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Raffaele Dellaca - One of the best experts on this subject based on the ideXlab platform.
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Forced Oscillation Technique and small airway involvement in chronic hypersensitivity pneumonitis
Archivos De Bronconeumologia, 2019Co-Authors: Olivia Meira Dias, Raffaele Dellaca, Bruno Guedes Baldi, Rodrigo Caruso Chate, Carlos Roberto Ribeiro De Carvalho, Ilaria Milesi, Andrec Luis Pereira De AlbuquerqueAbstract:Abstract Objective Hypersensitivity pneumonitis (HP) is an interstitial lung disease caused by the inhalation of specific organic antigens or low-molecular weight substances in genetically susceptible individuals. Although small airway involvement is prominent in patients with chronic HP, conventional pulmonary function tests (PFTs) are relatively insensitive to identify it. Thus, the authors aimed to evaluate resistance (R5) and reactance (X5) values at 5 Hz on inspiration, expiration, and whole breath, as well as small airway resistance (R5–19) values using a Forced Oscillation Technique (FOT) in patients with chronic HP, and their responses after bronchodilator. In addition, R5 and X5 values according to the presence or absence of mosaic attenuation on computed tomography (CT) were compared. Methods PFTs with plethysmography, diffusing capacity of the lungs for carbon monoxide (DLCO) and FOT measurements were performed pre-bronchodilator and post-bronchodilator. High-resolution CT was performed at the same visit, and classified according to the presence or absence of mosaic attenuation. R5 and X5 values were then compared according to the presence or absence of mosaic attenuation on CT. Results Twenty-eight patients with chronic HP (57.1% female; mean age, 56 ± 11.5 years; mean Forced vital capacity 57 ± 17% predicted) were evaluated. All patients had low X5 values, reflecting lower lung compliance, and only three (8%) demonstrated elevated R5 (whole-breath) values. No patients exhibited bronchodilator response in R5, X5 and R5–19 values. In patients who exhibited greater extension of mosaic attenuation (n = 11), R5 and X5 values could not discriminate those with a greater presence of these areas on CT. Conclusions The results suggest that FOT does not help to additionally characterise concomitant small airway involvement in patients with chronic fibrotic HP who demonstrate restrictive ventilatory pattern in conventional PFTs. Nevertheless, FOT appeared to better characterise decreased lung compliance due to fibrosis through X5. Bronchodilator therapy did not appear to induce an acute response in chronic HP patients with restrictive disease. The precise role of FOT in subacute HP and obstructive chronic HP, therefore, must be evaluated.
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closing volume detection by single breath gas nitrogen washout and Forced Oscillation Technique
European Respiratory Journal, 2013Co-Authors: Chiara Veneroni, Raffaele Dellaca, Andrei Malinovschi, Alain Van Muylem, Alain MichilsAbstract:BACKGROUND: Single breath nitrogen washout (SBW) is considered as the Gold Standard in detecting closing volume (CV), which allows an early detection of small airways diseases. Recent studies have shown that respiratory input reactance at 5Hz (X 5 ) measured by Forced Oscillation Technique (FOT) may also detect peripheral airways collapse (Dellaca et al.,2011). AIM: to evaluate whether FOT allows CV estimation and to validate it against SBW. METHODS: SBW and FOT at 5, 11 and 19Hz during a slow vital capacity were performed in 8 healthy subjects and 11 asthmatics. CV N2 from SBW was identified by a blinded expert. A sigmoidal function was used to fit the volume vs X 5 curves and CV FOT was defined as the point of maximal downward curvature. CV was expressed as percentage of vital capacity. In healthy subjects, measurements were performed in triplicate to assess repeatability. Asthmatics were studied pre and post methacholine challenge (Mch) at 20% fall in FEV1. RESULTS: In healthy subjects, CV N2 and CV FOT coefficients of variation were 21% and 27% (p=0.8,Wilcoxon Signed Rank).CV FOT correlated with CV N2 as a whole (ρ=0.6, p FOT but not CV N2 was different between healthy and asthmatics pre-Mch (7.6% vs. 11.2%, p=0.03; 15.7% vs 14.0%, p=0.65; Mann-Whitney Rank Sum). Both FOT and SBW identify a difference between the CV pre and post Mch (CV FOT 11.2% vs 30.8%, p=0.001; CV N2 14.0% vs 31.6%, p=0.002; Wilcoxon Signed Rank). CONCLUSIONS: FOT allowed the identification of a reproducible CV FOT which correlated with CV N2 . Differences in FOT-assessed CV between healthy and asthmatics might suggest that CV FOT is a more sensitive marker of small airways involvement than CV N2 .
