain. The purpose of the present study was to objectively demonstrate the effects of assist use of procaterol, a short-acting β2-agonist, on the respiratory mechanics of stable COPD patients treated with a long-acting bronchodilator using forced oscillation technique (FOT) and conventional spirometry. We also confirmed the length of time for which procaterol assist could significantly improve the pulmonary function. Methods: We enrolled 28 outpatients with mild to severe COPD (Global Initiative for Obstructive Lung Disease stages I–III), who had used the same long-acting bronchodilator for longer than 3 months and who were in stable condition. All measures were performed using both FOT and spirometry sequentially from 15 min to 2 h after inhalation. Results: Compared to baseline, inhaled procaterol assist use modestly but significantly improved spirometric and FOT measurements within 2 h after inhalation. These significant effects continued for at least 2 h. Significant correlations were found between parameters measured by spirometry and those measured by FOT. Conclusions: Procaterol assist use modestly but significantly improved pulmonary function determined by spirometry and respiratory mechanics in patients with stable COPD treated with long-acting bronchodilators. Thus, inhaled procaterol has the potential for assist use for COPD.
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Lofgren, Jennifer L. S., Melissa R. Mazan, Edward P. Ingenito, Kara Lascola, Molly Seavey, Ashley Walsh, and Andrew M. Hoffman. "Restrained whole body plethysmography for measure of strain-specific and allergen-induced airway responsiveness in conscious mice." Journal of Applied Physiology 101, no. 5 (November 2006): 1495–505. http://dx.doi.org/10.1152/japplphysiol.00464.2006.
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The mouse is the most extensively studied animal species in respiratory research, yet the technologies available to assess airway function in conscious mice are not universally accepted. We hypothesized that whole body plethysmography employing noninvasive restraint (RWBP) could be used to quantify specific airway resistance (sRaw-RWBP) and airway responsiveness in conscious mice. Methacholine responses were compared using sRaw-RWBP vs. airway resistance by the forced oscillation technique (Raw-FOT) in groups of C57, A/J, and BALB/c mice. sRaw-RWBP was also compared with sRaw derived from double chamber plethysmography (sRaw-DCP) in BALB/c. Finally, airway responsiveness following allergen challenge in BALB/c was measured using RWBP. sRaw-RWBP in C57, A/J, and BALB/c mice was 0.51 ± 0.03, 0.68 ± 0.03, and 0.63 ± 0.05 cm/s, respectively. sRaw derived from Raw-FOT and functional residual capacity (Raw*functional residual capacity) was 0.095 cm/s, approximately one-fifth of sRaw-RWBP in C57 mice. The intra- and interanimal coefficients of variations were similar between sRaw-RWBP (6.8 and 20.1%) and Raw-FOT (3.4 and 20.1%, respectively). The order of airway responsiveness employing sRaw-RWBP was AJ > BALBc > C57 and for Raw-FOT was AJ > BALB/c = C57. There was no difference between the airway responsiveness assessed by RWBP vs. DCP; however, baseline sRaw-RWBP was significantly lower than sRaw-DCP. Allergen challenge caused a progressive decrease in the provocative concentration of methacholine that increased sRaw to 175% postsaline values based on sRaw-RWBP. In conclusion, the technique of RWBP was rapid, reproducible, and easy to perform. Airway responsiveness measured using RWBP, DCP, and FOT was equivalent. Allergen responses could be followed longitudinally, which may provide greater insight into the pathogenesis of chronic airway disease.
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Farre, R., M. Rotger, and D. Navajas. "Optimized estimation of respiratory impedance by signal averaging in the time domain." Journal of Applied Physiology 73, no. 3 (September 1, 1992): 1181–89. http://dx.doi.org/10.1152/jappl.1992.73.3.1181.
