Background: Asthma has been considered a disease that predominantly involves the large airways. Today, this concept is being challenged, and increasing evidence has become available showing that abnormalities in the small airways also contribute to the clinical expression of asthma.
Objectives: To provide an overview of impulse oscillometry and its application to the evaluation of children with diseases of the airways and detection of bronchodilator response regarding the levels of asthma control in asthmatic children.
Methods: this study was done on 50 asthmatic patients diagnosed according to the clinical manifestations and pulmonary functions. Children performed IOS and spirometry before and after 200 mcg salbutamol inhalation. Because of the possible effects of forced expiratory maneuvers on the bronchial motor tonus, first IOS, and then spirometry was performed. This study was carried out at Pediatric Chest Clinic, Children's Hospital, Ain Shams University. The asthmatic patients were recruited from both Al-Hussein and Ain shams pulmonology and allergy outpatient clinics, from December 2016 to November 2017.
Results: this study showed that the prevalence of small airways dysfunction when utilizing a spirometric cut-off value (i.e<60% in MEF25-75) was 64% and when employing IOS cut-off value (>0.1 kPa/L/s for R5-R20, >15 Hz for Fres) a prevalence of 82% and 78% were observed respectivelyand showed that the best index with +ve BDR was X5 which detected 63.6% of controlled , 52.6% of partly controlled and 66.7% of uncontrolled asthmatic patients compared with 40.9%, 63.2% and 66.7% for the same patients respectively when assessed by spirometry using ∆ FEV1%. Statistical analysis was done by using IBM SPSS software package version 20.0.
Conclusion: IOS is a noninvasive, rapid and safe technique that may be used to diagnose, evaluate, and determine treatment response in those with asthma.