Assessment of Circuit Rebreathing During CPAP Therapy

Assessment of Circuit Rebreathing During Continuous Positive Airway Pressure (CPAP) Therapy

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).

Study Overview

• Status: Recruiting
• Conditions: Obstructive Sleep Apnea (OSA)
• Intervention / Treatment: Device: Continuous positive airway pressure (CPAP); Other: Mask exhaust port flow

Detailed 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.

• Study Type: Interventional
• Enrollment (Estimated): 13
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Scott A Sands, PhD; Phone Number: 6172780911; Email: sasands@bwh.harvard.edu
• Study Contact Backup: Name: Atqiya Aishah, PhD; Phone Number: 857 396 3808; Email: aaishah@bwh.harvard.edu

Study Locations

• United States
  • Massachusetts
    • Boston, Massachusetts, United States, 02115
      • Recruiting
      • Brigham and Women's Hospital
      • Contact: Atqiya Aishah, PhD; Phone Number: 857 396 3808; Email: aaishah@bwh.harvard.edu
      • Contact: Scott A Sands, PhD; Phone Number: 617 278 0911; Email: sasands@bwh.harvard.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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 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 Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Sequential Assignment
• Masking: Single

Number of Arms

11

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: 5 cmH2O with 35L/s; 35 L/s exhaust flow with 5 cmH₂O PAP	Device: Continuous positive airway pressure (CPAP); Subjects will be administered either 0, 5 or 10 cmH2O; Other: Mask exhaust port flow; Subjects will be administered varying levels of exhaust flow: 35, 23, 18, 13 and 8 L/s
Experimental: 5 cmH2O with 23L/s; 23 L/s exhaust flow with 5 cmH₂O PAP	Device: Continuous positive airway pressure (CPAP); Subjects will be administered either 0, 5 or 10 cmH2O; Other: Mask exhaust port flow; Subjects will be administered varying levels of exhaust flow: 35, 23, 18, 13 and 8 L/s
Experimental: 5 cmH2O with 18L/s; 18 L/s exhaust flow with 5 cmH₂O PAP	Device: Continuous positive airway pressure (CPAP); Subjects will be administered either 0, 5 or 10 cmH2O; Other: Mask exhaust port flow; Subjects will be administered varying levels of exhaust flow: 35, 23, 18, 13 and 8 L/s
Experimental: 5 cmH2O with 13L/s; 13 L/s exhaust flow with 5 cmH₂O PAP	Device: Continuous positive airway pressure (CPAP); Subjects will be administered either 0, 5 or 10 cmH2O; Other: Mask exhaust port flow; Subjects will be administered varying levels of exhaust flow: 35, 23, 18, 13 and 8 L/s
Experimental: 5 cmH2O with 8L/s; 8 L/s exhaust flow with 5 cmH₂O PAP	Device: Continuous positive airway pressure (CPAP); Subjects will be administered either 0, 5 or 10 cmH2O; Other: Mask exhaust port flow; Subjects will be administered varying levels of exhaust flow: 35, 23, 18, 13 and 8 L/s
Placebo Comparator: 0 cmH2O with 35L/s; 35 L/s exhaust flow with 0 cmH₂O PAP	Other: Mask exhaust port flow; Subjects will be administered varying levels of exhaust flow: 35, 23, 18, 13 and 8 L/s
Experimental: 10 cmH2O with 35L/s; 35 L/s exhaust flow with 10 cmH₂O PAP	Device: Continuous positive airway pressure (CPAP); Subjects will be administered either 0, 5 or 10 cmH2O; Other: Mask exhaust port flow; Subjects will be administered varying levels of exhaust flow: 35, 23, 18, 13 and 8 L/s
Experimental: 10 cmH2O with 23L/s; 23 L/s exhaust flow with 10 cmH₂O PAP	Device: Continuous positive airway pressure (CPAP); Subjects will be administered either 0, 5 or 10 cmH2O; Other: Mask exhaust port flow; Subjects will be administered varying levels of exhaust flow: 35, 23, 18, 13 and 8 L/s
Experimental: 10 cmH2O with 18L/s; 18 L/s exhaust flow with 10 cmH₂O PAP	Device: Continuous positive airway pressure (CPAP); Subjects will be administered either 0, 5 or 10 cmH2O; Other: Mask exhaust port flow; Subjects will be administered varying levels of exhaust flow: 35, 23, 18, 13 and 8 L/s
Experimental: 10 cmH2O with 13L/s; 13 L/s exhaust flow with 10 cmH₂O PAP	Device: Continuous positive airway pressure (CPAP); Subjects will be administered either 0, 5 or 10 cmH2O; Other: Mask exhaust port flow; Subjects will be administered varying levels of exhaust flow: 35, 23, 18, 13 and 8 L/s
Experimental: 10 cmH2O with 8L/s; 8 L/s exhaust flow with 10 cmH₂O PAP	Device: Continuous positive airway pressure (CPAP); Subjects will be administered either 0, 5 or 10 cmH2O; Other: Mask exhaust port flow; Subjects will be administered varying levels of exhaust flow: 35, 23, 18, 13 and 8 L/s

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in flow-adjusted average inspired oxygen fraction (FiO₂) during wake.	Difference in FiO2 between 23L/s vs 13L/s exhaust flow at 5 cmH2O PAP.	through study completion, an average of 1 year
Change in flow-adjusted average inspired oxygen fraction (FiO₂) during sleep.	Difference in FiO2 between 23L/s vs 13L/s exhaust flow at 5 cmH2O PAP.	through study completion, an average of 1 year

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Impact on hypoxic burden during sleep.	Difference in hyboxic burden between 23L/s vs 13L/s exhaust flow at 5 cmH2O PAP.	through study completion, an average of 1 year

Collaborators and Investigators

• Sponsor: Brigham and Women's Hospital
• Collaborators: Sleep Res, Inc.
• Investigators: Principal Investigator: Atqiya Aishah, PhD, Harvard Medical School & Brigham and Women's Hospital

Study record dates

Study Major Dates

• Study Start (Actual): May 27, 2025
• Primary Completion (Estimated): December 1, 2025
• Study Completion (Estimated): December 1, 2025

Study Registration Dates

• First Submitted: May 27, 2025
• First Submitted That Met QC Criteria: July 10, 2025
• First Posted (Actual): July 14, 2025

Study Record Updates

• Last Update Posted (Actual): July 14, 2025
• Last Update Submitted That Met QC Criteria: July 10, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Keywords: Obstructive sleep apnea
• Additional Relevant MeSH Terms: Nervous System Diseases; Respiratory Tract Diseases; Respiration Disorders; Sleep Wake Disorders; Apnea; Sleep Disorders, Intrinsic; Dyssomnias; Sleep Apnea Syndromes; Sleep Apnea, Obstructive
• Other Study ID Numbers: 2025P000798

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Deidentified subject data will be available upon request.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: Yes