Investigation of Lung Ventilation Inhomogeneity in Pediatric Asthma

Study Overview
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Brief Summary
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The primary objective of this study is to determine if well-controlled asthmatic patients followed in subspecialty asthma clinics between the ages of 3 - 18 years can be distinguished from healthy controls using lung clearance index, a parameter from the multiple breath washout test. Also, to correlate lung clearance index with asthma sputum cell counts.

Detailed Description
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Clinical studies are underway which are examining the utility of the LCI in obstructive respiratory disease (cystic fibrosis and asthma). However, the majority of studies have examined asthmatics with ongoing evidence of reversible disease on spirometry. There is a very limited body of research comparing LCI values in well-controlled asthmatics to healthy controls. Furthermore, the type of inflammation occurring in asthma may have a different site of action, we will prospectively study whether there is a difference in LCI between eosinophilic and neutrophilic inflammation to give us an indication of whether the site of non-eosinophilic inflammation is primarily in the small airways as well.

Official Title
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Investigation of Lung Ventilation Inhomogeneity in Pediatric Asthma: Multiple Breath Washout and Asthma

Conditions
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Asthma

Intervention / Treatment
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* Drug: Sodium Chloride Inhalation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Asthma Subjects: 3 - 18 years of age at enrolment Clinically stable at enrolment Physician diagnosis of asthma and attending follow-up in the Asthma Clinic Exclusion Criteria: Asthma Subjects: Born premature (before 37 weeks gestational age) Low birth weight (less than 2.5 kilograms) History of congenital heart disease, neuromuscular disorder or bone disease History of any chronic lung disease other than asthma Respiratory infection in last three weeks Change in medication in last three weeks (including oral steroids) Current or previous history of smoking

Ages Eligible for Study
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Minimum Age: 3 Years
Maximum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Asthma Patients<br>Spirometry. Bronchodilator with Salbutamol. Induced sputum in > 10 years of age using Sodium Chloride Inhalation. Multiple Breath Washout (MBW). | Drug: Sodium Chloride Inhalation<br>* Spirometry: all subjects Plethysmography and exhaled nitric oxide: >6 years Multiple Breath Washout: Tidal breathing using a facemask <9 years or mouthpiece >9 years. Wash-in phase: gas mixture containing 4% SF6, 4% He, 21% oxygen and balance nitrogen inhaled until steady state. Bias flow stopped during expiration by removal of T-piece. Wash-out phase: patient inspires room air and exhales tracer gas until SF6 reaches <0.1%. Bronchodilator response: Bronchodilator (Salbutamol 400 mcg) to asthma subjects, spirometry and MBW repeated after 15 minutes. Induced sputum in asthma subjects >10 yrs. Post-bronchodilator spirometry, subject inhales concentrations of 3, 4 and 5% hypertonic saline for 7 minutes for 3 cycles until expectorating sputum.<br>* Other names: Salt, NaCl;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Lung Clearance Index (LCI) | Lung clearance index will be compared between healthy and asthmatic patients after they have performed Pulmonary Function Testing and Multiple Breath Washout | Day 1 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Correlation of sputum cell counts with LCI | Sputum induction for specimen collection | Day 1 | 
| Effect of bronchodilator on baseline and post-spirometry LCI |  | Day 1 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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pediatric, lung ventilation inhomogeneity