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The spontaneous breathing of a subject during measurements of respiratory impedance (Zrs) by the forced oscillation technique (FOT) induces errors that result in biased impedance estimates, especially at low frequencies. Although in standard measurements this bias may be avoided by using special impedance estimators, there are two applications of FOT for which such estimators are not useful: when a head generator is used and when measurements are made during intubation. In this paper we describe a data-processing procedure for unbiased impedance estimation for all FOT setups. The proposed estimator (Z) was devised for pseudorandom excitation and is based on time-domain signal averaging before frequency analysis. The performance of estimator Z was first analyzed by computer simulation of a head generator setup and a setup including an endotracheal tube to measure (2–32 Hz) a resistance-inertance-elastance model mimicking Zrs of a healthy subject. Second, Z was assessed during real measurements in 16 healthy subjects. The results obtained in the simulation (e.g., error in elastance was reduced from 15.6% with most conventional estimators to 3.3% with Z in simulation of head generator setup) and in the measurements in subjects (differences of less than 1.6% between Z and a reference) confirmed the theoretical lack of bias of Z and its practical suitability for the different FOT setups. In addition to its applicability in the situations in which no other unbiased estimators are available, estimator Z is also advantageous in most conventional applications of FOT, since it requires much less computing time and thus allows on-line Zrs measurements.
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Suh, Eui-Sik, Pasquale Pompilio, Swapna Mandal, Peter Hill, Georgios Kaltsakas, Patrick B. Murphy, Robert Romano, John Moxham, Raffaele Dellaca, and Nicholas Hart. "Autotitrating external positive end-expiratory airway pressure to abolish expiratory flow limitation during tidal breathing in patients with severe COPD: a physiological study." European Respiratory Journal 56, no. 3 (May 22, 2020): 1902234. http://dx.doi.org/10.1183/13993003.02234-2019.
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BackgroundThe optimal noninvasive application of external positive end-expiratory pressure (EPAP) to abolish tidal-breathing expiratory flow limitation (EFLT) and minimise intrinsic positive end-expiratory pressure (PEEPi) is challenging in COPD patients. We investigated whether auto-titrating EPAP, using the forced oscillation technique (FOT) to detect and abolish EFLT, would minimise PEEPi, work of breathing and neural respiratory drive (NRD) in patients with severe COPD.MethodsPatients with COPD with chronic respiratory failure underwent auto-titration of EPAP using a FOT-based algorithm that detected EFLT. Once optimal EPAP was identified, manual titration was performed to assess NRD (using diaphragm and parasternal intercostal muscle electromyography, EMGdi and EMGpara, respectively), transdiaphragmatic inspiratory pressure swings (ΔPdi), transdiaphragmatic pressure–time product (PTPdi) and PEEPi, between EPAP levels 2 cmH2O below to 3 cmH2O above optimal EPAP.ResultsOf 10 patients enrolled (age 65±6 years; male 60%; body mass index 27.6±7.2 kg.m−2; forced expiratory volume in 1 s 28.4±8.3% predicted), eight had EFLT, and optimal EPAP was 9 (range 4–13) cmH2O. NRD was reduced from baseline EPAP at 1 cmH2O below optimal EPAP on EMGdi and at optimal EPAP on EMGpara. In addition, at optimal EPAP, PEEPi (0.80±1.27 cmH2O versus 1.95± 1.70 cmH2O; p<0.05) was reduced compared with baseline. PTPdi (10.3±7.8 cmH2O·s−1versus 16.8±8.8 cmH2O·s−1; p<0.05) and ΔPdi (12.4±7.8 cmH2O versus 18.2±5.1 cmH2O; p<0.05) were reduced at optimal EPAP+1 cmH2O compared with baseline.ConclusionAutotitration of EPAP, using a FOT-based algorithm to abolish EFLT, minimises transdiaphragmatic pressure swings and NRD in patients with COPD and chronic respiratory failure.
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Uno, Tomoki, Tetsuya Homma, Masahiko Shigemura, Yosuke Fukuda, Tomoyuki Kimura, Chihiro Onitsuka, Tomoko Kawahara, et al. "Correlation of Arterial CO2 and Respiratory Impedance Values among Subjects with COPD." Journal of Clinical Medicine 9, no. 9 (August 31, 2020): 2819. http://dx.doi.org/10.3390/jcm9092819.
