Nocturnal HypoventilationCAPNOSOHNCT07152990
Prevalence of Nocturnal Hypoventilation in Obese Subjects Fiited With Continuous Positive Airway Pressure for Obstructive Sleep Apnea / Hypopnea Syndrome
A study testing Transcutaneous Oxy-Capnography, Quality of life questionnaires and Arterial gasometry in people with Nocturnal Hypoventilation and Obesity, run by University Hospital, Toulouse at 1 site in France.
Trial summary
CAPNOSOH study is a single-center study conducted at Toulouse University Hospital, aiming to estimate the prevalence of obese and apneic subjects maintaining nocturnal hypoventilation under continuous positive airway pressure (CPAP). Read more about this study
- Who is it for?
- Ages 18 to 80 years
- Conditions the study is for
- Nocturnal Hypoventilation, Obesity, Sleep Apnea Hypopnea Syndrome
- What is being tested?
- Transcutaneous Oxy-Capnography, Quality of life questionnaires and Arterial gasometry
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 139 participants
- Where
- 1 siteFrance
- Study dates
- Sep 2025to May 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 80 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Obese patients (Body Mass Index > 30 kg/m2)
- Fitted by one of the following providers: ASTEN, Vitalaire, Orkyn, ISIS, RespiO2, BASTIDE for > 3 months with compliance of more than 4 consecutive hours per night in average during 3 months
- "Good quality" criteria for continuous positive airway pressure (CPAP) treatment: compliance > 4 consecutive hours per night, unintentional leaks < limit defined by the manufacturer, residual AHI < 10/h
- Aged 18 to 80
- Affiliated or beneficiaries of the social security system or equivalent
- Having given written informed consent
- Able to understand instructions and information given
Who cannot join
- Patient under legal protection measure
- Non-compliant patients
- Pregnant or breast-feeding women (assessed on questioning)
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
France1 site
CHU de Toulouse Hôpital Larrey
Toulouse, Occitanie, 31059
Sandrine PONTIER, 05 67 77 18 46, pontier.s@chu-toulouse.fr
Sandrine PONTIER
About this study
Official title: Prevalence of Nocturnal Hypoventilation Diagnosed by Transcutaneous Oxy-capnography in a Population of Obese Subjects Fitted With Continuous Positive Airway Pressure for Obstructive Sleep Apnea Hypopnea Syndrome.
CAPNOSOH study is a single-center study conducted at Toulouse University Hospital, aiming to estimate the prevalence of obese and apneic subjects maintaining nocturnal hypoventilation under continuous positive airway pressure (CPAP).
Read the detailed description
Obstructive sleep apnea hypopnea syndrome (OSAS) is highly prevalent in the global population (1 in 10 people worldwide according to Inserm), particularly in relation to the increase in the prevalence of obesity. The standard treatment for this pathology is continuous positive airway pressure (CPAP) which most often allows, when properly applied and adjusted, the normalization of symptoms and the apnea-hypopnea index (AHI). In addition to OSAHS, some obese subjects are at risk of presenting hypoventilation obesity syndrome (OHS) defined by the presence of obesity (body mass index [BMI] > 30 kg/m2) associated with diurnal hypoventilation. (PaCO2 > 45 mmHg) in the absence of other respiratory pathology. Identifying patients with OS is often difficult but essential, as early as possible.
Transcutaneous capnography, when properly performed and interpreted, is a much more informative tool than nocturnal oximetry, and could therefore allow better screening for these patients. It is an examination increasingly used in pulmonology departments/sleep centers.
The CAPNOSOH study is a single-center study conducted at Toulouse University Hospital, aiming to estimate the prevalence of obese and apneic subjects maintaining nocturnal hypoventilation under continuous positive airway pressure (CPAP). The study hypothesis is based on the limited data present in the literature. This is preliminary work for a multicenter study aimed at determining the impact of nocturnal hypoventilation without daytime hypercapnia on the quality of life and morbidity and mortality of patients.
We estimate that between 10 to 20% of obese subjects on CPAP hypoventilate at night.
- Being tested
- Transcutaneous Oxy-Capnography, Quality of life questionnaires, Arterial gasometry, Body plethysmography, Spirometry with reversibility test
- Keywords
- Nocturnal hypoventilation, obesity, sleep apnea syndrome, continuous positive pressure, transcutaneous capnography
- Medical subject headings
- Obesity, Sleep Apnea, Obstructive, Sleep Apnea Syndromes
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Transcutaneous Oxy-CapnographyOther
Patients will be monitored using transcutaneous oxy-capnography to evaluate the prevalence of nocturnal alveolar hypoventilation in these population. Nocturnal alveolar hypoventilation is defined with PTcCO2 > 49 mmHg more than 10% of the time of capnographic recording.
Quality of life questionnairesOther
Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, and the "Patient-Reported Hypoventilation Questionnaire".
