Capillary electrophoretic analysis of exhaled breath condensate in non-invasive diagnosis of
                                  gastroesophageal reflux disease

   Pavol Ďurč^a,c, Štefan Konečný^d, Jiří Dolina^d, Martina Doubková^e, Jana Skřičková^e, Dagmar
   Kindlová^e, Eva Pokojová^e, Júlia Lačná^a,c, Michal Greguš^a,c, František Foret^a,b, and Petr
                                            Kubáň^a,b,c

   ^a Department of Bioanalytical Instrumentation, CEITEC Masaryk University, 602 00 Brno, Czech
                                             Republic
^b Department of Bioanalytical Instrumentation, Institute of Analytical Chemistry, Czech Academy of
                               Sciences, 602 00 Brno, Czech Republic
            ^c Department of Chemistry, Masaryk University, 611 37 Brno, Czech Republic
  ^d Department of Gastroenterology and Internal Medicine, University Hospital Brno, 625 00 Brno,
                                          Czech Republic
^e Department of Respiratory Diseases and TB, University Hospital Brno, 625 00 Brno, Czech Republic

Gastroesophageal reflux disease (GERD) is a disease caused by backflow of gastric contents into the
esophagus due to the failure of physiological antireflux mechanisms and can lead to symptoms such
as chronic cough, globus sensation, laryngitis, pharyngitis, rhinosinusitis, otitis media,
bronchial asthma, COPD, sleep apnea and noncardiac chest pain. Currently there is no suitable,
non-invasive diagnostic method applicable for GERD in clinical practice.

In this work, exhaled breath condensate (EBC) was tested as a non-invasive sample for GERD
diagnosis. The EBC samples from three groups if individuals were analyzed. Two groups of patients
with GERD (a group having a weakly acid reflux and a group having an acid reflux) and a group of
healthy volunteers. pH values of EBC samples were measured. Capillary electrophoresis with
contactless conductometric detection was used for analysis of ionic content of EBC. Additionally,
pepsin was measured in saliva samples using commercially available lateral flow device.

We have identified statistically significant differences in pH and content of several ions
(inorganic anions, organic acids) in EBC of the studied groups. The analysis of pepsin did not
enable to differentiate among the groups of healthy and weakly acidic reflux. The identified ions
and pH measurement could serve as potential biomarkers for distinguishing the patients with GERD
and healthy individuals, without a need for invasive measurements, as is current clinical practice.

Acknowledgment

This research was carried out under the project CEITEC 2020 (LQ1601) with financial support from
the Ministry of Education, Youth and Sports of the Czech Republic under the National Sustainability
Programme II. The authors acknowledge the financial support from the Institutional support RVO:
68081715. This work was supported by Ministry of Health of the Czech Republic, grant nr. 17-31945A.