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the use of Forced Oscillation Technique fot to assess small airways dysfunction
European Respiratory Journal, 2013Co-Authors: Andrei Malinovschi, Chiara Veneroni, Alain Michils, Alain Van Muylem, Raffaele DellacaAbstract:BACKGROUND: The slope of third phase (SIII) of single breath nitrogen washout (SBN2) assesses ventilation heterogeneity and indirectly small airway involvement. By performing the SBW maneuver at operating volumes, SIII closer relates to small airways dysfunction (Van Muylem et al. 1992). Recent studies suggest that lung impedance (Zrs) measured by FOT is sensitive to small airways obstruction. AIM: to study the relationship between SIII and Zrs parameters obtained during spontaneous breathing. METHODS: Assessment of SIII for SBN2 measurements, both at VC (SIIIN2(VC)) and at operating volume, FRC to FRC+1L (SIIIN2(FRC+1L)), was done in 4 healthy adults and 10 asthmatics. Inspiratory within-breath Zrs at 5, 11 and 19 Hz was measured by FOT and expressed as resistance (R) and reactance (X). All measurements were repeated in asthmatics after methacholine challenge (Mch) at 20% fall in FEV1. RESULTS: Log-transformed SIIIN2(VC) correlated significantly to X5, X11, X19, R5, and R5-R19 (p<0.05). The correlations between above named FOT parameters and log-transformed SIIIN2(FRC+1L) were slightly stronger: X5 (R2=0.43 vs 0.40 for SIIIN2(VC)), X11(R2=0.43 vs 0.38), X19 (R2=0.55 vs 0.37) and R5-R19 (R2=0.39 vs 0.37). Significant changes of SIIIN2(VC), SIIIN2(FRC+1L) and all studied FOT parameters were found after Mch (p<0.01). The FOT parameters with largest relative changes (at least 100%) after Mch were: X5, X11, X19 and R5-R19. CONCLUSIONS: FOT appears to be useful to detect small airways obstruction both at baseline conditions and after bronchial challenge. Reactance at all investigated frequencies and the frequency dependence of resistance might be promising FOT-markers of small airways dysfunction.
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optimizing positive end expiratory pressure by oscillatory mechanics minimizes tidal recruitment and distension an experimental study in a lavage model of lung injury
Critical Care, 2012Co-Authors: Emanuela Zannin, Peter Kostic, Pasquale Pompilio, Antonio Pedotti, Raffaele Dellaca, Goran Hedenstierna, Anders Larsson, Peter FrykholmAbstract:Introduction It is well established that during mechanical ventilation of patients with acute respiratory distress syndrome cyclic recruitment/derecruitment and overdistension are potentially injurious for lung tissues. We evaluated whether the Forced Oscillation Technique (FOT) could be used to guide the ventilator settings in order to minimize cyclic lung recruitment/derecruitment and cyclic mechanical stress in an experimental model of acute lung injury.
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positive end expiratory pressure optimization with Forced Oscillation Technique reduces ventilator induced lung injury a controlled experimental study in pigs with saline lavage lung injury
Critical Care, 2011Co-Authors: Peter Kostic, Marie Andersson Olerud, Peter Frykholm, Pasquale Pompilio, Antonio Pedotti, Emanuela Zannin, Goran Hedenstierna, Anders Larsson, Raffaele DellacaAbstract:Introduction Protocols using high levels of positive end-expiratory pressure (PEEP) in combination with low tidal volumes have been shown to reduce mortality in patients with severe acute respiratory distress syndrome (ARDS). However, the optimal method for setting PEEP is yet to be defined. It has been shown that respiratory system reactance (Xrs), measured by the Forced Oscillation Technique (FOT) at 5 Hz, may be used to identify the minimal PEEP level required to maintain lung recruitment. The aim of the present study was to evaluate if using Xrs for setting PEEP would improve lung mechanics and reduce lung injury compared to an oxygenation-based approach.
Gregory G King - One of the best experts on this subject based on the ideXlab platform.