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Chronic obstructive pulmonary disease (COPD) is a respiratory illness characterized by airflow limitation and chronic respiratory symptoms with a global prevalence estimated to be more than 10% in 2010 and still on the rise. Furthermore, hypercapnic subject COPD leads to an increased risk of mortality, morbidity, and poor QoL (quality of life) than normocapnic subjects. Series of studies showed the usefulness of the forced oscillation technique (FOT) to measure small airway closure. Traditional findings suggested that hypercapnia may not be the main treating targets, but recent findings suggested that blood stream CO2 may lead to a worse outcome. This study aimed to seek the relationship between CO2 and small airway closure by using FOT. Subjects with COPD (n = 124; hypercapnia 22 and normocapnia 102) were analyzed for all pulmonary function values, FOT values, and arterial blood gas analysis. Student’s t-test, Spearman rank correlation, and multi linear regression analysis were used to analyze the data. COPD subjects with hypercapnia showed a significant increase in R5, R20, Fres, and ALX values, and a greater decrease in X5 value than normocapnic patients. Also, multiple linear regression analysis showed R5 was associated with hypercapnia. Hypercapnia may account for airway closure among subjects with COPD and this result suggests treating hypercapnia may lead to better outcomes for such a subject group.
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Berger, Kenneth I., Deepak R. Pradhan, Roberta M. Goldring, Beno W. Oppenheimer, William N. Rom, and Leopoldo N. Segal. "Distal airway dysfunction identifies pulmonary inflammation in asymptomatic smokers." ERJ Open Research 2, no. 4 (October 2016): 00066–2016. http://dx.doi.org/10.1183/23120541.00066-2016.
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Smoking induced inflammation leads to distal airway destruction. However, the relationship between distal airway dysfunction and inflammation remains unclear, particularly in smokers prior to the development of airway obstruction.Seven normal controls and 16 smokers without chronic obstructive pulmonary disease (COPD) were studied. Respiratory function was assessed using the forced oscillation technique (FOT). Abnormal FOT was defined as elevated resistance at 5 Hz (R5). Parameters reflecting distal lung function included frequency dependence of resistance (R5–20) and dynamic elastance (X5). Inflammation was quantified in concentrated bronchoalveolar lavage utilising cell count differential and cytokines expressed as concentration per mL epithelial lining fluid.All control subjects and seven smokers had normal R5. Nine smokers had elevated R5 with abnormal R5–20 and X5, indicating distal lung dysfunction. The presence of abnormal FOT was associated with two-fold higher lymphocyte and neutrophil counts (p<0.025) and with higher interleukin (IL)-8, eotaxin and fractalkine levels (p<0.01). Reactivity of R5–20 and X5 correlated with levels of IL-8, eotaxin, fractalkine, IL-12p70 and transforming growth factor-α (r>0.47, p<0.01).Distal airway dysfunction in smokers without COPD identifies the presence of distal lung inflammation that parallel reported observations in established COPD. These findings were not evident on routine pulmonary function testing and may allow the identification of smokers at risk of progression to COPD.
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Zimmermann, Sabine C., Katrina O. Tonga, and Cindy Thamrin. "Dismantling airway disease with the use of new pulmonary function indices." European Respiratory Review 28, no. 151 (March 27, 2019): 180122. http://dx.doi.org/10.1183/16000617.0122-2018.
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We are currently limited in our abilities to diagnose, monitor disease status and manage chronic airway disease like asthma and chronic obstructive pulmonary disease (COPD). Conventional lung function measures often poorly reflect patient symptoms or are insensitive to changes, particularly in the small airways where disease may originate or manifest. Novel pulmonary function tests are becoming available which help us better characterise and understand chronic airway disease, and their translation and adoption from the research arena would potentially enable individualised patient care.In this article, we aim to describe two emerging lung function tests yielding novel pulmonary function indices, the forced oscillation technique (FOT) and multiple breath nitrogen washout (MBNW). With a particular focus on asthma and COPD, this article demonstrates how chronic airway disease mechanisms have been dismantled with the use of the FOT and MBNW. We describe their ability to assess detailed pulmonary mechanics for diagnostic and management purposes including response to bronchodilation and other treatments, relationship with symptoms, evaluation of acute exacerbations and recovery, and telemonitoring. The current limitations of both tests, as well as open questions/directions for further research, are also discussed.
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Cavalcanti, Juliana V., Agnaldo J. Lopes, José M. Jansen, and Pedro L. Melo. "Alterations in Respiratory Mechanics Resulting From the Progression of Airway Obstruction in Asthmatic Subjects Analyzed by the Forced Oscillation Technique (FOT." Chest 124, no. 4 (January 2003): 137S. http://dx.doi.org/10.1378/chest.124.4_meetingabstracts.137s-a.
