Forced Oscillations Technique During a Metacholine Test in Children

This study uses a breathing measurement technique called forced oscillations technique (FOT) during a standard asthma-provocation test (methacholine challenge) in children. The methacholine test checks how reactive the airways are, and FOT offers a non-invasive way to detect early airway changes. The goal is to see whether FOT can provide additional useful information about lung function in children, potentially improving asthma diagnosis. **You may be eligible if...** - Your child is between 6 and 16 years old - They have lung function above 60% predicted (FEV1 > 60%) - They have been referred for a methacholine bronchial reactivity test - They have been off inhaled corticosteroids for at least 3 weeks - The child and at least one parent/guardian have given oral consent **You may NOT be eligible if...** - Your child has used a short-acting inhaler (reliever) in the last 6 hours, or a long-acting inhaler in the past 36 hours - They have had a respiratory tract infection in the last 3 weeks - They have epilepsy under active treatment - They are enrolled in another study that could affect breathing test results Talk to your doctor to see if this trial is right for you.