Methods
The study was done from December 2017 to December 2020 and included children aged 8-19 with a diagnosis of pectus excavatum. The project protocol was approved by the Ethics Committee of the Jessenius Faculty of Medicine in Martin. All patients and their legal representatives were informed of the nature and purpose of the examination and had signed informed consent. The work was carried out at the Centre for the Diagnosis of Functional Disorders in Childhood at the Clinic for Children and Adolescents, JLF UK and UNM in Martin. The study included pediatric patients and adolescents with PE who were referred from the Pediatric Surgery Clinic and were candidates for conservative therapy (with vacuum bell) or the surgical treatment. Only patients who were without vacuum bell treatment at the time of testing and did not undergo corrective surgery were included in the cohort of the patients. Chest CT study with the determination of the Haller index was not required.
After basic examinations (12-lead ECG, spirometry), CPET on treadmill (RAM Clinical 870A, Belgium) was performed using the breath-by-breath analysis of exspired gas (Geratherm Respiratory, Germany). An individualized load protocol was used to achieve the maximum tolerated load between 8 and 12 minutes. Prior to the exercise, a manoeuvre was performed to determine the inspiratory capacity during calm breathing, and subsequently the inspiratory capacity was paired with the tidal volume. The patient was monitored during exercise with a continuously recorded 12-lead ECG. During exercise, respiratory parameters (tidal volum - Vt, minute ventilation - VE, breathing reserve - BR, breathing rate - BF, end-tidal CO2 - PETCO2, end-tidal O2PETO2), oxygen consumption parameters (O2Pulse, VO2), cardiovascular parameters (ECG, heart rate - HR), respiratory exchange ratio (RER) were recorded and then ventilation efficiency parameters (VE/VO2, VE/VCO2) and oxygen extraction efficiencies (VO2/WR, oxygen uptake efficacy slope - OUES) were calculated. All examinations were performed in the morning and the patients were instructed on the need for at least 24 hours of rest and sufficient hydration before the examination.
Analysis of the obtained data was performed in Systat 13 (Systat Software Inc.). Student’s T-test was used to compare the equality of population averages (for parametric data). Pearson’s test was used to express the correlation of the monitored parameters. When plotting the dependent variables, we used direct linear regression of the obtained data to linearly predict future values. The prediction was expressed as x + 30% (where x is the maximum of the values ​​obtained).