Sleep-disordered BreathingPhase 2OPIO2NCT07923760
Supplemental Oxygen for Sleep-Disordered Breathing in Adults With Chronic Opioid Use.
A Phase 2 study testing Supplemental Oxygen in people with Sleep-disordered Breathing and Chronic Opioid Use, run by University of California, San Diego at 1 site in United States.
Trial summary
This study will evaluate whether supplemental oxygen given during sleep improves breathing stability and sleep-disordered breathing in adults who use prescription opioids long term. Participants will receive both supplemental oxygen and sham air during separate overnight sleep studies in a randomized order. Read more about this study
- Who is it for?
- Ages 18 to 75 years
- Conditions the study is for
- Sleep-disordered Breathing, Chronic Opioid Use
- What is being tested?
- Supplemental Oxygen
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 62 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Dec 2026to 1 Dec 2031
- Phase
- Phase 2
- 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 75 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Age 18 to 75 years.
- Chronic opioid use for ≥3 months with a daily opioid dose equivalent to at least 20 mg of oral morphine (morphine equivalent daily dose [MEqD]). Examples include approximately 13 mg oxycodone, 20 mg hydrocodone, 100 mg tramadol, or equivalent doses of other opioids.
- Ability and willingness to comply with study procedures, including overnight laboratory polysomnography and administration of oxygen or sham air in the laboratory.
- Ability to provide written informed consent.
- For participants able to become pregnant: agreement to use an effective contraceptive method (e.g., a licensed hormonal or intrauterine method, or an effective barrier method) during study participation. The study team will review and document the method before enrollment.
- Recruitment will target approximately equal numbers of males and females to enable consideration of sex as a biological variable, consistent with NIH policy.
- In addition to the enrollment criteria, participants must meet the following criterion to be eligible for randomization:
- Diagnosis of sleep-disordered breathing (SDB), defined as AASM-recommended apnea-hypopnea index (AHI3A) ≥5 events per hour on a qualifying sleep study. AHI3A includes hypopnea definition ≥30% airflow reduction lasting ≥10 seconds, accompanied by ≥3% SpO2 desaturation or arousal.
Who cannot join
- Body mass index (BMI) >35 kg/m².
- Requirement for supplemental oxygen therapy outside of the study.
- Current use of CPAP or other sleep-apnea treatment that cannot safely be withheld during OPIO2 research PSG nights.
- Known severe pulmonary disease (e.g., advanced chronic obstructive pulmonary disease) that, in the opinion of the investigator, may increase the risk of oxygen-induced hypercapnia.
- Unstable or clinically significant cardiopulmonary disease, including but not limited to decompensated heart failure, unstable angina, or clinically significant arrhythmia.
- Recent hospitalization (within the past 30 days) or anticipated need for hospitalization during the study period.
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- Recreational or non-prescribed opioid use.
- Alcohol use exceeding 2 standard drinks per day or evidence of substance use disorder that may interfere with study participation.
- Presence of other sleep disorders or neurologic conditions that significantly affect breathing during sleep (e.g., neuromuscular disease), in the opinion of the investigator.
- Pregnancy or breastfeeding, or planning to become pregnant during the study period.
- Positive pregnancy test at screening (serum or urine) for participants able to become pregnant. A pregnancy test will be repeated before each awake chemoreflex session or in-laboratory PSG visit; one same-day test may cover both; a positive test triggers withdrawal from further study procedures.
- Hospitalization for respiratory failure within the prior 12 months.
- Severe untreated insomnia (Insomnia Severity Index >22) likely to preclude completion of in-laboratory PSG visits.
- Inability to communicate in English sufficient for informed consent and study procedures, where a qualified interpreter consistent with UCSD HRPP policy is not available.
- Inability to tolerate nasal cannula or study procedures.
- Inability to provide informed consent or comply with study procedures.
- Any medical, psychiatric, or social condition that, in the opinion of the investigator, would interfere with safe participation or interpretation of study results.
- Prisoners or individuals who are involuntarily incarcerated.
- Inability or unwillingness to comply with research-center oxygen-safety precautions, including restrictions on smoking, vaping, open flames, and other ignition sources near oxygen equipment.
- In addition to the enrollment exclusion criteria, participants will be excluded from randomization if the following criterion is met:
- Evidence of significant hypercapnia, defined as transcutaneous carbon dioxide (TcCO2) >55 mmHg for >10 minutes during baseline polysomnography (PSG).
