Evaluation of the Relationship Between Impulse Oscillometry and Spirometry Parameters in Children with Cystic Fibrosis

Abstract

Background: Cystic fibrosis (CF) is an autosomal recessive disease that occurs due to mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. This disease is a multiorgan disorder; however, progressive lung involvement is the main cause of morbidity and mortality in most patients. Objectives: The current study aimed to evaluate the association between Impulse Oscillometry (IOS) indices and spirometric parameters in pediatric patients with CF. Methods: In this cross-sectional study, 51 children with CF aged 6 to 18 years from Mofid Children's Hospital, Tehran, Iran in 2022 and 2023 were included. For patients who met the inclusion criteria, spirometry was carried out using the Master Screen device. In addition, each patient underwent an IOS assessment, during which the corresponding parameters — including impedance at 5 Hz (Z5), resistance at 5 Hz (R5), and area of reactance (AX) — were measured and documented. Results: The mean ± standard deviation (SD) age of the studied patients was 12.06 ± 4.31 years. Of the patients, 58.8% were male. The mean ± SD sweat test result was 81.73 ± 10.86 mmol/L. There was a slight negative correlation between the R5 and forced expiratory volume in 1 second (FEV1, R = -0.298, P = 0.034). A stronger negative correlation was observed between the R5 Index and forced expiratory volume 25 - 75 (FEV25-75, R = -0.358, P = 0.01). There was a significant inverse relationship between R5 and the ratio of FEV1/forced vital capacity (FVC, R = -0.474, P = 0.0001). Additionally, resistance at 20 Hz (R20) had a notable negative relationship with FEV25-75 (R = -0.385, P = 0.005). The highest correlation value was between R20 and FEV1/FVC (R = -0.479, P = 0.0001). Other IOS parameters had no remarkable relationship with spirometry parameters (P > 0.05). Conclusions: Given the observed correlations between certain spirometry measures and IOS parameters, IOS may serve as an alternative assessment when a patient is unable to adequately perform spirometry.