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bronchodilator response assessed by the Forced Oscillation Technique identifies poor asthma control with greater sensitivity than spirometry
Chest, 2020Co-Authors: Alice M Cottee, Leigh M Seccombe, Gregory G King, Cindy Thamrin, Matthew J PetersAbstract:Background Persistent bronchodilator response (BDR) following diagnosis of asthma is an underrecognized treatable trait, associated with worse lung function and asthma control. The Forced Oscillation Technique (FOT) measures respiratory system impedance, and BDR cutoffs have been proposed for healthy adults; however, the relevance in asthma is unknown. We compared BDR cutoffs, using FOT and spirometry, in asthma and the relationship with asthma control. Methods Data from patients with asthma who withheld bronchodilator medication for at least 8 h before a tertiary airway clinic visit were reviewed. All subjects performed FOT and spirometry before and after salbutamol administration, and completed the Asthma Control Test. FOT parameters examined included respiratory system resistance (R5) and reactance (X5) at 5 Hz, and area under the reactance curve (AX). BDR was defined by standard recommendations for spirometry and based on the 95th percentile of BDR in healthy adults for FOT. Results Fifty-two subjects (18 men; mean age, 53 ± 18 years) were included. BDR was identified more frequently by FOT than spirometry (54% vs 27% of subjects). BDR assessed by X5 and AX, but not R5, was associated with spirometric BDR (χ2, P Conclusions BDR assessed by FOT can identify poor asthma control. Reactance parameters were more sensitive in identifying poor asthma control than spirometry, supporting the use of FOT to complement spirometry in the clinical management of asthma.
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early onset of airway derecruitment assessed using the Forced Oscillation Technique in subjects with asthma
Journal of Applied Physiology, 2019Co-Authors: Kris Nilsen, Matt J Ellis, Francis Thien, Gregory G King, Cindy Thamrin, Kim G PriskAbstract:This study demonstrates that the Forced Oscillation Technique can be used to identify two lung volume points where lung derecruitment occurs: 1) where derecruitment is initiated and 2) where onset ...
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automated quality control of Forced Oscillation measurements respiratory artifact detection with advanced feature extraction
Journal of Applied Physiology, 2017Co-Authors: Thuy T Pham, Paul Robinson, Thomas Gutzler, Gregory G King, Philip H W Leong, Cindy ThamrinAbstract: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. ...
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measurement duration impacts variability but not impedance measured by the Forced Oscillation Technique in healthy asthma and copd subjects
ERJ Open Research, 2016Co-Authors: Joanna Watts, Leigh M Seccombe, C S Farah, Blake M Handley, Robin E Schoeffel, Amy Bertolin, Jessica Dame Carroll, Gregory G KingAbstract: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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effect of airway smooth muscle tone on airway distensibility measured by the Forced Oscillation Technique in adults with asthma
Journal of Applied Physiology, 2012Co-Authors: Vanessa J Kelly, Nathan J Brown, Gregory G King, Scott A Sands, Brigitte M Borg, Bruce ThompsonAbstract: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.
Antonio Pedotti - One of the best experts on this subject based on the ideXlab platform.
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optimizing positive end expiratory pressure by oscillatory mechanics minimizes tidal recruitment and distension an experimental study in a lavage model of lung injury
Critical Care, 2012Co-Authors: Emanuela Zannin, Peter Kostic, Pasquale Pompilio, Antonio Pedotti, Raffaele Dellaca, Goran Hedenstierna, Anders Larsson, Peter FrykholmAbstract:Introduction It is well established that during mechanical ventilation of patients with acute respiratory distress syndrome cyclic recruitment/derecruitment and overdistension are potentially injurious for lung tissues. We evaluated whether the Forced Oscillation Technique (FOT) could be used to guide the ventilator settings in order to minimize cyclic lung recruitment/derecruitment and cyclic mechanical stress in an experimental model of acute lung injury.
