Predictive Properties of the Hyperventilation Provocation Test for the Diagnosis of the Hyperventilation Syndrome
Condition: Hyperventilation Syndrome
MeSH terms: Hyperventilation; Syndrome
Study type: Observational

Summary: 
      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: 
      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.
    

Intervention name(s): Hyperventilation Provocation Test (HPTest)
Intervention type(s): Diagnostic Test
Intervention description(s): 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.
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Patients who visited the pulmonary department and performed a HPTest on medical
        prescription