Role of Impulse Oscillometry in Assessing Asthma Control in Children

ABSTRACT

Background: Impulse oscillometry is an effort-independenttechnique of assessment of airway resistance and reactance, andcan be performed in children unable to complete spirometry.Objective: To evaluate the utility of impulse oscillometry andspirometry for assessing asthma control in children.Study design: Prospective cohort study.Participants: Children aged 5-15 years, with mild to severepersistent asthma.Intervention On each 3-monthly follow-up visit, clinicalassessment, classification of control of asthma, impulseoscillometry and spirometry were performed.Outcome: Utility of impulse oscillometry parameters [impedance(Z5), resistance (R5), reactance (X5) at 5 Hz, and R5-20(resistance at 20Hz -5Hz) (% predicted), and area of reactance(AX, actual values)] and FEV1 (% predicted) to discriminatebetween controlled and uncontrolled asthma was assessed byreceiver operating characteristic (ROC) curve. Association ofFEV1 and impulse oscillometry parameters over time withcontrolled asthma was evaluated by generalized estimatingequation model.Results: Number of visits in 256 children [mean (SD) age, 100(41.6) mo; boys 198 (77.3%)], where both impulse oscillometryand spirometry were performed was 2616; symptoms werecontrolled in 48.9% visits. Area under the curve fordiscrimination between controlled and uncontrolled asthma byFEV1, AX, R5-20, Z5, R5, and X5 were 0.58, 0.55, 0.55, 0.52,0.52 and 0.52, respectively. FEV1 [OR (95% CI) 1.02 (1.01-1.03)]and AX [OR (95% CI) 0.88 (0.81-0.97)] measured over theduration of follow-up were significantly associated withcontrolled asthma.Conclusion: Spirometry and impulse oscillometry parametersare comparable in ascertaining controlled asthma. Impulseoscillometry being less effort-dependent may be performed formonitoring control of childhood asthma, especially in youngerchildren.