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site
Altman Clinical and Translational Research Institute
La Jolla, California, 92037
Bernadette e Cale, RN, MSN, (858)-822-1717, bcale@health.ucsd.edu
About this study
Official title: Opioid Physiology and Individual Outcomes With Supplemental O₂ (OPIO2)
This study will evaluate whether supplemental oxygen given during sleep improves breathing stability and sleep-disordered breathing in adults who use prescription opioids long term.
Participants will receive both supplemental oxygen and sham air during separate overnight sleep studies in a randomized order. The two study conditions will be separated by a washout period of approximately one week. Researchers will compare breathing during sleep with supplemental oxygen versus sham air and will also evaluate measures of oxygen levels, carbon dioxide levels, sleep quality, alertness, and other aspects of breathing and sleep.
For participants who previously took part in the GENESIS study, qualifying assessments from that study may be used to meet certain baseline requirements when appropriate, which may reduce the need to repeat some testing.
Read the detailed description
This is a Phase II, single-center, randomized, double-blind, sham-controlled crossover study evaluating the effects of nocturnal supplemental oxygen on ventilatory stability and sleep-disordered breathing in adults receiving chronic opioid therapy.
Eligible participants will be randomized to one of two treatment sequences: supplemental oxygen followed by sham air, or sham air followed by supplemental oxygen. Each intervention will be administered during a separate in-laboratory overnight polysomnography (PSG) visit, with an approximately 1-week washout period between intervention nights. Each participant will therefore receive both study conditions and serve as their own control.
The study will evaluate the effect of supplemental oxygen on flow-based apnea-hypopnea index (AHIflow) and other measures of respiratory physiology, sleep-disordered breathing, oxygenation, carbon dioxide levels, neurobehavioral performance, and patient-reported sleep outcomes.
Most participants are expected to have previously enrolled in the GENESIS study (IRB #814091). When appropriate, qualifying assessments previously completed through GENESIS may be used to satisfy corresponding OPIO2 baseline requirements. OPIO2 informed consent, confirmation of current eligibility, and any required missing or repeat assessments must be completed before randomization.
- Conditions
- Sleep-disordered Breathing, Chronic Opioid Use
- Being tested
- Sham Air, Supplemental Oxygen
- Keywords
- Supplemental Oxygen, Sleep-Disordered Breathing, Chronic Opioid Use, Central Sleep Apnea, Obstructive Sleep Apnea, Ventilatory Instability, Loop Gain, Polysomnography, Nocturnal Hypoxemia
- Medical subject headings
- Sleep Apnea Syndromes, Sleep Apnea, Central, Sleep Apnea, Obstructive
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Sham AirOther
Sham air will be delivered during sleep through a nasal cannula using a standard wall air flow controller during an in-laboratory overnight polysomnography (PSG). Sham air will be delivered at a fixed flow rate of 4 L/min and may be reduced to 3 L/min for participant comfort.
Supplemental OxygenDrug
Supplemental oxygen will be delivered during sleep through a nasal cannula using a standard wall oxygen flow controller during an in-laboratory overnight polysomnography (PSG). Supplemental oxygen will be delivered at a fixed flow rate of 4 L/min and may be reduced to 3 L/min for participant comfort.
| Study group | Role | What they receive |
|---|---|---|
| Sham Air Followed by Supplemental Oxygen | Experimental | Participants will receive sham air during the first in-laboratory overnight polysomnography (PSG) visit, followed by an approximately 1-week washout period, and then receive supplemental oxygen during the second in-laboratory overnight PSG visit. Receives: Other: Sham Air; Drug: Supplemental Oxygen |
| Supplemental Oxygen Followed by Sham Air | Experimental | Participants will receive supplemental oxygen during the first in-laboratory overnight polysomnography (PSG) visit, followed by an approximately 1-week washout period. Participants will then receive sham air during the second in-laboratory overnight PSG visit. Receives: Other: Sham Air; Drug: Supplemental Oxygen |
What is being measured
The primary outcome is the main question the study is designed to answer.
Flow-Based Apnea-Hypopnea Index (AHIflow)
AHIflow is the number of apneas lasting at least 10 seconds plus airflow-reduction events with a greater than 30% reduction in airflow lasting at least 10 seconds, divided by total sleep time in hours. Each respiratory event is counted once. Oxygen desaturation or arousal is not required. AHIflow will be measured during each intervention PSG, and the primary treatment comparison will be the within-participant difference between the supplemental oxygen and sham air conditions.
Measured: During each overnight intervention PSG, approximately 1 week apart
Secondary outcomes (1)
Loop Gain
Loop gain is a dimensionless measure of ventilatory control instability estimated from overnight polysomnography (PSG) data. Loop gain will be assessed during each intervention PSG to evaluate the effect of supplemental oxygen compared with sham air on ventilatory control.
