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).