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Peslin, R., J. Felicio da Silva, C. Duvivier, and F. Chabot. "Respiratory mechanics studied by forced oscillations during artificial ventilation." European Respiratory Journal 6, no. 6 (June 1, 1993): 772–84. http://dx.doi.org/10.1183/09031936.93.06060772.
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Potential advantages of the forced oscillation technique over other methods for monitoring total respiratory mechanics during artificial ventilation are that it does not require patient relaxation, and that additional information may be derived from the frequency dependence of the real (Re) and imaginary (Im) parts of respiratory impedance. We wanted to assess feasibility and usefulness of the forced oscillation technique in this setting and therefore used the approach in 17 intubated patients, mechanically ventilated for acute respiratory failure. Sinusoidal pressure oscillations at 5, 10 and 20 Hz were applied at the airway opening, using a specially devised loudspeaker-type generator placed in parallel with the ventilator. Real and imaginary parts were corrected for the flow-dependent impedance of the endotracheal tube; they usually exhibited large variations during the respiratory cycle, and were computed separately for the inspiratory and expiratory phases. In many instances the real part was larger during inspiration, probably due to the larger respiratory flow, and decreased with increasing frequency. The imaginary part of respiratory impedance usually increased with increasing frequency during expiration, as expected for a predominately elastic system, but often varied little, or even decreased, with increasing frequency during inspiration. In most patients, the data were inconsistent with the usual resistance-inertance-compliance model. A much better fit was obtained with a model featuring central airways and a peripheral pathway in parallel with bronchial compliance. The results obtained with the latter model suggest that dynamic airway compression occurred during passive expiration in a number of patients. We conclude that the use of forced oscillation is relatively easy to implement during mechanical ventilation, that it allows the study of respiratory mechanics at various points in the respiratory cycle, and may help in detecting expiratory flow limitation.
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Thamrin, Cindy, Peter D. Sly, and Zoltán Hantos. "Broadband frequency dependence of respiratory impedance in rats." Journal of Applied Physiology 99, no. 4 (October 2005): 1364–71. http://dx.doi.org/10.1152/japplphysiol.00383.2005.
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Past studies in humans and other species have revealed the presence of resonances and antiresonances, i.e., minima and maxima in respiratory system impedance (Zrs), at frequencies much higher than those commonly employed in clinical applications of the forced oscillation technique (FOT). To help understand the mechanisms behind the first occurrence of antiresonance in the Zrs spectrum, the frequency response of the rat was studied by using FOT at both low and high frequencies. We measured Zrs in both Wistar and PVG/c rats using the wave tube technique, with a FOT signal ranging from 2 to 900 Hz. We then compared the high-frequency parameters, i.e., the first antiresonant frequency (far,1) and the resistive part of Zrs at that frequency [Rrs(far,1)], with parameters obtained by fitting a modified constant-phase model to low-frequency Zrs spectra. The far,1 was 570 ± 43 (SD) Hz and 456 ± 16 Hz in Wistar and PVG/c rats, respectively, and it did not shift with respiratory gases of different densities (air, heliox, and a mixture of SF6). The far,1 and Rrs(far,1) were relatively independent of methacholine-induced bronchoconstriction but changed significantly with increasing transrespiratory pressures up to 20 cmH2O, in the same way as airway resistance but independently of changes to tissue parameters. These results suggest that, unlike the human situation, the first antiresonance in the rat is not primarily dependent on the acoustic dimensions of the respiratory system and can be explained by interactions between compliances and inertances localized to the airways, but this most likely does not include airway wall compliance.
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Milne, Stephen, Jacqueline Huvanandana, Chinh Nguyen, Joseph M. Duncan, David G. Chapman, Katrina O. Tonga, Sabine C. Zimmermann, Alexander Slattery, Gregory G. King, and Cindy Thamrin. "Time-based pulmonary features from electrical impedance tomography demonstrate ventilation heterogeneity in chronic obstructive pulmonary disease." Journal of Applied Physiology 127, no. 5 (November 1, 2019): 1441–52. http://dx.doi.org/10.1152/japplphysiol.00304.2019.
