Chicago Classification Normative Metrics in a Healthy Russian Cohort According to High-resolution Esophageal Manometry

Inclusion Criteria (all points are necessary for inclusion): * Willingness to participate on the basis of signed informed consent form; * Patients of both sexes, aged 18 to 65 years inclusive; * Permanent residence in the Russian Federation; * Absence of esophageal diseases, confirmed by the results of clinical and instrumental examination * Ability to follow instructions during high-resolution esophageal manometry procedure Exclusion Criteria (patient is not eligible when at least one exclusion criterion is met): * diseases of the esophagus (any condition on the basis of clinical and / or instrumental examination, including: complaints of heartburn, belching, difficulty to swallow solid and/or liquid food; * any surgical intervention on the gastrointestinal tract and / or chest organs in medical history; * solid organ transplantation in medical history with the exception of a corneal transplant and surgery to replace the lens of the eye; * any oncology of any localization except for skin cancer in situ in the medical history; * any decompensated diseases of any organs and systems, which, in the opinion of the researcher, makes it impossible to carry out the procedure of esophageal manometry of high resolution or if the procedure may cause the risk of deterioration of the patient's condition; * any condition, clinical and laboratory signs of alcohol abuse (abuse will be assessed in the case of male subjects consuming more than 30 g of pure alcohol per day and using more than 20 g of pure alcohol per day by female subjects; * any illegal drug use, current or past; * use of concomitant medications that can affect esophageal motility including, but not limited to: calcium channel blockers, metoclopramide, m-cholinolytics, domperidone, erythromycin, nitrates, tricyclic antidepressants, opiates, beta-blockers, beta-adrenomimetics, alcohol. The duration of the period of non-use of these drugs should provide sufficient time for the complete cessation of their pharmacological action, but not less than two half-life. * pregnant or breastfeeding women * any condition making impossible to perform high resolution esophageal manometry (previously known poor tolerability of the procedure; narrow nasal passages; significant curvature of the nasal septum etc).