About this trial
Obstructive sleep apnea (OSA) is a highly prevalent disorder that has major consequences for cardiovascular health, neurocognitive function, risk of traffic accidents, daytime sleepiness, and quality of life. For years, a "classic" model of OSA has been used to describe the disorder, which fails to capture it's complexity. Recently, a model for OSA called drive-dependent OSA was discovered be more prevalent in the OSA population. The drive-dependent subgroup benefits exclusively from increased ventilation, increased dilator muscle activity, and reduced event risk when drive spontaneously rises. This study seeks to provide direct evidence that reducing the loss of drive prevents the loss of ventilation, pharyngeal muscle activity, and thus the onset of OSA respiratory events, specifically in "drive-dependent" but not "classic" OSA. This will be achieved using CO2 delivered at precise times during breaths in sleep to prevent loss of overall ventilatory drive.
Eligibility criteria
Qualifiers
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.
Disqualifiers
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
Trial design
Treatments tested in this trial
- Dynamic CO2
- Sham CO2