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Low Frequency Forced Oscillation Lung Function Test Can Distinguish Dynamic Tissue Non-linearity in COPD Patients.

ABSTRACT: This paper introduces the use of low frequencies forced oscillation technique (FOT) in the presence of breathing signal. The hypothesis tested is to evaluate the sensitivity of FOT to various degrees of obstruction in COPD patients. The measurements were performed in the frequency range 0-2 Hz. The use of FOT to evaluate respiratory impedance has been broadly recognized and its complementary use next to standardized method as spirometry and body plethysmography has been well-documented. Typical use of FOT uses frequencies between 4-32 Hz and above. However, interesting information at frequencies below 4 Hz is related to viscoelastic properties of parenchyma. Structural changes in COPD affect viscoelastic properties and we propose to investigate the use of FOT at low frequencies with a fourth generation fan-based FOT device. The generator non-linearity introduced by the device is separated from the linear approximation of the impedance before evaluating the results on patients. Three groups of COPD obstruction, GOLD II, III, and IV are evaluated. We found significant differences in mechanical parameters (tissue damping, tissue elasticity, hysteresivity) and increased degrees of non-linear dynamic contributions in the impedance data with increasing degree of obstruction (p < 0.01). The results obtained suggest that the non-linear index correlates better with degrees of heterogeneity linked to COPD GOLD stages, than the currently used hysteresivity index. The protocol and method may prove useful to improve current diagnosis percentages for various COPD phenotypes.

SUBMITTER: Ghita M

PROVIDER: S-EPMC6877497 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Low Frequency Forced Oscillation Lung Function Test Can Distinguish Dynamic Tissue Non-linearity in COPD Patients.

Ghita Maria M Copot Dana D Ghita Mihaela M Derom Eric E Ionescu Clara C

Frontiers in physiology 20191119

This paper introduces the use of low frequencies forced oscillation technique (FOT) in the presence of breathing signal. The hypothesis tested is to evaluate the sensitivity of FOT to various degrees of obstruction in COPD patients. The measurements were performed in the frequency range 0-2 Hz. The use of FOT to evaluate respiratory impedance has been broadly recognized and its complementary use next to standardized method as spirometry and body plethysmography has been well-documented. Typical ...[more]

PMID: 31803060

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Project description:IntroductionPerforming lung function test in geriatric patients has never been an easy task. With well-established evidence indicating impaired small airway function and air trapping in patients with geriatric COPD, utilizing forced oscillation technique (FOT) as a supplementary tool may aid in the assessment of lung function in this population.AimsTo study the use of FOT in the assessment of airflow limitation and air trapping in geriatric COPD patients.Study designA cross-sectional study in a public hospital in Hong Kong. ClinicalTrials.gov ID: NCT01553812.MethodsGeriatric patients who had spirometry-diagnosed COPD were recruited, with both FOT and plethysmography performed. "Resistance" and "reactance" FOT parameters were compared to plethysmography for the assessment of air trapping and airflow limitation.ResultsIn total, 158 COPD subjects with a mean age of 71.9±0.7 years and percentage of forced expiratory volume in 1 second of 53.4±1.7 L were recruited. FOT values had a good correlation (r=0.4-0.7) to spirometric data. In general, X values (reactance) were better than R values (resistance), showing a higher correlation with spirometric data in airflow limitation (r=0.07-0.49 vs 0.61-0.67), small airway (r=0.05-0.48 vs 0.56-0.65), and lung volume (r=0.12-0.29 vs 0.43-0.49). In addition, resonance frequency (Fres) and frequency dependence (FDep) could well identify the severe type (percentage of forced expiratory volume in 1 second <50%) of COPD with high sensitivity (0.76, 0.71) and specificity (0.72, 0.64) (area under the curve: 0.8 and 0.77, respectively). Moreover, X values could stratify different severities of air trapping, while R values could not.ConclusionFOT may act as a simple and accurate tool in the assessment of severity of airflow limitation, small and central airway function, and air trapping in patients with geriatric COPD who have difficulties performing conventional lung function test. Moreover, reactance parameters were better than resistance parameters in correlation with air trapping.

Project description: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.

Project description:PurposeWe developed a method for quantifying intraoperative torsional forced ductions and validated the new test by comparing patients with oblique dysfunction and controls.DesignComparative case series.SubjectsWe studied 33 eyes with oblique dysfunction (9 with presumed congenital superior oblique palsy [SOP], 13 with acquired SOP, 7 with Brown syndrome, and 4 with inverted Brown syndrome) and 31 controls. We also studied 6 eyes after superior oblique (SO) disinsertion and 2 eyes after inferior oblique (IO) disinsertion.MethodsUnder deep general anesthesia, the 12 and 6 o'clock positions at the limbus were marked and the globe was maximally excyclorotated and incyclorotated without retroplacement until the first resistance was felt, and the angle of rotation (in degrees) was read on a Mendez ring by the surgeon. A photograph was taken in each position to be read by a masked observer.Main outcome measuresMaximal excyclorotation and maximal incyclorotation in each oblique dysfunction and in controls by both surgeon's report and photographic assessment. We duplicated the photographs to evaluate test-retest reliability and to evaluate agreement between the surgeon's assessments and the photographic assessment.ResultsSurgeon's assessment revealed greater maximal excyclorotation in eyes with presumed congenital SOP than in controls (median, 40 vs. 30 degrees). Maximal excyclorotation in eyes with acquired SOP was similar to that in controls (30 degrees in both). Eyes with Brown syndrome and inverted Brown syndrome had lower maximal excyclorotation than in controls (10 and 20 vs. 30 degrees, respectively). Maximal incyclorotation in eyes with inverted Brown syndrome was lower than in controls (12.5 vs. 30 degrees), whereas it was similar to that of controls in eyes with presumed congenital SOP, acquired SOP, and Brown syndrome (30 degrees in each condition). Median maximal excyclorotation after SO disinsertion was 62.5 degrees, and maximal incyclorotation after IO disinsertion was 60 degrees. Photographic assessment yielded findings essentially identical to the surgeon's report. Test-retest reliability of the photographic reading was excellent, and agreement between the surgeon's report and the photographic reading was also excellent (95% limits of agreement, 4.4 and 11.6; intraclass correlation coefficient, 0.97 and 0.82, respectively).ConclusionsThe new torsional forced duction test enables quantitative assessment of SO and IO tightness and laxity.

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Low Frequency Forced Oscillation Lung Function Test Can Distinguish Dynamic Tissue Non-linearity in COPD Patients.

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Low Frequency Forced Oscillation Lung Function Test Can Distinguish Dynamic Tissue Non-linearity in COPD Patients.

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