Obstructive Sleep ApneaSlim-OSANCT04793334
Underlying Mechanisms of Obesity-induced Obstructive Sleep Apnea
An observational study of Obstructive Sleep Apnea and Obesity, run by Brandon Nokes at 1 site in United States.
Trial summary
Obesity is a common risk factor for the development of obstructive sleep apnea. However, not all subjects with obesity develop obstructive sleep apnea. This study will attempt to determine the mechanistic drivers between obesity and obstructive sleep apnea. Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Obstructive Sleep Apnea, Obesity
- What is being tested?
- sleeve gastectomy
- Type of treatment
- Surgery or procedure
- How many people
- 106 participants
- Where
- 1 siteUnited States
- Study dates
- 20 Mar 2021to 31 May 2025
- Phase
- Observational
- Are there results?
- None posted in the registry
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 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Noting the inclusion and exclusion criteria above, we aim to recruit 110 patients, anticipating 20% drop out and a final n of 90. Further, we aim for to recruit 60 participants with OSA and 30 participants without OSA.
Who may be able to join
- - Men and women
- Ages >= 18-65 years old
- BMI 35 kg/m2--and above
- Scheduled for sleeve gastrectomy (bariatric surgery)
Who cannot join
- Any cardiovascular, pulmonary or renal disease other than well-controlled hypertension or asthma.
- Pregnancy
- Currently smoking
- Any respiratory disorder other than OSA or well controlled asthma
- contraindication to MRI
Trial locations and contacts
1 site in 1 country.
United States1 site
UCSD - Altman Clinical Research Institute (ACTRI)
La Jolla, California, 92037
About this study
Obesity is a common risk factor for the development of obstructive sleep apnea. However, not all subjects with obesity develop obstructive sleep apnea. This study will attempt to determine the mechanistic drivers between obesity and obstructive sleep apnea.
Read the detailed description
Obstructive sleep apnea (OSA) is a highly prevalent disease with major neurocognitive and cardiovascular sequelae. Obesity is a major risk factor for OSA, but the underlying mechanisms remain unclear. Given the rising prevalence of obesity and the lack of adequate therapies for some afflicted patients, further mechanistic work is clearly required. Bariatric surgery is being done increasingly with compelling outcome data emerging; however, clinical response to weight loss is highly variable. In some patients, OSA is not present at baseline, despite morbid obesity, in other patients, OSA resolves following bariatric surgery, while other patients have persistence of OSA despite weight loss, and still other patients can experience re-emergence of OSA in long term follow-up studies after bariatric surgery. OSA can occur due to several major pathophysiological factors including pharyngeal anatomy, pharyngeal dilator muscle dysfunction, unstable ventilatory control, end- expiratory lung volume and arousal threshold. As a result considerable complexity exists in the obesity/OSA relationship, suggesting the need for further research. First, the investigators will perform a baseline evaluation of pathophysiological traits among obese people prior to weight loss surgery. Because some people will have OSA and some will not, the investigators will define the potential mechanisms underlying OSA and potential protective mechanisms among obese people without OSA (pharyngeal critical closing pressure Pcrit primary outcome). Second, the investigators will re-evaluate these same individuals from the standpoint of sleep study and pathophysiological traits six months following bariatric surgery after a variable degree of weight loss. The investigators anticipate that some OSA patients will have resolution of OSA whereas others will have persistence of disease. For non-OSA patients undergoing weight loss, the investigators will have a positive control group which will allow the investigators to account for non-specific effects of weight loss. This aim will allow the investigators to test the hypothesis that pharyngeal mechanics is the predominant mechanism whereby weight loss leads to improvement in OSA. Third, the investigators will perform magnetic resonance imaging during wakefulness at functional residual capacity, total lung capacity and residual volume on participants at baseline and 6months following bariatric surgery. This aim will allow the investigators to perform structure/function assessments in our participants, to define the impact of weight loss on pharyngeal anatomy, and to quantify the lung volume dependence of the upper airway before and after weight loss. The acquired data will also be used for computational modeling including dynamic assessment of pharyngeal function during tidal breathing. As a result of the proposed research, the investigators are confident that the investigators will gain major insights into the as yet unanswered question "why does obesity (sometimes) cause sleep apnea". This research will have major therapeutic implications as it will allow the investigators to individualize therapy for afflicted patients.
- Conditions
- Obstructive Sleep Apnea, Obesity
- Being tested
- sleeve gastectomy
- Medical subject headings
- Sleep Apnea, Obstructive, Obesity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
sleeve gastectomyProcedure or surgery
routine sleeve gastrectomy
| Study group | Role | What they receive |
|---|---|---|
| Obese + OSA | Inclusion Criteria:
* Men and women
* Ages >= 18-65 years old
* BMI 35 kg/m2-above
* Scheduled for sleeve gastrectomy (bariatric surgery)
* OSA identified by PSG
Exclusion Criteria:
* Any cardiovascular, pulmonary or renal disease other than well-controlled hypertension or asthma.