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positive end expiratory pressure optimization with Forced Oscillation Technique reduces ventilator induced lung injury a controlled experimental study in pigs with saline lavage lung injury
Critical Care, 2011Co-Authors: Peter Kostic, Marie Andersson Olerud, Peter Frykholm, Pasquale Pompilio, Antonio Pedotti, Emanuela Zannin, Goran Hedenstierna, Anders Larsson, Raffaele DellacaAbstract:Introduction Protocols using high levels of positive end-expiratory pressure (PEEP) in combination with low tidal volumes have been shown to reduce mortality in patients with severe acute respiratory distress syndrome (ARDS). However, the optimal method for setting PEEP is yet to be defined. It has been shown that respiratory system reactance (Xrs), measured by the Forced Oscillation Technique (FOT) at 5 Hz, may be used to identify the minimal PEEP level required to maintain lung recruitment. The aim of the present study was to evaluate if using Xrs for setting PEEP would improve lung mechanics and reduce lung injury compared to an oxygenation-based approach.
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optimisation of positive end expiratory pressure by Forced Oscillation Technique in a lavage model of acute lung injury
Intensive Care Medicine, 2011Co-Authors: Raffaele Dellaca, Peter Kostic, Marie Andersson Olerud, Pasquale Pompilio, Antonio Pedotti, Emanuela Zannin, Goran Hedenstierna, Peter FrykholmAbstract:Purpose We evaluated whether oscillatory compliance (CX5) measured by Forced Oscillation Technique (FOT) at 5 Hz may be useful for positive end-expiratory pressure (PEEP) optimisation.
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home monitoring of within breath respiratory mechanics by a simple and automatic Forced Oscillation Technique device
Physiological Measurement, 2010Co-Authors: Raffaele Dellaca, Miriam Pastena, Alessandro Gobbi, Antonio Pedotti, Bartolome CelliAbstract:Spirometry is the gold standard to determine the presence of airflow obstruction, but it requires volitional participation and needs qualified supervision. The Forced Oscillation Technique (FOT) measures respiratory input impedance (Zrs) during spontaneous breathing and it could be useful for unsupervised monitoring of airway obstruction. We developed a FOT device for home monitoring of Zrs which transmits the data through the Internet. Its accuracy, stability and reliability were evaluated in a pilot study measuring the Zrs in the unsupervised self-measurements of five healthy subjects. Finally, to explore the applicability of the concept, 36 consecutive daily home measurements were recorded from one healthy subject and one chronic obstructive pulmonary disease (COPD) patient. The accuracy of the device fulfilled FOT guidelines, and the reliability test showed a mean discrepancy of resistance of 0.10 ± 0.01 cmH2O s L−1. The data from the healthy subjects demonstrated high repeatability in assessing Zrs. The measurements on the healthy subjects and the patient with COPD suggest the feasibility of unsupervised FOT measurements. The healthy subjects showed minimal daily variations in Zrs, whereas the patient with COPD had large differences in mean values and important fluctuations over day-to-day measurements. The results of the pilot study demonstrate that unsupervised home monitoring of Zrs using the FOT yields accurate and reproducible data. It could provide new insights into the dynamics of airway obstruction and improve the understanding and management of obstructive diseases.
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expiratory flow limitation detected by Forced Oscillation and negative expiratory pressure
European Respiratory Journal, 2006Co-Authors: Raffaele Dellaca, Nick Duffy, Pasquale Pompilio, Antonio Pedotti, Nikolaos Koulouris, Andrea Aliverti, Peter M A CalverleyAbstract:The within-breath change in reactance (Δ X rs ) measured by Forced Oscillation Technique (FOT) at 5 Hz reliably detects expiratory flow limitation in chronic obstructive pulmonary disease (COPD). The present study compared this approach to the standard negative expiratory pressure (NEP) method. In total, 21 COPD patients were studied by applying both Techniques to the same breath and in 15 patients the measurements were repeated after bronchodilator. For each patient and condition five NEP tests were performed and independently scored by three operators unaware of the FOT results. In 180 tests, FOT classified 53.3% as flow limited. On average, the operators scored 27.6% of tests flow limited and 47.6% non-flow limited, but could not score 24.8%. The methods disagreed in 7.9% of cases; in 78% of these the NEP scores differed between operators. Bronchodilation reduced NEP and Δ X rs scores, with only the latter achieving significance. Averaging the operators′ NEP scores, a threshold between 24.6–30.8% of tidal volume being flow limited by NEP produced 94% agreement between methods. In conclusion, when negative expiratory pressure and Forced Oscillation Technique were both available they showed good agreement. As Forced Oscillation Technique is automatic and can measure multiple breaths over long periods, it is suitable for monitoring expiratory flow limitation continuously and identifying patients′ breathing close to the onset of expiratory flow limitation, where intermittent sampling may be unrepresentative.
