Effect of CPAP Versus APAP in Patients With Obesity Undergoing Bariatric Surgery Protocol (ObesAOS)

July 17, 2025 updated by: Laura Pozuelo Sánchez, Hospital Universitario Ramon y Cajal

Introduction Obstructive sleep apnea (OSA) is a common disorder in obese patients, especially those undergoing bariatric surgery. OSA is characterized by upper airway obstruction during sleep, leading to intermittent hypoxia and sleep fragmentation. Obesity and OSA are closely related conditions that can exacerbate each other. Positive airway pressure therapy is essential for managing OSA, but adherence to therapy can be challenging, particularly in patients who experience rapid physiological changes after bariatric surgery.

Objective This study aims to determine whether automatic positive airway pressure therapy (APAP) improves nightly usage hours compared to continuous positive airway pressure therapy (CPAP) in obese patients undergoing bariatric surgery. Secondary objectives include evaluating the percentage of nights with therapy use over 4 hours, reduction of the residual apnea-hypopnea index (AHI), changes in daytime sleepiness, pressure requirements, side effects, sleep-related quality of life, reduction in in-person visits, and optimization of healthcare resources.

Methodology A randomized, parallel-group, open-label, controlled clinical trial will be conducted. Adult patients eligible for bariatric surgery with a diagnosis of moderate to severe OSA (AHI > 15) requiring positive pressure therapy will be included. Participants will be randomized to receive either APAP or CPAP. Follow-up will be conducted over 12 months after surgery, with assessments at 3, 6, and 12 months. Data will be collected on treatment adherence, residual AHI, OSA symptoms, daytime sleepiness, quality of life, and treatment costs.

APAP therapy is expected to improve nightly usage hours compared to CPAP. It is also expected that APAP will show better adaptation to changing pressure needs after bariatric surgery. Data will be analyzed to evaluate the effectiveness and cost-efficiency of both therapies.

This study will provide evidence on the efficacy of APAP compared to CPAP in obese patients undergoing bariatric surgery. The results will help optimize the treatment of OSA in this population and improve patients' quality of life. Additionally, the study is expected to contribute to the optimization of healthcare resources by reducing in-person visits and repeated sleep studies.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

104

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

  • Name: Laura Pozuelo- Sánchez, Nurse
  • Phone Number: 489059 913368000
  • Email: utrs.ryc@gmail.com

Study Contact Backup

Study Locations

  • Spain
      • Madrid, Spain, 28034
        • Hospital Universitario Ramón y Cajal,
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Subjects aged 18 to 80 years who meet the criteria for bariatric surgery and are on the surgical waiting list after approval by the bariatric surgery committee (BMI ≥35, or BMI ≥30 with comorbidities).
  • Diagnosis of moderate or severe sleep apnea, defined by an Apnea-Hypopnea Index (AHI) >15, requiring treatment according to protocol ("Patients with an AHI of 15 or higher will be treated with CPAP if they have hypertension, excessive daytime sleepiness, or sleep-related symptoms not explained by other causes" [17]).
  • Patients must be able to read and understand the informed consent and provide signed consent.

Exclusion Criteria:

  • Patients with central sleep apnea or periodic breathing
  • Patients with any active neoplasm
  • Patients with severe uncontrolled psychiatric disorders, alcoholism, or active drug addiction
  • Patients with unacceptable surgical/anesthetic risk
  • Patients who have undergone previous surgery for OSA or who have been treated with positive airway pressure and did not tolerate it

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: APAP Group
APAP Group: They will receive treatment with AutoCPAP. The device automatically adjusts the air pressure according to the patient's needs, and usage data and respiratory events will be manually collected at each visit.
Device: In the intervention group, patients will be treated with auto-adjusting APAP, providing variable pressures throughout the sleep hours.
AutoCPAP will be prescribed to patients undergoing bariatric surgery.
Other Names:
  • APAP
  • Automatic Positive Airway Pressure
Active Comparator: CPAP group
CPAP Group: They will receive treatment with conventional CPAP. The device will provide a fixed and constant air pressure, and follow-up will be conducted through in-person visits and titration with APAP after adherence to verify the optimal pressure. The initial CPAP pressure will be individually calculated using Hoffstein's formula based on parameters such as body mass index (BMI), neck circumference, and apnea-hypopnea index (AHI).
Device: CPAP
In the control group, patients will be treated with CPAP.
Other Names:
  • Continuous Positive Airway Pressure