Arterial gasometryOther
Arterial blood gas analysis will be performed only in patients presenting nocturnal hypoventilation.
Body plethysmographyOther
Plethysmography will be performed only in patients presenting nocturnal hypoventilation. It will be used to measure lung volume and assess pulmonary function. This non-invasive procedure involves the patient breathing into a device that measures changes in pressure within a sealed chamber.
Spirometry with reversibility testOther
The intervention will be performed only in patients presenting nocturnal hypoventilation. Spirometry with a reversibility test will be performed to assess lung function and evaluate the response to bronchodilators. The procedure involves measuring forced expiratory volume and forced vital capacity before and after the administration of a bronchodilator.
Clinical examinationOther
Clinical exam will be performed only in patients presenting nocturnal hypoventilation. It will consists of standard interview/clinical examination: vital signs, cardiological, pulmonary, abdominal, neurological examination, search for clinical signs of nocturnal hypoventilation, search for signs of hypoxia/hypercapnia, pulmonary auscultation.
| Study group | Role | What they receive |
|---|---|---|
| Obese Patients with Obstructive Sleep Apnea/Hypopnea | Other | Not described Receives: Other: Transcutaneous Oxy-Capnography; Other: Quality of life questionnaires; Other: Arterial gasometry; Other: Body plethysmography; Other: Spirometry with reversibility test; Other: Clinical examination |
What is being measured
The primary outcome is the main question the study is designed to answer.
Prevalence of nocturnal alveolar hypoventilation
Prevalence of nocturnal alveolar hypoventilation will be diagnosed by transcutaneous oxy-capnography. Nocturnal alveolar hypoventilation is defined with PTcCO2 > 49 mmHg more than 10% of the time of capnographic recording.
Measured: 1 month
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Sep 2025
- Study startSep 2025 (estimated)
- Primary completionMay 2027 (estimated)
- Study completionMay 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Nocturnal HypoventilationStudies of the same condition, open and under way.
- More trials run by University Hospital, ToulouseThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Diagnosis
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- All patients will undergo transcutaneous oxy-capnography and answer quality of life questionnaires. Only patients presenting nocturnal hypoventilation defined with PTcCO2 \> 49 mmHg more than 10% of the time of capnographic recording will continue the study with additional interventions. Patients without nocturnal hypoventilation will finish the study after the capnographic recording visit.
- Masking
- None (open label)
- Enrolment
- 139 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University Hospital, Toulouse
- Sponsor type
- University, hospital or other
- Collaborators
- Fonds de dotation Agir pour les Maladies Chroniques
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07152990
- Sponsor's protocol ID
- RC31/24/0290
- Other IDs
- 2025-A00694-45
- Acronym
- CAPNOSOH
- Status last verified
- Aug 2025
- First submitted
- 25 Aug 2025
- Last updated
- 3 Sep 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 3 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Prevalence of Nocturnal Hypoventilation Diagnosed by Transcutaneous Oxy-capnography in a Population of Obese Subjects Fitted With Continuous Positive Airway Pressure for Obstructive Sleep Apnea Hypopnea Syndrome.
- ClinicalTrials.gov ID
- NCT07152990
- Acronym / sponsor ID
- CAPNOSOH / RC31/24/0290
- Keywords
- Nocturnal hypoventilation, obesity, sleep apnea syndrome, continuous positive pressure, transcutaneous capnography
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 139 participants (estimated)
- Lead sponsor
- University Hospital, ToulouseUniversity, hospital or other
- Collaborators
- Fonds de dotation Agir pour les Maladies Chroniques
- Study start
- Sep 2025 (estimated)
- Primary completion
- May 2027 (estimated)
- Study completion
- May 2027 (estimated)
- First posted
- 3 Sep 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
CAPNOSOH study is a single-center study conducted at Toulouse University Hospital, aiming to estimate the prevalence of obese and apneic subjects maintaining nocturnal hypoventilation under continuous positive airway pressure (CPAP).
Detailed description
Obstructive sleep apnea hypopnea syndrome (OSAS) is highly prevalent in the global population (1 in 10 people worldwide according to Inserm), particularly in relation to the increase in the prevalence of obesity. The standard treatment for this pathology is continuous positive airway pressure (CPAP) which most often allows, when properly applied and adjusted, the normalization of symptoms and the apnea-hypopnea index (AHI). In addition to OSAHS, some obese subjects are at risk of presenting hypoventilation obesity syndrome (OHS) defined by the presence of obesity (body mass index [BMI] > 30 kg/m2) associated with diurnal hypoventilation. (PaCO2 > 45 mmHg) in the absence of other respiratory pathology. Identifying patients with OS is often difficult but essential, as early as possible.
