In a first stage, the investigators will analyze in a prospective way a training cohort of HPTest datas from 74 subjects, involving 37 subjects with complaints and a Nijmegen questionnaire score of ≥23/64 (HVS+) matched on gender, age, height, weight and BMI category with 37 healthy controls without complaints and a Nijmegen questionnaire score of <23/64 (HVS-)(16).~All data will have to be collected by the same equipment and by the same operators in the pulmonology department of the CHU-St Pierre-Brussels between June 2018 and October 2021.~To rule out confounding respiratory pathology, each participant will have completed spirometry and methacholine testing, that will have a result within expected normal values.~For both cohorts, kinetics of the PETCO2 recorded during each of the 3 phases of the HPTest (adaptation, hyperventilation and recovery) will be mathematically modeled by an curvilinear model with the parameters (A, A', a and a') noted from the kinetic equation (TAU) : TAU [PETCO2(t)〖=A+a(1-exp〗^((b-t)/c))]. For any observed differences in parameters between groups, the Area Under Curves will be estimated at the cut-off that offers the best Sensitivity and Specificity. False negative and false positive rates will be estimated.~The probability of a type I error is set at 5%.~In a second stage, in order to confirm/infirm the results, a retrospective validation cohort from another care setting, including subjects without confounding pathology, who completed a Nijmegen questionnaire and a HVTest between 2018 and 2021, will be analysed in the same way than the training cohort.
The Hyperventilation Provocation Test (HPTest) associated with end-tidal CO2 pressure (PETCO2) measurement is a diagnostic tool for idiopathic hyperventilation syndrome (HVS). However, interpretation of HPTest remains unclear regarding the relevant PETCO2 values to consider and the occurrence of subjective symptoms.~This case-control study aims to identify accurate HPTest measurements for the diagnosis of HVS, regardless of symptoms occurrence.