Exhaled Breath Condensate as a Measure of Airway Inflammation in Children With Asthma

The onset of asthma is often during childhood, and when the child is atopic, it is more likely to persist into adulthood. Diseases such as asthma have a higher prevalence in childhood; and management that alters the morbidity of allergic disease in children may impact disease outcomes in future years.

Asthma is the most prevalent chronic disease in childhood and accounts for the highest rate of hospitalizations in the ages between 0-4 years. Unfortunately, there are few noninvasive objective measurements of pulmonary health in children. Current techniques include determination of peak flow, spirometry, and measurement of nitric oxide (NO). Bronchial inflammation is a central feature of asthma and anti-inflammatory therapy is the mainstay of treatment. Expired NO (eNO) has been shown to correlate with bronchial inflammation. However, the collection of NO has only been available in research settings due to the limitations of collection and analysis. In contrast, exhaled breath condensate (EBC) is easily obtained and pH analysis technically simple.

Determination of pH in EBC is a novel, non-invasive technique in clinical study as a means to evaluate the severity of pulmonary inflammation. In the protocol described, we will evaluate the utility of EBC in the measurement of airway disease in 60 children with asthma and compare them to 30 healthy cohorts in the same age range. We will determine if EBC pH is reflective of the degree of morbidity in children by correlating measurements with known parameters of disease including: 1) number of hospitalizations, 2) absenteeism from school, 3) number of asthma exacerbations, 4) loss of work days (if applicable), 5) extent of rescue medication usage, 6) spirometry to evaluate obstruction, and 7) NO as a measurement of inflammation.

Subjects will be evaluated and then categorized based on the National Asthma Education and Prevention Program (NAEPP) guidelines. We will measure the pH from EBC in children age 6 to less than 18 years of age and compare findings to clinical data, spirometry, and expired NO. In this way, we will determine if EBC is a potentially useful non-invasive measurement of airway disease. It is hoped that measurements of EBC will be helpful in identifying those children in which the addition of an anti-inflammatory medication is appropriate. We will also attempt to measure inflammatory mediators to determine if they can be used to assess inflammation.

This method may also be useful in detecting airway inflammation due to an infectious agent before a systemic reaction (fever, respiratory distress, or cough) is apparent in children with various immunodeficiency diseases such as chronic granulomatous disease (CGD), recurrent respiratory infections without a defined host defect (RIND), or Job's syndrome.

We will recruit 30 healthy control children in the same age range to compare the EBC pH values in children without allergic or other chronic pulmonary diseases. In addition, we will recruit 30 children (10 in each group) with CGD, RIND, and Job's to compare exhaled breath condensate pH and exhaled nitric oxide values to those from children with allergic airway inflammation to determine if these methods are useful for early diagnosis of infectious airway inflammation.