Transcutaneous capnography, when properly performed and interpreted, is a much more informative tool than nocturnal oximetry, and could therefore allow better screening for these patients. It is an examination increasingly used in pulmonology departments/sleep centers.
The CAPNOSOH study is a single-center study conducted at Toulouse University Hospital, aiming to estimate the prevalence of obese and apneic subjects maintaining nocturnal hypoventilation under continuous positive airway pressure (CPAP). The study hypothesis is based on the limited data present in the literature. This is preliminary work for a multicenter study aimed at determining the impact of nocturnal hypoventilation without daytime hypercapnia on the quality of life and morbidity and mortality of patients.
We estimate that between 10 to 20% of obese subjects on CPAP hypoventilate at night.
Study design
- Primary purpose
- Diagnosis
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- All patients will undergo transcutaneous oxy-capnography and answer quality of life questionnaires. Only patients presenting nocturnal hypoventilation defined with PTcCO2 > 49 mmHg more than 10% of the time of capnographic recording will continue the study with additional interventions. Patients without nocturnal hypoventilation will finish the study after the capnographic recording visit.
| Arm | Type | Receives |
|---|---|---|
| Obese Patients with Obstructive Sleep Apnea/Hypopnea | Other | Other: Transcutaneous Oxy-Capnography, Other: Quality of life questionnaires, Other: Arterial gasometry, Other: Body plethysmography, Other: Spirometry with reversibility test, Other: Clinical examination |
Who may qualify
- Ages
- 18 to 80 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (7 listed)
- Obese patients (Body Mass Index > 30 kg/m2)
- Fitted by one of the following providers: ASTEN, Vitalaire, Orkyn, ISIS, RespiO2, BASTIDE for > 3 months with compliance of more than 4 consecutive hours per night in average during 3 months
- "Good quality" criteria for continuous positive airway pressure (CPAP) treatment: compliance > 4 consecutive hours per night, unintentional leaks < limit defined by the manufacturer, residual AHI < 10/h
- Aged 18 to 80
- Affiliated or beneficiaries of the social security system or equivalent
Key exclusion criteria (3 listed)
- Patient under legal protection measure
- Non-compliant patients
- Pregnant or breast-feeding women (assessed on questioning)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Transcutaneous Oxy-CapnographyPatients will be monitored using transcutaneous oxy-capnography to evaluate the prevalence of nocturnal alveolar hypoventilation in these population. Nocturnal alveolar hypoventilation is defined with PTcCO2 > 49 mmHg more than 10% of the time of capnographic recording. | Other | Obese Patients with Obstructive Sleep Apnea/Hypopnea |
| Quality of life questionnairesEpworth Sleepiness Scale, Pittsburgh Sleep Quality Index, and the "Patient-Reported Hypoventilation Questionnaire". | Other | Obese Patients with Obstructive Sleep Apnea/Hypopnea |
| Arterial gasometryArterial blood gas analysis will be performed only in patients presenting nocturnal hypoventilation. | Other | Obese Patients with Obstructive Sleep Apnea/Hypopnea |
| Body plethysmographyPlethysmography will be performed only in patients presenting nocturnal hypoventilation. It will be used to measure lung volume and assess pulmonary function. This non-invasive procedure involves the patient breathing into a device that measures changes in pressure within a sealed chamber. | Other | Obese Patients with Obstructive Sleep Apnea/Hypopnea |
| Spirometry with reversibility testThe intervention will be performed only in patients presenting nocturnal hypoventilation. Spirometry with a reversibility test will be performed to assess lung function and evaluate the response to bronchodilators. The procedure involves measuring forced expiratory volume and forced vital capacity before and after the administration of a bronchodilator. | Other | Obese Patients with Obstructive Sleep Apnea/Hypopnea |
| Clinical examinationClinical exam will be performed only in patients presenting nocturnal hypoventilation. It will consists of standard interview/clinical examination: vital signs, cardiological, pulmonary, abdominal, neurological examination, search for clinical signs of nocturnal hypoventilation, search for signs of hypoxia/hypercapnia, pulmonary auscultation. | Other | Obese Patients with Obstructive Sleep Apnea/Hypopnea |
Primary outcome
Prevalence of nocturnal alveolar hypoventilation
Time frame: 1 month
Prevalence of nocturnal alveolar hypoventilation will be diagnosed by transcutaneous oxy-capnography. Nocturnal alveolar hypoventilation is defined with PTcCO2 > 49 mmHg more than 10% of the time of capnographic recording.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Sep 2025.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Transcutaneous Oxy-Capnography, Quality of life questionnaires and Arterial gasometry in people with Nocturnal Hypoventilation and Obesity, run by University Hospital, Toulouse at 1 site in France.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 3 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in France. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Sandrine PONTIER (05 67 77 18 46, pontier.s@chu-toulouse.fr), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Prevalence of nocturnal alveolar hypoventilation (time frame: 1 month). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Sep 2025.