Investigating the effects of CO2 on obstructive sleep apnea

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

This study focuses on obstructive sleep apnea (OSA), particularly a newly identified subgroup known as drive-dependent OSA. It aims to provide evidence that administering CO2 at specific times during sleep can prevent the decline in ventilatory drive, thereby reducing the occurrence of OSA events. Participants will undergo a series of assessments, including a baseline sleep study and an overnight physiological intervention, to measure the impact of CO2 on ventilatory drive and upper airway muscle activity. The study will involve both patients diagnosed with OSA and those suspected of having it, using advanced physiological measurements to evaluate outcomes.

Why it matters

Who can join: the full rules

Inclusion Criteria:

* Diagnosed OSA (AHI≥15 events/h reported in a PSG performed within 1 year) or Suspected OSA (snoring, sleepiness, witnessed apneas, other clinical symptoms)
* Use of CPAP or other therapies is acceptable; individuals will be asked to withhold treatment for 3 days before each study visit. Individuals who are occupational drivers or operate heavy machinery will not be asked to withhold treatment.

Exclusion Criteria:

* Any unstable medical conditions
* Conditions that could meaningfully raise the cardiovascular risks of brief low-dose hypercapnic-hypoxic inspired gas mixture: heart failure (LVEF\<45% if known), recent cardiovascular event (\<12 mo), recent cerebrovascular event (\<12 mo)\*
* Medications known to depress ventilatory drive (e.g. opioids, barbiturates)
* Conditions likely to increase arousability from sleep: insomnia
* Other sleep disorders that may complicate establishment of sleep: periodic limb movements (periodic limb movement arousal index \> 10/hr), narcolepsy, or parasomnias
* For intramuscular electrodes and catheter: allergy to lidocaine
* Highly-sensitive gag reflex. Patients with a self-reported 'highly-sensitive gag reflex', including an affirmative response to 'Do you sometimes gag when brushing your teeth?', will not take part in the physiology studies given the placement of an esophageal catheter
* For intramuscular electrodes: use of aspirin or other oral anti-platelets / anti-coagulants
* For oronasal mask: severe claustrophobia
* Pregnancy or nursing

  * We do not intend to exclude patients with controlled cardiovascular disease (hypertension of any severity, arrhythmias, stents) common in the OSA patient population. The transient gas mixture interventions are mild, short-lived, and act to slow the spontaneous recovery of blood gas levels to prevent cyclic upper airway obstruction as opposed to exacerbating them. Control of breathing studies commonly increase inspired CO2/reduce inspired oxygen (using higher concentrations via rebreathing tests for longer durations) in patients with a range of comorbidities including heart failure. The level of hypercapnic-hypoxia used is equivalent to taking slightly smaller breaths (by about a third, for the standard dose gas mixture 2%CO2/18.5%O2) for several breaths, or skipping a breath (for the highest dose gas mixture 6%CO2/14%O2), physiological changes that typically cause no noticeable oxygen desaturation, and are minimal compared with the effects of the larger ventilation reduction that accompanies OSA.

Where it's running

• Brigham and Women's Hospital
  Boston, Massachusetts, United States Recruiting

Study contacts

• Principal investigator: Scott Sands, PhD — Brigham and Women's Hospital and Harvard Medical School
• Study coordinator: Scott Sands, PhD
• Email: sasands@bwh.harvard.edu
• Phone: 8579280341

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.