Predictive Properties of the Hyperventilation Provocation Test for the Diagnosis of the Hyperventilation Syndrome

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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Predictive Properties of the Hyperventilation Provocation Test for the Diagnosis of the Hyperventilation Syndrome

Conditions
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Hyperventilation Syndrome

Intervention / Treatment
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* Diagnostic Test: Hyperventilation Provocation Test (HPTest)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Anyone over 18 years of age who has completed an HPTest and a Nijmegen questionnaire between 2015 and 2020 Exclusion Criteria: -

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 99 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| HVS+<br>Subjects without documented respiratory or cardiac disease, with a spirometry and metacholine tests within expected values AND with complaints documented by a Nijmegen questionnaire score of ≥23/64 (suspected of idiopathic hyperventilation) | Diagnostic Test: Hyperventilation Provocation Test (HPTest)<br>* During the HPTest, the subject is comfortably seated in a chair with armrests and breathes in a mouthpiece with a salivary collector and a nasal clamp. Parameters of ventilation and gas exchange are analyzed via an Oxycon ProTM (SN808008) with TripleV-Volume Sensor digital(Jaeger). The HPTest begins with a 3-minutes adaptation phase during which the patient is asked to breathe normally. During the 3-minutes of voluntary hyperventilation phase, the patient is asked to increase his tidal volume and support a breath rate of at least 30/min in order to reduce his PETCO2 by at least 50%. During the recovery phase of the HPTest, the patient is invited to regain a natural breathing for 5 minutes, without guidance on tidal volume or breath rate.<br>|
| HVS-<br>Healthy controls without documented respiratory or cardiac disease, with a spirometry and metacholine tests within expected values AND without complaints documented by a Nijmegen questionnaire score of <23/64 | Diagnostic Test: Hyperventilation Provocation Test (HPTest)<br>* During the HPTest, the subject is comfortably seated in a chair with armrests and breathes in a mouthpiece with a salivary collector and a nasal clamp. Parameters of ventilation and gas exchange are analyzed via an Oxycon ProTM (SN808008) with TripleV-Volume Sensor digital(Jaeger). The HPTest begins with a 3-minutes adaptation phase during which the patient is asked to breathe normally. During the 3-minutes of voluntary hyperventilation phase, the patient is asked to increase his tidal volume and support a breath rate of at least 30/min in order to reduce his PETCO2 by at least 50%. During the recovery phase of the HPTest, the patient is invited to regain a natural breathing for 5 minutes, without guidance on tidal volume or breath rate.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| PetCO2 recovery (5min) | PetCO2 at the end (5th minute) of the recovery phase of the HPTest | 5 minute of recovery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| PetCO2 recovery (3min) | PetCO2 at the end (3d minute) of the recovery phase of the HPTest | 3 minute of recovery |