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Pulmonary electrical impedance tomography (EIT) is a functional imaging technique that allows real-time monitoring of ventilation distribution. Ventilation heterogeneity (VH) is a characteristic feature of chronic obstructive pulmonary disease (COPD) and has previously been quantified using features derived from tidal variations in the amplitude of the EIT signal. However, VH may be better described by time-based metrics, the measurement of which is made possible by the high temporal resolution of EIT. We aimed 1) to quantify VH using novel time-based EIT metrics and 2) to determine the physiological relevance of these metrics by exploring their relationships with complex lung mechanics measured by the forced oscillation technique (FOT). We performed FOT, spirometry, and tidal-breathing EIT measurements in 11 healthy controls and 9 volunteers with COPD. Through offline signal processing, we derived 3 features from the impedance-time ( Z- t) curve for each image pixel: 1) tE, mean expiratory time; 2) PHASE, mean time difference between pixel and global Z- t curves; and 3) AMP, mean amplitude of Z- t curve tidal variation. Distribution was quantified by the coefficient of variation (CV) and the heterogeneity index (HI). Both CV and HI of the tE and PHASE features were significantly increased in COPD compared with controls, and both related to spirometry and FOT resistance and reactance measurements. In contrast, distribution of the AMP feature showed no relationships with lung mechanics. These novel time-based EIT metrics of VH reflect complex lung mechanics in COPD and have the potential to allow real-time visualization of pulmonary physiology in spontaneously breathing subjects. NEW & NOTEWORTHY Pulmonary electrical impedance tomography (EIT) is a real-time imaging technique capable of monitoring ventilation with exquisite temporal resolution. We report novel, time-based EIT measurements that not only demonstrate ventilation heterogeneity in chronic obstructive pulmonary disease (COPD), but also reflect oscillatory lung mechanics. These EIT measurements are noninvasive, radiation-free, easy to obtain, and provide real-time visualization of the complex pathophysiology of COPD.
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Kobori, Taiga, Mizuho Nagao, and Takao Fujisawa. "Changes in forced oscillation technique (FOT) parameters during 4-year-follow-up in children and adolescents with asthma: possible indices for lung function decline." Journal of Allergy and Clinical Immunology 143, no. 2 (February 2019): AB9. http://dx.doi.org/10.1016/j.jaci.2018.12.029.
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Peslin, R., Y. Ying, C. Gallina, and C. Duvivier. "Within-breath variations of forced oscillation resistance in healthy subjects." European Respiratory Journal 5, no. 1 (January 1, 1992): 86–92. http://dx.doi.org/10.1183/09031936.93.05010086.
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Respiratory resistance (Rrs) was measured by the forced oscillation technique at 10, 20 and 30 Hz in 54 healthy subjects. The sinusoidal pressure oscillations were applied around the head, rather than at the mouth, so as to minimize transmural pressure across extrathoracic airway walls and the corresponding artefact (Peslin et al., J Appl Physiol, 1985, 59, 1790-1795). The flow (V') and volume (V) dependences of Rrs during the respiratory cycle were analysed by least square regression according to: Rrs = K1 + 2.K2.[V']#- K3.V, where K1 and K2 are Rohrer's constants, and where K3 expresses the (negative) volume dependence of Rrs. The analysis was made separately on the inspiratory and expiratory phases. A good fit was usually found between the data and the model, with a root-mean-square error averaging 15% of the mean Rrs at 10 Hz. At all frequencies K2 and K3 were substantially and significantly larger, and K1 slightly lower during expiration than during inspiration. Rrs, K1 and K3 were minimum at 20 Hz, while K2 exhibited a strong positive frequency dependence. The decrease of Rrs from 10 to 20 Hz was entirely explained by the variations of its linear component, and its increase from 20 to 30 Hz was largely due to its flow dependent component. Both the phasic variations and the frequency dependence of the coefficients suggest that the model is purely descriptive and that coefficients K2 and K3 reflect a number of phenomena, including the variations in glottic aperture during the respiratory cycle.
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Young, Heather M., Fumin Guo, Rachel L. Eddy, Geoffrey Maksym, and Grace Parraga. "Oscillometry and pulmonary MRI measurements of ventilation heterogeneity in obstructive lung disease: relationship to quality of life and disease control." Journal of Applied Physiology 125, no. 1 (July 1, 2018): 73–85. http://dx.doi.org/10.1152/japplphysiol.01031.2017.
