Childhood asthma: Exhaled markers of airway inflammation, asthma control score, and lung function tests

Abstract

Exhaled markers of airway inflammation become increasingly important in the management of childhood asthma. The aims of the present study are: 1) to compare exhaled markers of inflammation (nitric oxide, carbon monoxide, and acidity of breath condensate) with conventional asthma measures (lung function tests and asthma control score) in childhood asthma; and 2) to investigate the detectability of albumin, CRP, IL-6, IL-8, TNF-alpha, sICAM-1, and sTNF-R75 in the exhaled breath condensate (EBC) of asthmatic children. Thirty-two children with mild to moderate persistent asthma and healthy controls aged 6-12 years were studied. We measured exhaled NO and CO, and subsequently EBC was collected. Inflammatory mediators in EBC were measured using an enzyme-linked immunosorbent assay. Respiratory symptoms and asthma control were assessed using the asthma control questionnaire (ACQ) of Juniper et al. (Eur Respir J 1999;14:902-907). Exhaled NO showed a significant correlation with exhaled CO (r = 0.59, P < 0.05) and FEV1 (r = -0.59, P < 0.05), but not with ACQ score (r = 0.48, P = 0.06). Exhaled CO was correlated with prebronchodilator FEV1 (r = -0.45, P < 0.05), but not with asthma control (r = 0.18, P = 0.35). Acidity of EBC was significantly lower in asthmatic children than in healthy controls (P < 0.05), but did not correlate with any of the conventional asthma measures. We were not able to demonstrate the presence of CRP, IL-6, IL-8, TNF-alpha, sICAM-1, and sTNF-R75 in EBC. Albumin was found in two EBC samples of asthmatic children. We conclude that exhaled NO had a better correlation with lung function parameters and asthma control than exhaled CO and acidity of EBC, in mild to moderate persistent childhood asthma. However, exhaled NO, CO, and deaerated pH of EBC did not differ between asthmatic children and controls, possibly because of a too homogeneous and well-controlled study population. To further evaluate the clinical utility of exhaled markers in monitoring childhood asthma, more studies are required on a wider range of asthma severity, and preferably with repeated measurements of markers and of asthma control.

Exhaled Breath Condensate pH Assays

“…Normal values of gas-standardized ("CO 2 -free") EBC pH have been reported from multiple investigators and range between 7.5 and 8.1 (3,8,9,(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). In our normative database from 404 subjects, the mean pH was 7.83, and the median pH was 8.0 (12).…”

Magnesium and calcium in exhaled breath condensate of children with asthma and gastroesophageal reflux disease

“…Biomarkers are originated from lower airways, but there is the possibility of saliva, upper respiratory tract contamination. To date, changes of biochemical markers of inflammation and oxidative stress have been most extensively investigated in patients with asthma (38,39), COPD (40,41), cystic fibrosis (42,43), and lung carcinoma (44) and less extensively in other pulmonary diseases (45). There is a general opinion that profiles of different analytes in EBC could be chosen in the future to help in the differential diagnosis of pulmonary diseases (16).…”

The Clinical Utility of Fractional Exhaled Nitric Oxide (FeNO) in Asthma Management

“…85 In another study, mean FeNO values were significantly higher in patients with an ACT score <20 compared to those patients with an ACT score ≥20 (65.5 vs 27.4 ppb, p<0.001). 78 FeNO level of >47 ppb was used to indicate inflammation and uncontrolled asthma.…”