ABSTRACT
Objective:To compare and analyze the effects of impulse oscillometry (IOS) and pulmonary function test (PFT) in the assessment of asthma control in children.Methods:A cross-sectional study of 323 children with bronchial asthma who visited the outpatient pediatric clinic of Shandong Provincial Hospital Affiliated to Shandong First Medical University from March to December 2020 was conducted.The patients were divided into the control group (123 cases) and the uncontrolled group (200 cases) according to the Childhood Asthma Control Test (C-ACT) score.In both groups, PFT and IOS were performed.The PFT test included the forced expiratory volume in one second (FEV 1), force expiratory volume in one second/forced vital capacity (FEV 1/FVC), peak expiratory flow (PEF), the instantaneous forced expiratory flow at 50% of forced vital capacity (FEF 50), the instantaneous forced expiratory flow at 75% of forced vital capacity (FEF 75), and maximum mid expiratory flow (MMEF). In the IOS test, the total respiratory impedance at 5 Hz (Z5), respiratory resistance at 5 Hz (R5), respiratory resistance at 20 Hz (R20), reactance at 5 Hz (X5), respiratory resistance at 5 Hz-respiratory resistance at 20 Hz (R5-R20), reactance area (AX), and resonance frequency (Fres) were measured.The data obtained were analyzed statistically using SPSS 25.0 software. ANOVA or Mann- Whitney U rank-sum test was used to compare data between groups.Receiver′s operating characteristic (ROC) curves were drawn to determine the predictive value of PFT and IOS parameters for uncontrolled asthma. Results:(1) According to the comparison results of PFT indexes between the two groups of children with asthma, the levels of FEV 1, FEV 1/FVC, PEF, FEF 50, FEF 75, MMEF in the control group were all higher than those in the uncontrolled group [(104.41±12.38)% vs.(98.89±16.61)%, 100.50 (94.40, 103.50)% vs.96.00 (89.83, 101.88)%, (100.29±15.31)% vs.(93.19±18.43)%, 85.60(70.60, 96.60)% vs.72.35 (57.08, 91.10)%, 67.20 (53.60, 81.70)% vs.56.80 (41.10, 74.73)%, 80.70 (66.80, 95.10)% vs.69.50 (54.03, 90.05)%] (all P<0.01). (2) According to the comparison results of IOS indices between the two groups, the levels of Z5, R5, R20, R5-R20, X5, AX and Fres in the control group were lower than those in the uncontrolled group {68.58 (63.29, 77.43)% vs.81.27(70.93, 91.96)%, 68.91(62.94, 77.60)% vs.80.61 (70.02, 89.29)%, 75.78 (67.50, 87.55)% vs.82.97 (71.50, 95.50)%, 0.51 (0.43, 0.59) [kPa/(L·S)] vs.0.62 (0.53, 0.74) [kPa/(L·S)], 69.31 (59.93, 79.14)% vs.86.48 (70.00, 102.48)%, 1.11 (0.76, 1.60) kPa/L vs.2.14 (1.42, 2.85) kPa/L, 18.21 (16.06, 19.56) Hz vs.20.56 (18.92, 22.81) Hz} (all P<0.01). (3) In the control group, 31 children (25.20%) had pulmonary dysfunction.(4) In the uncontrolled group, 95 children (47.50%) had pulmonary ventilation dysfunction.Only 20 children (10.00%) had a R5 larger than 120% of the predicted value and/or a R20 larger than 120% of the predicted value.(5) According to the ROC analysis results of the IOS indices for predicting asthma exacerbations, all of the areas under the ROC (AUC) of Z5, R5, R5-R20, X5, AX and Fres were greater than 0.7.AX had the highest value in predicting asthma exacerbations (AUC=0.785, 95% CI: 0.735-0.835), with sensitivity of 78.50% and specificity of 64.20%.All of the AUCs of PFT indices were smaller than 0.7.FEF 50 and MMEF had the largest AUC. Conclusions:PFT and IOS have good sensitivity in evaluating the level of asthma control in children, and IOS has good value in predicting asthma exacerbations.AX has the highest predictive value for asthma exacerbations.Asthma control levels of children should be evaluated using not only subjective (such as C-ACT score) but also objective (e.g.PFT, IOS) indices.