Application of impulse oscillometry in the measurement for childhood bronchial hyperresponsiveness / 中华实用儿科临床杂志

ABSTRACT

Objective To explore the effectiveness of impulse oscillometry(IOS)in airway responsiveness measurement and to find out the positive threshold of IOS for asthma diagnosis. Methods Seventy-nine children aged 6-14 years who had suspicious asthma,were recruited into the study. The positive criteria of the methacholine bron-chial provocation test was a 20％ reduction in forced expiratory volume in the first second (FEV 1 )compared to base-line. Simultaneously measured changes in various parameters of IOS,including resonant frequency(Fres),impedance at 5 Hz(Zrs),resistances at 5 and 20 Hz(R5,R20),reactance at 5 Hz(X5),and area of reactance(AX). The results of the challenge test were divided into positive and negative groups according to the pulmonary ventilation function me-thod. The differences between the 2 groups of IOS parameters before and after the challenge test,and the correlation be-tween the change rate of FEV1 and the change rate of IOS parameters were compared,and the positive judgment criteria of IOS parameters in the determination of respiratory responsiveness were determined. Results The positive group of bronchial provocation test had 37 patients and negative group had 42 patients. There was no significant difference in the basic values of parameters between the positive group and the negative group (all P > 0. 05). Changes in Zrs,R5,X5 of IOS were correlated with changes in FEV1 (r = 0. 374,0. 310,0. 449,all P < 0. 05). By single factor analysis,the area under the receiver operating characteristic(ROC)carve (AUC)showedbasic value of Zrs increased by 45. 85％,R5 increased by 45. 72％,X5 increased by 80. 74％ respectively compared to the baseline showed the optimal combination of sensitivity and specificity. In multivariate Logistic regression models,when Zrs and R5 were combined to measure the airway responsiveness,the sensitivity and specificity were 73. 0％ and 81. 0％,respectively. Conclusions IOS and spirometry can be used to determine airway responsiveness in children during methacholine bronchial challenge. Zrs≥45. 85％,or R5≥45. 72％,or X5≥80. 74％,or Zrs and R5 of multiple regression formula can be used as the positive criteria for young children with airway heperresponsiveness,the combination of Zrs and R5 has higher sensitivity and specificity.