* Pregnancy
* Currently smoking
* Any respiratory disorder other than OSA or well controlled asthma
* contraindication to MRI Receives: Procedure: sleeve gastectomy | |
| Obese without OSA | Inclusion Criteria:
* Men and women
* Ages >= 18-65 years old
* BMI 35kg/m2 and above
* Scheduled for sleeve gastrectomy (bariatric surgery)
* No OSA identified by PSG
Exclusion Criteria:
* Any cardiovascular, pulmonary or renal disease other than well-controlled hypertension or asthma.
* Pregnancy
* Currently smoking
* Any respiratory disorder other than OSA or well controlled asthma
* contraindication to MRI Receives: Procedure: sleeve gastectomy |
What is being measured
The primary outcome is the main question the study is designed to answer.
muscle traits contributing to OSA in obesity - change is being assessed over time
- To measure upper airway collapsibility as well as the other traits (e.g. muscle responsiveness) in both groups. The traits can be measured during sleep using our well-validated research method that mimics transient upper airway obstruction and importantly, assesses the individual's response to hypoventilation
Measured: Time point 1: Within 1 month of bariatric surgery, Time point 2: 6 months following bariatric surgery
changes in pcrit after bariatric surgery
- We will reassess obese people with and without OSA following major weight loss (bariatric surgery). This aim will allow us to test the hypothesis that patients who experience improvement in OSA will be those with the greatest improvement in upper airway mechanics (Pcrit). The obese people without OSA undergoing weight loss will be a positive control group, which will allow us to exclude non-specific effects of weight loss.
Measured: Time point 1: Within 1 month of bariatric surgery, Time point 2: 6 months following bariatric surgery
MRI upper airway changes following bariatric surgery - change is being assessed over time
- To determine the anatomic correlates of upper airway collapsibility in both groups using magnetic resonance imaging during natural sleep.
Measured: Time point 1: Within 1 month of bariatric surgery, Time point 2: 6 months following bariatric surgery
Secondary outcomes (1)
exploratory outcomes
phlebotomy for ABG and transcriptomic assessments - change is being assessed over time
Measured: Time point 1: Within 1 month of bariatric surgery, Time point 2: 6 months following bariatric surgery
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted11 Mar 2021
- Study start20 Mar 2021
- Primary completion31 May 2025
- Study completion31 May 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Obstructive Sleep ApneaStudies of the same condition, open and under way.
- 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
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 106 participants (actual)
Sponsor and investigators
- Lead sponsor
- Brandon Nokes
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor-investigator, Brandon Nokes, University of California, San Diego
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04793334
- Sponsor's protocol ID
- UCSD HRPP 191948
- Acronym
- Slim-OSA
- Status last verified
- Feb 2026
- First submitted
- 5 Mar 2021
- Last updated
- 27 Feb 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 27 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Underlying Mechanisms of Obesity-induced Obstructive Sleep Apnea
- ClinicalTrials.gov ID
- NCT04793334
- Acronym / sponsor ID
- Slim-OSA / UCSD HRPP 191948
- Conditions
- Obstructive Sleep Apnea, Obesity
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 106 participants (actual)
- Lead sponsor
- Brandon NokesUniversity, hospital or other
- Study start
- 20 Mar 2021 (actual)
- Primary completion
- 31 May 2025 (actual)
- Study completion
- 31 May 2025 (actual)
- First posted
- 11 Mar 2021 (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.
Obesity is a common risk factor for the development of obstructive sleep apnea. However, not all subjects with obesity develop obstructive sleep apnea. This study will attempt to determine the mechanistic drivers between obesity and obstructive sleep apnea.