Peter M A Calverley - One of the best experts on this subject based on the ideXlab platform.
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expiratory flow limitation detected by Forced Oscillation and negative expiratory pressure
European Respiratory Journal, 2006Co-Authors: Raffaele Dellaca, Nick Duffy, Pasquale Pompilio, Antonio Pedotti, Nikolaos Koulouris, Andrea Aliverti, Peter M A CalverleyAbstract:The within-breath change in reactance (Δ X rs ) measured by Forced Oscillation Technique (FOT) at 5 Hz reliably detects expiratory flow limitation in chronic obstructive pulmonary disease (COPD). The present study compared this approach to the standard negative expiratory pressure (NEP) method. In total, 21 COPD patients were studied by applying both Techniques to the same breath and in 15 patients the measurements were repeated after bronchodilator. For each patient and condition five NEP tests were performed and independently scored by three operators unaware of the FOT results. In 180 tests, FOT classified 53.3% as flow limited. On average, the operators scored 27.6% of tests flow limited and 47.6% non-flow limited, but could not score 24.8%. The methods disagreed in 7.9% of cases; in 78% of these the NEP scores differed between operators. Bronchodilation reduced NEP and Δ X rs scores, with only the latter achieving significance. Averaging the operators′ NEP scores, a threshold between 24.6–30.8% of tidal volume being flow limited by NEP produced 94% agreement between methods. In conclusion, when negative expiratory pressure and Forced Oscillation Technique were both available they showed good agreement. As Forced Oscillation Technique is automatic and can measure multiple breaths over long periods, it is suitable for monitoring expiratory flow limitation continuously and identifying patients′ breathing close to the onset of expiratory flow limitation, where intermittent sampling may be unrepresentative.
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expiratory flow limitation detected by Forced Oscillation and negative expiratory pressure
European Respiratory Journal, 2006Co-Authors: Raffaele Dellaca, Nick Duffy, Pasquale Pompilio, Antonio Pedotti, Nikolaos Koulouris, Andrea Aliverti, Peter M A CalverleyAbstract:The within-breath change in reactance (Delta(rs)) measured by Forced Oscillation Technique (FOT) at 5 Hz reliably detects expiratory flow limitation in chronic obstructive pulmonary disease (COPD). The present study compared this approach to the standard negative expiratory pressure (NEP) method. In total, 21 COPD patients were studied by applying both Techniques to the same breath and in 15 patients the measurements were repeated after bronchodilator. For each patient and condition five NEP tests were performed and independently scored by three operators unaware of the FOT results. In 180 tests, FOT classified 53.3% as flow limited. On average, the operators scored 27.6% of tests flow limited and 47.6% non-flow limited, but could not score 24.8%. The methods disagreed in 7.9% of cases; in 78% of these the NEP scores differed between operators. Bronchodilation reduced NEP and DeltaX(rs) scores, with only the latter achieving significance. Averaging the operators' NEP scores, a threshold between 24.6-30.8% of tidal volume being flow limited by NEP produced 94% agreement between methods. In conclusion, when negative expiratory pressure and Forced Oscillation Technique were both available they showed good agreement. As Forced Oscillation Technique is automatic and can measure multiple breaths over long periods, it is suitable for monitoring expiratory flow limitation continuously and identifying patients' breathing close to the onset of expiratory flow limitation, where intermittent sampling may be unrepresentative.
