Hyper Ventilation Syndrome is a frequent disease affecting adults whose diagnosis is often belated or even unrecognized due to the lack of "gold standard" criteria. Its diagnosis currently relies on the Nijmegen score associated with a PetCO2 assesment using a hyperventilation provocation test. Correlation between Nijmegen Questionnaire scores and PetCO2 appears highly variable. PtcCO2 monitoring is a noninvasive alternative method providing a continuous estimation of arterial CO2 pressure (PaCO2) which could represent an advantageous alternative to PetCO2 measurements. Several reports have demonstrated that PtcCO2 monitoring reflects more faithfully PaCO2 than PetCO2, no study have evaluated its value in this indication.

The primary aim of the study is to compare the diagnostic value of PtcPCO2 monitoring with PetCO2, the method currently used.

Included patient will be invited to fill in the Nijmegen questionnaire and an ambient air gas measurement will be performed. PtcCO2 (mmHg) will be simultaneously measured during hyperventilation test. Nijmegen score signs reproduced by the test will be analysed. HVS diagnosis will be assessed by usual criteria (PetCO2 <30 mmHg at the end of hyperventilation test or under the PetCO2 value at rest, Nijmegen score> 23).

PtcCO2 data will be blinded interpreted later. We will compare if PetCO2 and PtcCO2 leads to the same diagnosis or not.

Primary Goal:

Show that the use of either of the two pCO2 measurements leads to the same diagnostic conclusion in HVS diagnosis with a likelihood greater than 80 %.

Secondary Outcome Measures :

Evaluate the correlation between PtcCO2 and PtcCO2 measurements Evaluate tolerance to the hyperventilation test

Inclusion Criteria :

1. The patient must have reached the age of the civil majority (≥ 18 yo)
2. All patients refered to the Physiology department of Rouen University Hospital, France, for an hyperventilation test
3. The patient must be a member or beneficiary of a health insurance program
4. The patient must have given his / her free and informed consent and signed the consent

Exclusion Criteria :

1. Sepsis
2. Hypercapnia (PaCO2 > 50mmHg)
3. Patient treated by long-term oxygen therapy
4. Subjects under judicial protection, or adults under any kind of guardianship or under judicial control
5. Pregnancy or breastfeeding women
6. Electrolytic unbalance
7. Hyperthyroidism
8. Neurological disease
9. Probability of drug-induced hyperventilation (progestagens , aspirin, beta agonists)

Inclusion Criteria:

1. The patient must have reached the age of the civil majority (≥ 18 yo)
2. All patients refered to the Physiology department of Rouen University Hospital, France, for an hyperventilation test
3. The patient must be a member or beneficiary of a health insurance program
4. The patient must have given his / her free and informed consent and signed the consent

Exclusion Criteria:

1. Sepsis
2. Hypercapnia (PaCO2 > 50mmHg)
3. Patient treated by long-term oxygen therapy
4. Subjects under judicial protection, or adults under any kind of guardianship or under judicial control
5. Pregnancy or breastfeeding women
6. Electrolytic unbalance
7. Hyperthyroidism
8. Neurological disease
9. Probability of drug-induced hyperventilation (progestagens , aspirin, beta agonists)