Measured: During each overnight intervention PSG, approximately 1 week apart
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Nov 2026
- Study start1 Dec 2026 (estimated)
- Primary completion1 Dec 2031 (estimated)
- Study completion1 Dec 2031 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Sleep-disordered BreathingStudies of the same condition, open and under way.
- More trials run by University of California, San DiegoThe 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 2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Participants will be randomized 1:1 to one of two treatment sequences: supplemental oxygen followed by sham air, or sham air followed by supplemental oxygen. Each participant will receive both interventions during separate in-laboratory overnight polysomnography visits, with an approximately 1-week washout period between intervention nights.
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 62 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of California, San Diego
- Sponsor type
- University, hospital or other
- Collaborators
- National Heart, Lung, and Blood Institute (NHLBI)
- Responsible party
- Principal investigator, Jeremy Orr, M.D., University of California, San Diego
- Investigators
- Jeremy Orr, MD, Principal investigator, University of California, San Diego
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07923760
- Sponsor's protocol ID
- 814959
- Other IDs
- R01HL179220
- Acronym
- OPIO2
- Status last verified
- Sep 2026
- First submitted
- 16 Oct 2026
- Last updated
- 6 Nov 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: De-identified individual participant data generated under this protocol may be shared with collaborators or repositories, as permitted by the informed consent document, UC San Diego IRB/HRPP requirements, NIH/NHLBI data-sharing requirements, institutional policy, and applicable data-use agreements. Shared datasets will not include direct identifiers unless specifically approved by the IRB/HRPP and permitted by the informed consent document.
Study at a glance
From the registry record, last updated by the sponsor on 6 Nov 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Opioid Physiology and Individual Outcomes With Supplemental O₂ (OPIO2)
- ClinicalTrials.gov ID
- NCT07923760
- Acronym / sponsor ID
- OPIO2 / 814959
- Conditions
- Sleep-disordered Breathing, Chronic Opioid Use
- Keywords
- Supplemental Oxygen, Sleep-Disordered Breathing, Chronic Opioid Use, Central Sleep Apnea, Obstructive Sleep Apnea, Ventilatory Instability, Loop Gain, Polysomnography
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 62 participants (estimated)
- Lead sponsor
- University of California, San DiegoUniversity, hospital or other
- Collaborators
- National Heart, Lung, and Blood Institute (NHLBI)
- Study start
- 1 Dec 2026 (estimated)
- Primary completion
- 1 Dec 2031 (estimated)
- Study completion
- 1 Dec 2031 (estimated)
- First posted
- 6 Nov 2026 (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.
This study will evaluate whether supplemental oxygen given during sleep improves breathing stability and sleep-disordered breathing in adults who use prescription opioids long term.
Participants will receive both supplemental oxygen and sham air during separate overnight sleep studies in a randomized order. The two study conditions will be separated by a washout period of approximately one week. Researchers will compare breathing during sleep with supplemental oxygen versus sham air and will also evaluate measures of oxygen levels, carbon dioxide levels, sleep quality, alertness, and other aspects of breathing and sleep.
For participants who previously took part in the GENESIS study, qualifying assessments from that study may be used to meet certain baseline requirements when appropriate, which may reduce the need to repeat some testing.
Detailed description
This is a Phase II, single-center, randomized, double-blind, sham-controlled crossover study evaluating the effects of nocturnal supplemental oxygen on ventilatory stability and sleep-disordered breathing in adults receiving chronic opioid therapy.
Eligible participants will be randomized to one of two treatment sequences: supplemental oxygen followed by sham air, or sham air followed by supplemental oxygen. Each intervention will be administered during a separate in-laboratory overnight polysomnography (PSG) visit, with an approximately 1-week washout period between intervention nights. Each participant will therefore receive both study conditions and serve as their own control.
The study will evaluate the effect of supplemental oxygen on flow-based apnea-hypopnea index (AHIflow) and other measures of respiratory physiology, sleep-disordered breathing, oxygenation, carbon dioxide levels, neurobehavioral performance, and patient-reported sleep outcomes.
