Prevalence of Nocturnal Hypoventilation in Obese Subjects Fiited With Continuous Positive Airway Pressure for Obstructive Sleep Apnea / Hypopnea Syndrome

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.

Overview

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.

Interventions

• Other Transcutaneous Oxy-Capnography
  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.
• Other Quality of life questionnaires
  Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, and the "Patient-Reported Hypoventilation Questionnaire".
• Other Arterial gasometry
  Arterial blood gas analysis will be performed only in patients presenting nocturnal hypoventilation.
• Other Body plethysmography
  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.
• Other Spirometry with reversibility test
  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.
• Other Clinical examination
  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.

Primary outcome measures

• Prevalence of nocturnal alveolar hypoventilation [Time frame: 1 month]

Eligibility criteria

Inclusion criteria

• 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

Exclusion criteria

• Patient under legal protection measure
• Non-compliant patients
• Pregnant or breast-feeding women (assessed on questioning)

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

N/A

Model

Single group

Masking

Open label

Primary purpose

Diagnostic

Study locations

France · 1 center

• CHU de Toulouse Hôpital Larrey — Toulouse

Identifiers

NCT: NCT07152990 · RC31/24/0290 · 2025-A00694-45

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