Volatile organic compounds in the exhaled breath of young patients with cystic fibrosis

¹ Dept. of Paediatrics, University of Technology (RWTH) Medical Center, Aachen, Germany
² Institute of Chemistry and Dynamics of the Geosphere, Division II: Troposphere
³ Institute of Chemistry and Dynamics of the Geosphere, Division II: Troposphere; and Central Library, Research Center Jülich, Germany

^* To whom correspondence should be addressed. E-mail: Barker{at}rwth-aachen.de.

	Abstract

Inflammatory mediators in the exhaled breath are receiving growing medical interest as non-invasive disease markers. Volatile organic compounds have been investigated in this context, but clinical information and methodological standards are limited.

We measured the levels of ethane, propane, n-pentane, methanol, ethanol, 2-propanol, acetone, isoprene, benzene, toluene, dimethylsulfide and limonene in repeated breath samples from 20 cystic fibrosis patients and 20 healthy controls (age 8-29 years). Three end-exhaled and one ambient air sample were collected per person and analysed on a customised gas chromatography system.

Intra-subject coefficients of variation ranged between 9-34%, and hydrocarbon breath levels were influenced by their inspired concentrations. The alveolar gradient for pentane was higher in cystic fibrosis patients than in healthy controls (0.36 vs. 0.21 ppb, p=0.04) and inversely proportional to FEV₁ (r=-0.62, p=0.004), highest values were observed in patients with pulmonary exacerbations (0.73 vs. 0.24 ppb, p=0.006). Cystic fibrosis patients also exhibited a lower output of dimethylsulfide (3.9 vs. 7.6 ppb, p=0.003). Group differences were not significant for ethane and the remaining substances.

We conclude that chemical breath analysis for volatile organic compounds is feasible and may hold potential for the non-invasive diagnosis and follow-up of inflammatory processes in cystic fibrosis lung disease.