Most participants are expected to have previously enrolled in the GENESIS study (IRB #814091). When appropriate, qualifying assessments previously completed through GENESIS may be used to satisfy corresponding OPIO2 baseline requirements. OPIO2 informed consent, confirmation of current eligibility, and any required missing or repeat assessments must be completed before randomization.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 2
- Model description
- Participants will be randomized 1:1 to one of two treatment sequences: supplemental oxygen followed by sham air, or sham air followed by supplemental oxygen. Each participant will receive both interventions during separate in-laboratory overnight polysomnography visits, with an approximately 1-week washout period between intervention nights.
| Arm | Type | Receives |
|---|---|---|
| Sham Air Followed by Supplemental Oxygen | Experimental | Other: Sham Air, Drug: Supplemental OxygenParticipants will receive sham air during the first in-laboratory overnight polysomnography (PSG) visit, followed by an approximately 1-week washout period, and then receive supplemental oxygen during the second in-laboratory overnight PSG visit. |
| Supplemental Oxygen Followed by Sham Air | Experimental | Other: Sham Air, Drug: Supplemental OxygenParticipants will receive supplemental oxygen during the first in-laboratory overnight polysomnography (PSG) visit, followed by an approximately 1-week washout period. Participants will then receive sham air during the second in-laboratory overnight PSG visit. |
Who may qualify
- Ages
- 18 to 75 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (8 listed)
- Age 18 to 75 years.
- Chronic opioid use for ≥3 months with a daily opioid dose equivalent to at least 20 mg of oral morphine (morphine equivalent daily dose [MEqD]). Examples include approximately 13 mg oxycodone, 20 mg hydrocodone, 100 mg tramadol, or equivalent doses of other opioids.
- Ability and willingness to comply with study procedures, including overnight laboratory polysomnography and administration of oxygen or sham air in the laboratory.
- Ability to provide written informed consent.
- For participants able to become pregnant: agreement to use an effective contraceptive method (e.g., a licensed hormonal or intrauterine method, or an effective barrier method) during study participation. The study team will review and document the method before enrollment.
Key exclusion criteria (21 listed)
- Body mass index (BMI) >35 kg/m².
- Requirement for supplemental oxygen therapy outside of the study.
- Current use of CPAP or other sleep-apnea treatment that cannot safely be withheld during OPIO2 research PSG nights.
- Known severe pulmonary disease (e.g., advanced chronic obstructive pulmonary disease) that, in the opinion of the investigator, may increase the risk of oxygen-induced hypercapnia.
- Unstable or clinically significant cardiopulmonary disease, including but not limited to decompensated heart failure, unstable angina, or clinically significant arrhythmia.
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 |
|---|---|---|
| Sham AirSham air will be delivered during sleep through a nasal cannula using a standard wall air flow controller during an in-laboratory overnight polysomnography (PSG). Sham air will be delivered at a fixed flow rate of 4 L/min and may be reduced to 3 L/min for participant comfort. | Other | Sham Air Followed by Supplemental Oxygen, Supplemental Oxygen Followed by Sham Air |
| Supplemental OxygenSupplemental oxygen will be delivered during sleep through a nasal cannula using a standard wall oxygen flow controller during an in-laboratory overnight polysomnography (PSG). Supplemental oxygen will be delivered at a fixed flow rate of 4 L/min and may be reduced to 3 L/min for participant comfort. | Drug | Sham Air Followed by Supplemental Oxygen, Supplemental Oxygen Followed by Sham Air |
Primary outcome
Flow-Based Apnea-Hypopnea Index (AHIflow)
Time frame: During each overnight intervention PSG, approximately 1 week apart
AHIflow is the number of apneas lasting at least 10 seconds plus airflow-reduction events with a greater than 30% reduction in airflow lasting at least 10 seconds, divided by total sleep time in hours. Each respiratory event is counted once. Oxygen desaturation or arousal is not required. AHIflow will be measured during each intervention PSG, and the primary treatment comparison will be the within-participant difference between the supplemental oxygen and sham air conditions.
1 secondary outcome
Loop Gain
Time frame: During each overnight intervention PSG, approximately 1 week apart
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 6 Nov 2026.
- Individual participant dataSharing planned: Yes. De-identified individual participant data generated under this protocol may be shared with collaborators or repositories, as permitted by the informed consent document, UC San Diego IRB/HRPP requirements, NIH/NHLBI data-sharing requirements, institutional policy, and applicable data-use agreements. Shared datasets will not include direct identifiers unless specifically approved by the IRB/HRPP and permitted by the informed consent document.
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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.
Jeremy Orr, MD principal investigator
University of California, San Diego
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing Supplemental Oxygen in people with Sleep-disordered Breathing and Chronic Opioid Use, run by University of California, San Diego 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 8 inclusion and 21 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 6 Nov 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.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
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 Stacie L Moore, CRT-SDS (6197356727, s3moore@health.ucsd.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Flow-Based Apnea-Hypopnea Index (AHIflow) (time frame: During each overnight intervention PSG, approximately 1 week apart). 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 6 Nov 2026.