Forced oscillation, integer and fractional-order modeling in asthma

Faria, Alvaro Camilo Dias; Veiga, Juliana; Lopes, Agnaldo José; Melo, Pedro Lopes de

doi:10.1016/j.cmpb.2016.02.010

Cited by 31 publications

(49 citation statements)

References 54 publications

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“…In contrast with previous studies in obstructive patients with COPD [62] and asthma [37], α values were reduced in the exposed group (Fig 7B). This may be associated with the fact that the real part of the impedance in the exposed subjects decreased with frequency (Fig 3A).…”

Section: Discussioncontrasting

confidence: 99%

“…The increased values of G in the exposed volunteers (Fig 7E) are consistent with previous experimental findings in patients with asthma [37]. G is a measure of the energy dissipation in the respiratory tissues [59].…”

Section: Discussionsupporting

confidence: 90%

“…Recent studies from our research group have provided evidence that FrOr models may facilitate the early identification of mild airway obstruction and lung abnormalities in adults with asthma [37]. To evaluate the sensitivity of the fractional-order parameters and their possible use in a classification strategy for asbestos-exposed workers, we used the most sensitive model in the cited previous study [37].…”

Section: Methodsmentioning

confidence: 99%

“…To evaluate the sensitivity of the fractional-order parameters and their possible use in a classification strategy for asbestos-exposed workers, we used the most sensitive model in the cited previous study [37]. This model includes a frequency-dependent inertance L and a tissue component described as a constant-phase impedance: where 0 ≤ α ≤ 1, C is the compliance, and 0 ≤ β ≤ 1.…”

Section: Methodsmentioning

confidence: 99%

“…In addition, these model parameters could improve the diagnosis of respiratory abnormalities. Recently, these models contributed to an increase in the diagnostic accuracy of mild asthma [37] and adult patients with cystic fibrosis [38]. …”

Section: Introductionmentioning

confidence: 99%

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Early Diagnosis of Respiratory Abnormalities in Asbestos-Exposed Workers by the Forced Oscillation Technique

et al. 2016

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BackgroundThe 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 findingsSeventy-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.ConclusionsThe 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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Section: Discussioncontrasting

confidence: 99%

Section: Discussionsupporting

confidence: 90%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Early Diagnosis of Respiratory Abnormalities in Asbestos-Exposed Workers by the Forced Oscillation Technique

et al. 2016

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Generalization of shadow filters in fractional domain

Varshney

Pandey

2021

Circuit Theory & Apps

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This work is intended to generalize the design of shadow filters to the fractional-order domain. Shadow filters, in integer-order domain, introduced by Lakys and Fabre, consist of an external amplifier in the feedback loop of the basic filter cell and by varying the gain of this amplifier the parameters of the resulting filter are modified without disturbing the active and passive components of the filter itself. In particular, we consider here the case where a basic 2α order filter is constructed using two fractional-order capacitors both of the same order α. Mathematical formulations are drafted for pole frequency and pole quality factor for different feedback signals with various cases of stability and demonstrated using MATLAB simulations. Functional verification of the proposed theory is verified using an active filter example, designed around operational transconductance amplifier (OTA), through SPICE using 180 nm CMOS technology model parameters.

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