Detailed description
Obstructive sleep apnea (OSA) is a highly prevalent disease with major neurocognitive and cardiovascular sequelae. Obesity is a major risk factor for OSA, but the underlying mechanisms remain unclear. Given the rising prevalence of obesity and the lack of adequate therapies for some afflicted patients, further mechanistic work is clearly required. Bariatric surgery is being done increasingly with compelling outcome data emerging; however, clinical response to weight loss is highly variable. In some patients, OSA is not present at baseline, despite morbid obesity, in other patients, OSA resolves following bariatric surgery, while other patients have persistence of OSA despite weight loss, and still other patients can experience re-emergence of OSA in long term follow-up studies after bariatric surgery. OSA can occur due to several major pathophysiological factors including pharyngeal anatomy, pharyngeal dilator muscle dysfunction, unstable ventilatory control, end- expiratory lung volume and arousal threshold. As a result considerable complexity exists in the obesity/OSA relationship, suggesting the need for further research. First, the investigators will perform a baseline evaluation of pathophysiological traits among obese people prior to weight loss surgery. Because some people will have OSA and some will not, the investigators will define the potential mechanisms underlying OSA and potential protective mechanisms among obese people without OSA (pharyngeal critical closing pressure Pcrit primary outcome). Second, the investigators will re-evaluate these same individuals from the standpoint of sleep study and pathophysiological traits six months following bariatric surgery after a variable degree of weight loss. The investigators anticipate that some OSA patients will have resolution of OSA whereas others will have persistence of disease. For non-OSA patients undergoing weight loss, the investigators will have a positive control group which will allow the investigators to account for non-specific effects of weight loss. This aim will allow the investigators to test the hypothesis that pharyngeal mechanics is the predominant mechanism whereby weight loss leads to improvement in OSA. Third, the investigators will perform magnetic resonance imaging during wakefulness at functional residual capacity, total lung capacity and residual volume on participants at baseline and 6months following bariatric surgery. This aim will allow the investigators to perform structure/function assessments in our participants, to define the impact of weight loss on pharyngeal anatomy, and to quantify the lung volume dependence of the upper airway before and after weight loss. The acquired data will also be used for computational modeling including dynamic assessment of pharyngeal function during tidal breathing. As a result of the proposed research, the investigators are confident that the investigators will gain major insights into the as yet unanswered question "why does obesity (sometimes) cause sleep apnea". This research will have major therapeutic implications as it will allow the investigators to individualize therapy for afflicted patients.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Obese + OSA | – | Procedure: sleeve gastectomyInclusion Criteria: * Men and women * Ages >= 18-65 years old * BMI 35 kg/m2-above * Scheduled for sleeve gastrectomy (bariatric surgery) * OSA identified by PSG Exclusion Criteria: * Any cardiovascular, pulmonary or renal disease other than well-controlled hypertension or asthma. * Pregnancy * Currently smoking * Any respiratory disorder other than OSA or well controlled asthma * contraindication to MRI |
| Obese without OSA | – | Procedure: sleeve gastectomyInclusion Criteria: * Men and women * Ages >= 18-65 years old * BMI 35kg/m2 and above * Scheduled for sleeve gastrectomy (bariatric surgery) * No OSA identified by PSG Exclusion Criteria: * Any cardiovascular, pulmonary or renal disease other than well-controlled hypertension or asthma. * Pregnancy * Currently smoking * Any respiratory disorder other than OSA or well controlled asthma * contraindication to MRI |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Noting the inclusion and exclusion criteria above, we aim to recruit 110 patients, anticipating 20% drop out and a final n of 90. Further, we aim for to recruit 60 participants with OSA and 30 participants without OSA.
Key inclusion criteria (4 listed)
- - Men and women
- Ages >= 18-65 years old
- BMI 35 kg/m2--and above
- Scheduled for sleeve gastrectomy (bariatric surgery)
Key exclusion criteria (5 listed)
- Any cardiovascular, pulmonary or renal disease other than well-controlled hypertension or asthma.
- Pregnancy
- Currently smoking
- Any respiratory disorder other than OSA or well controlled asthma
- contraindication to MRI
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 |
|---|---|---|
| sleeve gastectomyroutine sleeve gastrectomy | Procedure or surgery | Obese + OSA, Obese without OSA |
Primary outcome
muscle traits contributing to OSA in obesity - change is being assessed over time
Time frame: Time point 1: Within 1 month of bariatric surgery, Time point 2: 6 months following bariatric surgery
1. To measure upper airway collapsibility as well as the other traits (e.g. muscle responsiveness) in both groups. The traits can be measured during sleep using our well-validated research method that mimics transient upper airway obstruction and importantly, assesses the individual's response to hypoventilation
changes in pcrit after bariatric surgery
Time frame: Time point 1: Within 1 month of bariatric surgery, Time point 2: 6 months following bariatric surgery
2. We will reassess obese people with and without OSA following major weight loss (bariatric surgery). This aim will allow us to test the hypothesis that patients who experience improvement in OSA will be those with the greatest improvement in upper airway mechanics (Pcrit). The obese people without OSA undergoing weight loss will be a positive control group, which will allow us to exclude non-specific effects of weight loss.
MRI upper airway changes following bariatric surgery - change is being assessed over time
Time frame: Time point 1: Within 1 month of bariatric surgery, Time point 2: 6 months following bariatric surgery
3. To determine the anatomic correlates of upper airway collapsibility in both groups using magnetic resonance imaging during natural sleep.
1 secondary outcome
exploratory outcomes
Time frame: Time point 1: Within 1 month of bariatric surgery, Time point 2: 6 months following bariatric surgery
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 27 Feb 2026.
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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. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Obstructive Sleep Apnea and Obesity, run by Brandon Nokes at 1 site in United States.
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 4 inclusion and 5 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: finished, as of the sponsor's last update on 27 Feb 2026. 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 United States. 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
muscle traits contributing to OSA in obesity - change is being assessed over time (time frame: Time point 1: Within 1 month of bariatric surgery, Time point 2: 6 months following bariatric surgery). The study lists 3 primary outcomes in all. 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 27 Feb 2026.