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detection of expiratory flow limitation in copd using the Forced Oscillation Technique
European Respiratory Journal, 2004Co-Authors: Raffaele Dellaca, Antonio Pedotti, Andrea Aliverti, Pierachille Santus, N Stevenson, Stefano Centanni, Peter T Macklem, Peter M A CalverleyAbstract:Expiratory flow limitation (EFL) during tidal breathing is a major determinant of dynamic hyperinflation and exercise limitation in chronic obstructive pulmonary disease (COPD). Current methods of detecting this are either invasive or unsuited to following changes breath-by-breath. It was hypothesised that tidal flow limitation would substantially reduce the total respiratory system reactance (Xrs) during expiration, and that this reduction could be used to reliably detect if EFL was present. To test this, 5-Hz Forced Oscillations were applied at the mouth in seven healthy subjects and 15 COPD patients (mean +/- sD Forced expiratory volume in one second was 36.8 +/- 11.5% predicted) during quiet breathing. COPD breaths were analysed (n=206) and classified as flow-limited if flow decreased as alveolar pressure increased, indeterminate if flow decreased at constant alveolar pressure, or nonflow-limited. Of these, 85 breaths were flow-limited, 80 were not and 41 were indeterminate. Among other indices, mean inspiratory minus mean expiratory Xrs (deltaXrs) and minimum expiratory Xrs (Xexp,min) identified flow-limited breaths with 100% specificity and sensitivity using a threshold between 2.53-3.12 cmH2O x s x L(-1) (deltaXrs) and -7.38- -6.76 cmH2O x s x L(-1) (Xexp,min) representing 6.0% and 3.9% of the total range of values respectively. No flow-limited breaths were seen in the normal subjects by either method. Within-breath respiratory system reactance provides an accurate, reliable and noninvasive Technique to detect expiratory flow limitation in patients with chronic obstructive pulmonary disease.
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detection of expiratory flow limitation in copd using the Forced Oscillation Technique
European Respiratory Journal, 2004Co-Authors: Raffaele Dellaca, Antonio Pedotti, Andrea Aliverti, Pierachille Santus, N Stevenson, Stefano Centanni, Peter T Macklem, Peter M A CalverleyAbstract:Expiratory flow limitation (EFL) during tidal breathing is a major determinant of dynamic hyperinflation and exercise limitation in chronic obstructive pulmonary disease (COPD). Current methods of detecting this are either invasive or unsuited to following changes breath-by-breath. It was hypothesised that tidal flow limitation would substantially reduce the total respiratory system reactance (X rs ) during expiration, and that this reduction could be used to reliably detect if EFL was present. To test this, 5‐Hz Forced Oscillations were applied at the mouth in seven healthy subjects and 15 COPD patients (mean±sd Forced expiratory volume in one second was 36.8±11.5 % predicted) during quiet breathing. COPD breaths were analysed (n=206) and classified as flow-limited if flow decreased as alveolar pressure increased, indeterminate if flow decreased at constant alveolar pressure, or nonflow-limited. Of these, 85 breaths were flow-limited, 80 were not and 41 were indeterminate. Among other indices, mean inspiratory minus mean expiratory X rs (Δ X rs ) and minimum expiratory X rs (X exp,min ) identified flow-limited breaths with 100% specificity and sensitivity using a threshold between 2.53–3.12 cmH 2 O·s·L −1 (Δ X rs ) and −7.38– −6.76 cmH 2 O·s·L −1 (X exp,min ) representing 6.0% and 3.9% of the total range of values respectively. No flow-limited breaths were seen in the normal subjects by either method. Within-breath respiratory system reactance provides an accurate, reliable and noninvasive Technique to detect expiratory flow limitation in patients with chronic obstructive pulmonary disease.
Pedro Lopes De Melo - One of the best experts on this subject based on the ideXlab platform.
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early diagnosis of respiratory abnormalities in asbestos exposed workers by the Forced Oscillation Technique
PLOS ONE, 2016Co-Authors: Hermano Albuquerque De Castro, Agnaldo Jose Lopes, Pedro Lopes De MeloAbstract:Background The current reference test for the detection of respiratory abnormalities in asbestos-exposed workers is spirometry. However, spirometry has several shortcomings that greatly affect the efficacy of current asbestos control programs. The Forced Oscillation Technique (FOT) represents the current state-of-the-art Technique in the assessment of lung function. This method provides a detailed analysis of respiratory resistance and reactance at different oscillatory frequencies during tidal breathing. Here, we evaluate the FOT as an alternative method to standard spirometry for the early detection and quantification of respiratory abnormalities in asbestos-exposed workers. Methodology/Principal findings Seventy-two subjects were analyzed. The control group was composed of 33 subjects with a normal spirometric exam who had no history of smoking or pulmonary disease. Thirty-nine subjects exposed to asbestos were also studied, including 32 volunteers in radiological category 0/0 and 7 volunteers with radiological categories of 0/1 or 1/1. FOT data were interpreted using classical parameters as well as integer (InOr) and fractional-order (FrOr) modeling. The diagnostic accuracy was evaluated by investigating the area under the receiver operating characteristic curve (AUC). Exposed workers presented increased obstruction (resistance p<0.001) and a reduced compliance (p<0.001), with a predominance of obstructive changes. The FOT parameter changes were correlated with the standard pulmonary function analysis methods (R = -0.52, p<0.001). Early respiratory abnormalities were identified with a high diagnostic accuracy (AUC = 0.987) using parameters obtained from the FrOr modeling. This accuracy was significantly better than those obtained with classical (p<0.001) and InOr (p<0.001) model parameters. Conclusions The FOT improved our knowledge about the biomechanical abnormalities in workers exposed to asbestos. Additionally, a high diagnostic accuracy in the diagnosis of early respiratory abnormalities in asbestos-exposed workers was obtained. This makes the FOT particularly useful as a screening tool in the context of asbestos control and elimination. Moreover, it can facilitate epidemiological research and the longitudinal follow-up of asbestos exposure and asbestos-related diseases.
