Evaluating Asthma Severity Using Forced Oscillation Technique: A Non-Invasive Insight Into Pulmonary Impedance
Keywords:
Bronchial asthma Forced Oscillation Technique Pulmonary impedance Airway resistance Reactance Asthma severity Non-invasive lung function test.Abstract
Background: Bronchial asthma is a chronic inflammatory respiratory disorder characterized by variable airflow limitation and airway hyperresponsiveness. Accurate assessment of disease severity is crucial for optimal management. Conventional pulmonary function tests (PFTs) such as spirometry are effort-dependent and may be challenging for certain populations. The Forced Oscillation Technique (FOT) offers a non-invasive, effort-independent alternative for evaluating respiratory mechanics, particularly airway resistance and reactance.
Aims: To evaluate and compare the Pulmonary Impedance in Different Severity Stages of Bronchial Asthma using Forced Oscillation Technique in a Tertiary Hospital.
Materials and Methods: A hospital-based analytical cross-sectional study was conducted in the Department of Respiratory Medicine, Adesh Institute of Medical Sciences and Research (AIMSR), Bathinda, involving 150 patients aged 18–65 years diagnosed with bronchial asthma. Participants were stratified into mild, moderate, and severe asthma groups based on NAEPP-EPR 3 guidelines. FOT parameters—resistance at 5 Hz (Rrs5), resistance at 19 Hz (Rrs19), difference (Rrs5–Rrs19), reactance at 5 Hz (Xrs5), and impedance at 5 Hz (Zrs5)—were recorded using the Resmon Pro device. Statistical analysis was performed using SPSS v25.0, with p < 0.05 considered significant.
Results: The mean age of participants was 41.46 ± 13.9 years, with a female
predominance (60%). Allergies (51.3%) and dust/fume exposure (50.7%) were prevalent risk factors. FOT parameters demonstrated a significant correlation with asthma severity. Rrs5, Rrs19, Rrs5–Rrs19, and Zrs5 values increased progressively from mild to severe asthma (p < 0.01), while Xrs5 became more negative with increasing severity (p = 0.043), indicating reduced lung compliance.
Conclusion: FOT effectively reflects changes in airway resistance and reactance across varying asthma severities, offering a reliable and non-invasive tool for asthma evaluation and monitoring, especially in patients unable to perform traditional spirometry.
