Assessment of Circuit Rebreathing During CPAP Therapy

Last updated: July 10, 2025
Sponsor: Brigham and Women's Hospital
Overall Status: Active - Recruiting

Phase

N/A

Condition

Sleep Apnea Syndromes

Treatment

Mask exhaust port flow

Continuous positive airway pressure (CPAP)

Clinical Study ID

NCT07062770
2025P000798
  • Ages 21-70
  • All Genders

Study Summary

The goal of this research is to better understand how different CPAP mask designs affect airflow and rebreathing of exhaled carbon dioxide (CO₂) during sleep in individuals with obstructive sleep apnea (OSA).

Eligibility Criteria

Inclusion

Inclusion Criteria:

  • Moderate to severe OSA (AHI>20)

  • Self-reported CPAP users or have previously used CPAP

  • Self-reported holding pressure of maximum 13 cmH2O (if known)

  • Age: 21-70

  • BMI: 18-40 kg/m2

Exclusion

Exclusion Criteria:

  • Self-reported severe mouth-breathing

  • Requirement for nocturnal supplemental oxygen or other ventilatory support

  • Severe cardiovascular or pulmonary disease

  • Any unstable or acute medical condition

  • Any additional sleep disorder, including insomnia, except for OSA.

Study Design

Total Participants: 13
Treatment Group(s): 2
Primary Treatment: Mask exhaust port flow
Phase:
Study Start date:
May 27, 2025
Estimated Completion Date:
December 01, 2025

Study Description

To understand the existence and severity of circuit rebreathing during treatment with continuous positive airway pressure (CPAP) using different sizes of the exhaust ports in individuals with obstructive sleep apnea (OSA).

Flow-adjusted end-tidal oxygen (PetO2) and carbon dioxide (PetCO2) will be assessed to determine the magnitude of hypoxic load during both wakefulness and sleep. To systematically assess these conditions, the conditions were defined as follows:

  • 5A: 35 L/s exhaust flow with 5 cmH₂O PAP

  • 5B: 23 L/s exhaust flow with 5 cmH₂O PAP

  • 5C: 18 L/s exhaust flow with 5 cmH₂O PAP

  • 5D: 13 L/s exhaust flow with 5 cmH₂O PAP

  • 5E: 8 L/s exhaust flow with 5 cmH₂O PAP

  • 0P: 35 L/s exhaust flow with 0 cmH₂O PAP

  • 10A: 35 L/s exhaust flow with 10 cmH₂O PAP

  • 10B: 23 L/s exhaust flow with 10 cmH₂O PAP

  • 10C: 18 L/s exhaust flow with 10 cmH₂O PAP

  • 10D: 13 L/s exhaust flow with 10 cmH₂O PAP

  • 10E: 8 L/s exhaust flow with 10 cmH₂O PAP Primary endpoint is to evaluate the effect of exhaust flow on flow-adjusted average inspired oxygen fraction (FiO₂) during (1) wakefulness and (2) sleep between 5B vs. 5D.

Connect with a study center

  • Brigham and Women's Hospital

    Boston, Massachusetts 02115
    United States

    Active - Recruiting

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