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Ventilation heterogeneity is a hallmark finding in obstructive lung disease and may be evaluated using a variety of methods, including multiple-breath gas washout and pulmonary imaging. Such methods provide an opportunity to better understand the relationships between structural and functional abnormalities in the lungs, and their relationships with important clinical outcomes. We measured ventilation heterogeneity and respiratory impedance in 100 subjects [50 patients with asthma, 22 ex-smokers, and 28 patients with chronic obstructive pulmonary disease (COPD)] using oscillometry and hyperpolarized 3He magnetic resonance imaging (MRI) and determined their relationships with quality of life scores and disease control/exacerbations. We also coregistered MRI ventilation maps to a computational airway tree model to generate patient-specific respiratory impedance predictions for comparison with experimental measurements. In COPD and asthma patients, respectively, forced oscillation technique (FOT)-derived peripheral resistance (5–19 Hz) and MRI ventilation defect percentage (VDP) were significantly related to quality of life (FOT: COPD ρ = 0.4, P = 0.004; asthma ρ = −0.3, P = 0.04; VDP: COPD ρ = 0.6, P = 0.003; asthma ρ = −0.3, P = 0.04). Patients with poorly controlled asthma (Asthmatic Control Questionnaire >2) had significantly increased resistance (5 Hz: P = 0.01; 5–19 Hz: P = 0.006) and reactance (5 Hz: P = 0.03). FOT-derived peripheral resistance (5–19 Hz) was significantly related to VDP in patients with asthma and COPD patients (asthma: ρ = 0.5, P < 0.001; COPD: ρ = 0.5, P = 0.01), whereas total respiratory impedance was related to VDP only in patients with asthma (resistance 5 Hz: ρ = 0.3, P = 0.02; reactance 5 Hz: ρ = −0.5, P < 0.001). Model-predicted and FOT-measured reactance (5 Hz) were correlated in patients with asthma (ρ = 0.5, P = 0.001), whereas in COPD patients, model-predicted and FOT-measured resistance (5–19 Hz) were correlated (ρ = 0.5, P = 0.004). In summary, in patients with asthma and COPD patients, we observed significant, independent relationships for FOT-measured impedance and MRI ventilation heterogeneity measurements with one another and with quality of life scores. NEW & NOTEWORTHY In 100 patients, including patients with asthma and ex-smokers, 3He MRI ventilation heterogeneity and respiratory system impedance were correlated and both were independently related to quality of life scores and asthma control. These findings demonstrated the critical relationships between respiratory system impedance and ventilation heterogeneity and their role in determining quality of life and disease control. These observations underscore the dominant role that abnormalities in the lung periphery play in ventilation heterogeneity that results in patients’ symptoms.
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van Hengstum, M., J. Festen, C. Beurskens, M. Hankel, W. van den Broek, and F. Corstens. "No effect of oral high frequency oscillation combined with forced expiration manoeuvres on tracheobronchial clearance in chronic bronchitis." European Respiratory Journal 3, no. 1 (January 1, 1990): 14–18. http://dx.doi.org/10.1183/09031936.93.03010014.
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This study compared the effect of oral high frequency oscillation (OHFO) with the effect of the forced expiration technique (FET) on tracheobronchial clearance. Eight patients with chronic bronchitis were investigated (mean age 60 +/- 10 yrs, mean forced expiratory volume in one second (FEV1) 68 +/- 27% predicted, mean sputum production 33 +/- 9 g.day-1). OHFO was applied at the respiratory system resonant frequency of each patient (range 9.2-25 Hz) and combined with huffing. FET included breathing exercises, huffing and postural drainage. Duration of both OHFO and FET was 30 minutes. Tracheobronchial clearance was measured by means of a radio-aerosol technique. At 60 mins after start of the treatment mean tracheobronchial retention was 70 +/- 26% after OHFO, 54 +/- 26% after FET and 76 +/- 18% in the control run, which included huffing only. OHFO was not significantly different from control. FET was significantly different (p less than 0.02) from both OHFO and control. It is concluded that OHFO has no effect on tracheobronchial clearance in chronic bronchitis.
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Vij, Neeraj. "Prognosis-Based Early Intervention Strategies to Resolve Exacerbation and Progressive Lung Function Decline in Cystic Fibrosis." Journal of Personalized Medicine 11, no. 2 (February 3, 2021): 96. http://dx.doi.org/10.3390/jpm11020096.
