Assessment of bronchial obstruction and its reversibility by shape indexes of the flow-volume loop in asthmatic children - Archive ouverte HAL Access content directly
Master Thesis Year : 2020

Assessment of bronchial obstruction and its reversibility by shape indexes of the flow-volume loop in asthmatic children

Evaluation de l'obstruction bronchique et de sa réversibilité par la mesure des indices d'incurvation de la boucle débit volume chez l'enfant asthmatique

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Abstract

BACKGROUND: Asthma assessment by spirometry is challenging in children as forced expiratory volume in one second (FEV1) is frequently normal at baseline. Bronchodilator (BD) responsiveness may reinforce asthma diagnosis but FEV1 sensitivity is controversial. Ventilation inhomogeneities, an early sign of airway obstruction, are described by the upward concavity of the descending limb of the forced expiratory flow-volume loop (FVL),not detected by FEV1. The aim of this study was to test the diagnosis ability of FVL curvature indexes as β-angle and ratio of forced expiratory flow at 50% of the forced vital capacity to peak expiratory flow (FEF50/PEF) to separate asthmatics from healthy children in comparison to FEV1 at baseline and after BD. METHODS: 72 asthmatic and 29 age-matched healthy children aged 8 to 11 years were prospectively recruited. Children performed forced spirometry at baseline and after BD inhalation. β-angle and FEF50/PEF were computed. Parameters were expressed at baseline as z-scores and after BD as percentage of change reported to baseline value (Δ%). To test the diagnostic capacity of each parameter, receiver operating characteristic curves were generated and sensitivity and specificity at respective thresholds reported. RESULTS: zβ-angle and zFEF50/PEF were significantly smaller and Δ%FEF50/PEF significantly larger in asthmatics than controls (p≤0.03) with no difference for Δ%β-angle. zβ-angle and zFEF50/PEF exhibited slightly better sensitivity, 0.58, respectively 0.60, than zFEV1, 0.50, and similar specificity, 0.72. Δ%β-angle showed higher sensitivity, 0.72, vs Δ%FEV1, 0.42, but low specificity, 0.52, vs Δ%FEV1, 0.86, to differentiate the two populations. When combining shape indexes with FEV1, best sensitivity was obtained for zβ-angle or zFEF50/PEF + zFEV1, 0.88 for both, while best specificity for Δ%FEF50/PEF + Δ%FEV1, 0.83. CONCLUSIONS: Shape indexes and FEV1 at baseline and their response to BD showed different patterns of sensitivity and specificity, being complementary. Quantitative and qualitative assessment of FVL may improve the ability to detect an airway obstruction, FEV1 reflecting more proximal while shape indexes peripheral, distal bronchial obstruction.
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Dates and versions

hal-03298103 , version 1 (23-07-2021)

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  • HAL Id : hal-03298103 , version 1

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Amaury Berrier. Evaluation de l'obstruction bronchique et de sa réversibilité par la mesure des indices d'incurvation de la boucle débit volume chez l'enfant asthmatique. Médecine humaine et pathologie. 2020. ⟨hal-03298103⟩
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