Clinical trial NCT05189158: Ventilatory Responses to Hypercapnic and Hypoxic Conditions in Hyperventilants
Official title: Ventilatory Responses to Hypercapnic and Hypoxic Conditions in Hyperventilants
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Hyperventilation Syndrome
Hypercapnia
Hypoxia
Lead sponsor: Centre Hospitalier Universitaire Saint Pierre
Sponsor class: OTHER
Collaborators: name: Université Libre de Bruxelles
First posted: 2022-01-12
Enrollment: 24
Sex: ALL
Minimum age (years): 18
Maximum age (years): 99
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: NON_RANDOMIZED
Intervention model: PARALLEL
Primary purpose: DIAGNOSTIC

Brief summary: For almost a century, many hypotheses have converged on the idea of altered chemosensitivity in patients suffering from hyperventilation syndrome (HVS).

Given the evolution of current technical equipment and the ability to maximise true positives in HVS ( using the revised hyperventilation provocation test), it seems reasonable to investigate central and peripheral chemosensitivities in HVS subjects.

Detailed description: In the inter-war period, many medical investigators who studied the hyperventilation syndrome (HVS) had already questioned the chemosensitivity to CO2 in HVS patients, without being able to explore it for all intents and purposes.

It was subsequently observed that although HVS is not systematically linked to manifest resting hypocapnia, it is nevertheless systematically correlated with significant variability and complexity of ventilation.

This is consistent with the observations of an increased plant gain in HVS, to be related to an increased loop gain (due to instability of controller gain feedback).

On the other hand, some authors already noted that, when capnia is chronically compromised in HVS, it can be greatly altered by small, transient and barely perceptible increases in VE: a 10% increase in VE could indeed halve PetCO2, while a sigh would be able to decrease PetCO2 by up to 15mmHg.

More recently, teh assumption was made that peripheral chemosensitivity may be impaired in HVS patients.

For all these considerations, it seems reasonable to investigate central and peripheral chemosensitivities in identified HVS subjects on the basis of an objective test, such as the induced hyperventilation test.

Eligibility criteria: Inclusion Criteria:

* A plethysmography within subject's predicted values
* A negative metacholine test (no documented allergy)
* A hyperventilation provocation test result that is consistent with the Nijmegen questionnaire score, confirming either group classification (HVS+ or HVS-)

Exclusion Criteria:

* Each of the following known or documented conditions: chronic bronchitis (COPD), emphysema, asthma, cardiac disorder, neurological disorder, gastrointestinal disorder, thyroid disorder or psychological/psychiatric disorder
* Suspicious cardio-pulmonary exercise testing (CPET) with cardiac or respiratory limitation
* Pregnant women or women in the process of becoming pregnant
* Persons with a diving practice (amateur or professional),
* High-level athletes,
* Active smokers and
* persons using morphine, and/or barbiturates, and/or anxiolytics and/or sleeping pills

Primary outcomes:
measure: The slope of the ventilatory response to hypercapnia (HCVR)
timeFrame: baseline - during the test
measure: The slope of the ventilatory response to hypoxia (HOVR)
timeFrame: baseline - during the test
measure: Ventilatory recruitment threshold (VRT) of the HCVR
timeFrame: baseline - during the test
measure: Ventilatory recruitment threshold (VRT) of the HOVR
timeFrame: baseline - during the test
Secondary outcomes:
measure: Extrapolated apnoeic threshold of the HCVR
timeFrame: baseline - during the test
measure: Dyspnea
timeFrame: baseline, end of the test
Other outcomes:
Locations:
city: Bruxelles
country: Belgium
facility: CHU St Pierre
state: Brabant
Study officials:
References: