Background: when using oscillometry, theoretical reasons support the use of admittance (Y) instead of impedance (Z) for assessing changes in lung mechanics within the same patient (Farré, ERJ,2022), as changes in Y are not affected by upper airway shunt. The current study aims to compare changes in both Y and Z with changes in spirometry due to bronchodilation (BD) in children with persistent asthma. Methods: we retrospectively analyzed data collected on children (6–12 y). Oscillometry (RESMON PRO FULL, Restech srl, Italy) followed by spirometry was performed pre and post 400 mcg salbutamol. A positive response to BD was defined as an increase in FVC or FEV1 >10%predicted (Stanojevic, ERJ, 2022). We computed the AUC of the ROC curve considering absolute and relative (ºseline) changes of oscillometry parameters at 5Hz from Z (module, resistance (R5) and reactance (X5)) and Y (module, conductance (G5) and susceptance (B5)). Results: we included 56 children (Table 1), with 17 showing a positive response to BD. Conclusion: in these subjects with normal baseline FEV1, the agreement with spirometry was similar using Y or Z. The impact of using Y should be evaluated in smaller or more obstructed children, where the impact of the upper airway shunt is higher.
Response to bronchodilation in children by oscillatory impedance and admittance
Ferrante, GiulianaMembro del Collaboration Group
;Venditto, LauraMembro del Collaboration Group
;Piazza, MicheleMembro del Collaboration Group
;Tenero, LauraMembro del Collaboration Group
;Zaffanello, MarcoMembro del Collaboration Group
;Piacentini, GiorgioSupervision
2023-01-01
Abstract
Background: when using oscillometry, theoretical reasons support the use of admittance (Y) instead of impedance (Z) for assessing changes in lung mechanics within the same patient (Farré, ERJ,2022), as changes in Y are not affected by upper airway shunt. The current study aims to compare changes in both Y and Z with changes in spirometry due to bronchodilation (BD) in children with persistent asthma. Methods: we retrospectively analyzed data collected on children (6–12 y). Oscillometry (RESMON PRO FULL, Restech srl, Italy) followed by spirometry was performed pre and post 400 mcg salbutamol. A positive response to BD was defined as an increase in FVC or FEV1 >10%predicted (Stanojevic, ERJ, 2022). We computed the AUC of the ROC curve considering absolute and relative (ºseline) changes of oscillometry parameters at 5Hz from Z (module, resistance (R5) and reactance (X5)) and Y (module, conductance (G5) and susceptance (B5)). Results: we included 56 children (Table 1), with 17 showing a positive response to BD. Conclusion: in these subjects with normal baseline FEV1, the agreement with spirometry was similar using Y or Z. The impact of using Y should be evaluated in smaller or more obstructed children, where the impact of the upper airway shunt is higher.
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