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correlations between Forced Oscillation Technique parameters and pulmonary densitovolumetry values in patients with acromegaly
Brazilian Journal of Medical and Biological Research, 2015Co-Authors: Gustavo Bittencourt Camilo, Pedro Lopes De Melo, Dequitier Carvalho Machado, Roberto Mogami, Mônica Roberto Gadelha, Leandro Kasuki, Alysson R Carvalho, Agnaldo Jose LopesAbstract:The aims of this study were to evaluate the Forced Oscillation Technique (FOT) and pulmonary densitovolumetry in acromegalic patients and to examine the correlations between these findings. In this cross-sectional study, 29 non-smoking acromegalic patients and 17 paired controls were subjected to the FOT and quantification of lung volume using multidetector computed tomography (Q-MDCT). Compared with the controls, the acromegalic patients had a higher value for resonance frequency [15.3 (10.9-19.7) vs 11.4 (9.05-17.6) Hz, P=0.023] and a lower value for mean reactance [0.32 (0.21-0.64) vs 0.49 (0.34-0.96) cm H2O/L/s2, P=0.005]. In inspiratory Q-MDCT, the acromegalic patients had higher percentages of total lung volume (TLV) for nonaerated and poorly aerated areas [0.42% (0.30-0.51%) vs 0.25% (0.20-0.32%), P=0.039 and 3.25% (2.48-3.46%) vs 1.70% (1.45-2.15%), P=0.001, respectively]. Furthermore, the acromegalic patients had higher values for total lung mass in both inspiratory and expiratory Q-MDCT [821 (635-923) vs 696 (599-769) g, P=0.021 and 844 (650-945) vs 637 (536-736) g, P=0.009, respectively]. In inspiratory Q-MDCT, TLV showed significant correlations with all FOT parameters. The TLV of hyperaerated areas showed significant correlations with intercept resistance (rs=−0.602, P<0.001) and mean resistance (rs=−0.580, P<0.001). These data showed that acromegalic patients have increased amounts of lung tissue as well as nonaerated and poorly aerated areas. Functionally, there was a loss of homogeneity of the respiratory system. Moreover, there were correlations between the structural and functional findings of the respiratory system, consistent with the pathophysiology of the disease.
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on the respiratory mechanics measured by Forced Oscillation Technique in patients with systemic sclerosis
PLOS ONE, 2013Co-Authors: Ingrid Almeida Miranda, Alvaro Camilo Dias Faria, Jose Manoel Jansen, Agnaldo Jose Lopes, Pedro Lopes De MeloAbstract:Background Pulmonary complications are the most common cause of death and morbidity in systemic sclerosis (SSc). The Forced Oscillation Technique (FOT) offers a simple and detailed approach to investigate the mechanical properties of the respiratory system. We hypothesized that SSc may introduce changes in the resistive and reactive properties of the respiratory system, and that FOT may help the diagnosis of these abnormalities. Methodology/Principal Findings We tested these hypotheses in controls (n = 30) and patients with abnormalities classified using spirometry (n = 52) and pulmonary volumes (n = 29). Resistive data were interpreted with the zero-intercept resistance (Ri) and the slope of the resistance (S) as a function of frequency. Reactance changes were evaluated by the mean reactance between 4 and 32 Hz (Xm) and the dynamic compliance (Crs,dyn). The mechanical load was evaluated using the absolute value of the impedance in 4 Hz (Z4Hz). A compartmental model was used to obtain central (R) and peripheral (Rp) resistances, and alveolar compliance (C). The clinical usefulness was evaluated by investigating the area under the receiver operating characteristic curve (AUC). The presence of expiratory flow limitation (EFL) was also evaluated. For the groups classified using spirometry, SSc resulted in increased values in Ri, R, Rp and Z4Hz (p 0.90). In groups classified by pulmonary volume, SSc resulted in reductions in S, Xm, C and Crs,dyn (p 0.80). It was also observed that EFL is not common in patients with SSc. Conclusions/Significance This study provides evidence that the respiratory resistance and reactance are changed in SSc. This analysis provides a useful description that is of particular significance for understanding respiratory pathophysiology and to ease the diagnosis of respiratory abnormalities in these patients.
