A Phase 2 interventional study of Sham Air and Supplemental Oxygen in Sleep-disordered Breathing and Chronic Opioid Use, sponsored by University of California, San Diego. Not yet recruiting at 1 site in United States. Open to participants aged 18 Years to 75 Years. Per ClinicalTrials.gov, last updated 2026-11-06.
Sponsored by University of California, San Diego · Phase 2, Interventional, and Treatment
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.
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.
1,084 studies on the registry are indexed under Sleep Apnea Syndromes; 171 are open to participants now.
This study's planned enrollment of 62 is close to the median of 60 across 673 interventional studies indexed under Sleep Apnea Syndromes.
Browse Sleep Apnea Syndromes studies →University of California, San Diego is the lead sponsor of 980 studies on the registry; 195 are open to participants now.
Of its 113 completed or terminated interventional studies of FDA-regulated products, 71 (63%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
In addition to the enrollment criteria, participants must meet the following criterion to be eligible for randomization:
Exclusion Criteria:
In addition to the enrollment exclusion criteria, participants will be excluded from randomization if the following criterion is met:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
COPD
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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.
Other: Sham Air · Drug: Supplemental Oxygen
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.
Other: Sham Air · Drug: Supplemental Oxygen
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 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.
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.
Time frame: During each overnight intervention PSG, approximately 1 week apart
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.
Time frame: During each overnight intervention PSG, approximately 1 week apart
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: 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.
Supporting information: Study protocol
Time frame: Beginning after publication of the primary study results and available thereafter in accordance with NIH/NHLBI data-sharing requirements and applicable institutional policies.
Access criteria: Qualified researchers may request access to de-identified individual participant data for research purposes. Access will be provided only 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.
Start is estimated for Dec 2026; primary completion for Dec 2031, 60 months later.
Of 17 phase 2 interventional studies under Sleep Apnea Syndromes, half reached primary completion within 46 months of starting (the median), counting those still running; a quarter within 26 and three quarters within 56. This study's planned 60 months is above that.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Sep 2026. You cannot join it, but the record below documents what was studied.
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