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Cystic fibrosis (CF) is a genetic disease caused by a mutation(s) in the CF transmembrane regulator (CFTR), where progressive decline in lung function due to recurring exacerbations is a major cause of mortality. The initiation of chronic obstructive lung disease in CF involves inflammation and exacerbations, leading to mucus obstruction and lung function decline. Even though clinical management of CF lung disease has prolonged survival, exacerbation and age-related lung function decline remain a challenge for controlling the progressive lung disease. The key to the resolution of progressive lung disease is prognosis-based early therapeutic intervention; thus, the development of novel diagnostics and prognostic biomarkers for predicting exacerbation and lung function decline will allow optimal management of the lung disease. Hence, the development of real-time lung function diagnostics such as forced oscillation technique (FOT), impulse oscillometry system (IOS), and electrical impedance tomography (EIT), and novel prognosis-based intervention strategies for controlling the progression of chronic obstructive lung disease will fulfill a significant unmet need for CF patients. Early detection of CF lung inflammation and exacerbations with the timely resolution will not only prolong survival and reduce mortality but also improve quality of life while reducing significant health care costs due to recurring hospitalizations.
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Ferrante, Giuliana, Rossana Rossi, Giovanna Cilluffo, Dario Di Silvestre, Andrea Brambilla, Antonella De Palma, Chiara Villa, et al. "Shotgun Proteomics of Isolated Urinary Extracellular Vesicles for Investigating Respiratory Impedance in Healthy Preschoolers." Molecules 26, no. 5 (February 26, 2021): 1258. http://dx.doi.org/10.3390/molecules26051258.
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Urine proteomic applications in children suggested their potential in discriminating between healthy subjects from those with respiratory diseases. The aim of the current study was to combine protein fractionation, by urinary extracellular vesicle isolation, and proteomics analysis in order to establish whether different patterns of respiratory impedance in healthy preschoolers can be characterized from a protein fingerprint. Twenty-one 3–5-yr-old healthy children, representative of 66 recruited subjects, were selected: 12 late preterm (LP) and 9 full-term (T) born. Children underwent measurement of respiratory impedance through Forced Oscillation Technique (FOT) and no significant differences between LP and T were found. Unbiased clustering, based on proteomic signatures, stratified three groups of children (A, B, C) with significantly different patterns of respiratory impedance, which was slightly worse in group A than in groups B and C. Six proteins (Tripeptidyl peptidase I (TPP1), Cubilin (CUBN), SerpinA4, SerpinF1, Thy-1 membrane glycoprotein (THY1) and Angiopoietin-related protein 2 (ANGPTL2)) were identified in order to type the membership of subjects to the three groups. The differential levels of the six proteins in groups A, B and C suggest that proteomic-based profiles of urinary fractionated exosomes could represent a link between respiratory impedance and underlying biological profiles in healthy preschool children.
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van Noord, JA, M. Cauberghs, KP Van de Woestijne, and M. Demedts. "Total respiratory resistance and reactance in ankylosing spondylitis and kyphoscoliosis." European Respiratory Journal 4, no. 8 (September 1, 1991): 945–51. http://dx.doi.org/10.1183/09031936.93.04080945.
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Ankylosing spondylitis and kyphoscoliosis both alter the function of the lung by modifying the mechanical properties of the thoracic cage. The purpose of the present study was to assess the changes in total respiratory resistance (Rrs) and reactance (Xrs) in these patients and to compare these data with conventional pulmonary function tests. In 16 patients with ankylosing spondylitis and seven with kyphoscoliosis we measured lung volumes, maximal flows, diffusing capacity, airway resistance, lung compliance and Rrs and Xrs between 2-26 Hz by means of the forced oscillation technique (FOT). In the patients with ankylosing spondylitis mean total lung capacity was 83% predicted (range 60-105%). Mean values of Rrs were normal; there was a small decrease in Xrs at the lowest frequency. In the patients with kyphoscoliosis mean total lung capacity (TLC) was 41% predicted for arm span (range 26-75%). Mean Rrs was elevated with a negative frequency dependence, and mean Xrs was decreased. The observed differences in Rrs and Xrs between the two groups of patients are related to differences in severity of the restriction. There is evidence that the changes in Rrs and Xrs in both groups are mainly attributable to an increase in chest wall resistance and a decrease in chest wall compliance, while in the patients with kyphoscoliosis an increase in airway resistance and a decrease in lung compliance also intervenes.