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Forced Oscillation Technique in the detection of smoking induced respiratory alterations diagnostic accuracy and comparison with spirometry
Clinics, 2010Co-Authors: Alvaro Camilo Dias Faria, A A Costa, Jose Manoel Jansen, Agnaldo Jose Lopes, Pedro Lopes De MeloAbstract:INTRODUCTION: Detection of smoking effects is of utmost importance in the prevention of cigarette-induced chronic airway obstruction. The Forced Oscillation Technique offers a simple and detailed approach to investigate the mechanical properties of the respiratory system. However, there have been no data concerning the use of the Forced Oscillation Technique to evaluate respiratory mechanics in groups with different degrees of tobacco consumption. OBJECTIVES: (1) to evaluate the ability of the Forced Oscillation Technique to detect smoking-induced respiratory alterations, with special emphasis on early alterations; and (2) to compare the diagnostic accuracy of the Forced Oscillation Technique and spirometric parameters. METHODS: One hundred and seventy subjects were divided into five groups according to the number of pack-years smoked: four groups of smokers classified as 60 pack-years and a control group. The four groups of smokers were compared with the control group using receiver operating characteristic (ROC) curves. RESULTS: The early adverse effects of smoking in the group with 60 pack-years, the diagnostic performance of the Forced Oscillation Technique was similar to that observed with spirometry. CONCLUSIONS: This study revealed that Forced Oscillation Technique parameters were able to detect early smoking-induced respiratory involvement when pathologic changes are still potentially reversible. These findings support the use of the Forced Oscillation Technique as a versatile clinical diagnostic tool in helping with chronic obstructive lung disease prevention, diagnosis, and treatment.
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evaluating the Forced Oscillation Technique in the detection of early smoking induced respiratory changes
Biomedical Engineering Online, 2009Co-Authors: Alvaro Camilo Dias Faria, Jose Manoel Jansen, Agnaldo Jose Lopes, Pedro Lopes De MeloAbstract:Early detection of the effects of smoking is of the utmost importance in the prevention of chronic obstructive pulmonary disease (COPD). The Forced Oscillation Technique (FOT) is easy to perform since it requires only tidal breathing and offers a detailed approach to investigate the mechanical properties of the respiratory system. The FOT was recently suggested as an attractive alternative for diagnosing initial obstruction in COPD, which may be helpful in detecting COPD in its initial phases. Thus, the purpose of this study was twofold: (1) to evaluate the ability of FOT to detect early smoking-induced respiratory alterations; and (2) to compare the sensitivity of FOT with spirometry in a sample of low tobacco-dose subjects. Results from a group of 28 smokers with a tobacco consumption of 11.2 ± 7.3 pack-years were compared with a control group formed by 28 healthy subjects using receiver operating characteristic (ROC) curves and a questionnaire as a gold standard. The early adverse effects of smoking were adequately detected by the absolute value of the respiratory impedance (Z4Hz), the intercept resistance (R0), and the respiratory system dynamic compliance (Crs, dyn). Z4Hz was the most accurate parameter (Se = 75%, Sp = 75%), followed by R0 and Crs, dyn. The performances of the FOT parameters in the detection of the early effects of smoking were higher than that of spirometry (p < 0.05). This study shows that FOT can be used to detect early smoking-induced respiratory changes while these pathologic changes are still potentially reversible. These findings support the use of FOT as a versatile clinical diagnostic tool in aiding COPD prevention and treatment.