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
APAP vs. CPAP: Impact on Nightly Usage in Obese Patients Undergoing Bariatric Surgery
Time Frame: Obese patients undergoing bariatric surgery will be evaluated during the 3 months prior to surgery and at 3, 6, and 12 months postoperatively in patients with OSA undergoing bariatric surgery.
To determine whether APAP therapy increases nightly usage hours compared to CPAP therapy in obese patients undergoing bariatric surgery. Unit of Measure: Average hours of PAP use per night (measured via device data).
Obese patients undergoing bariatric surgery will be evaluated during the 3 months prior to surgery and at 3, 6, and 12 months postoperatively in patients with OSA undergoing bariatric surgery.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Therapy Adherence Over Time
Time Frame: 3 months before bariatric surgery and at 3, 6, and 12 months postoperatively.
To measure and compare the percentage of nights with therapy usage exceeding 4 hours in both groups (APAP and fixed CPAP). Unit of Measure: Percentage of nights with ≥4 hours of PAP use.
3 months before bariatric surgery and at 3, 6, and 12 months postoperatively.
Reduction in Residual AHI
Time Frame: 3 months before bariatric surgery and at 3, 6, and 12 months postoperatively.
To evaluate the reduction in the residual Apnea-Hypopnea Index (AHI) in both groups. Unit of Measure: Residual AHI (events per hour).
3 months before bariatric surgery and at 3, 6, and 12 months postoperatively.
Daytime Sleepiness
Time Frame: 3, 6, and 12 months postoperatively
To assess changes in daytime sleepiness using validated scales (e.g., Epworth Sleepiness Scale) in both groups. Unit of Measure: Total ESS score (range: 0-24; higher scores indicate greater sleepiness).
3, 6, and 12 months postoperatively
Pressure Requirement Trends
Time Frame: (3 months pre-surgery and 3, 6, and 12 months postoperatively).

To evaluate and compare changes in positive airway pressure (PAP) requirements, measured in cm H₂O, in patients treated with APAP or CPAP over time.

Unit of Measure: Pressure level (cm H₂O).
(3 months pre-surgery and 3, 6, and 12 months postoperatively).
Pressure Adaptability of APAP
Time Frame: 3, 6, and 12 months postoperatively

To assess the adaptability of APAP therapy to varying pressure requirements over time, compared to fixed-pressure CPAP, in patients with OSA following bariatric surgery.

Unit of Measure: Variability in delivered pressure (cm H₂O).
3, 6, and 12 months postoperatively
Side Effects Monitoring
Time Frame: (3 months pre-surgery and 3, 6, and 12 months postoperatively).
To measure and compare the presence of side effects (e.g., nasal dryness, skin irritation) in both groups. Unit of Measure: Incidence of reported side effects (percentage of patients affected).
(3 months pre-surgery and 3, 6, and 12 months postoperatively).
Sleep Quality (assessed using the Pittsburgh Sleep Quality Index)
Time Frame: (3 months pre-surgery and 3, 6, and 12 months postoperatively).
To assess sleep quality using the validated Pittsburgh Sleep Quality Index (PSQI) questionnaire.in both groups. Unit of Measure: Total PSQI score (range: 0-21; higher scores indicate poorer sleep quality).
(3 months pre-surgery and 3, 6, and 12 months postoperatively).
General Quality of Life (assessed using the EuroQol-5D)
Time Frame: 3 months pre-surgery and 3, 6, and 12 months postoperatively.
To assess general quality of life using the validated EuroQol-5D (EQ-5D) questionnaire. Unit of Measure: EQ-5D Utility Index and Visual Analogue Scale (VAS) score 0-100.
3 months pre-surgery and 3, 6, and 12 months postoperatively.
Reduction in Outpatient Visits
Time Frame: (3 months pre-surgery and 3, 6, and 12 months postoperatively).
To analyze the potential reduction in outpatient clinic visits in the APAP group compared to the CPAP group. Unit of Measure: Number of outpatient visits per patient.
(3 months pre-surgery and 3, 6, and 12 months postoperatively).
Healthcare Resource Optimization
Time Frame: (3 months pre-surgery and 3, 6, and 12 months postoperatively).

To evaluate the reduction in repeated sleep studies as an indicator of healthcare resource optimization in patients treated with APAP compared to CPAP.

Unit of Measure: Number of repeated sleep studies per patient.
(3 months pre-surgery and 3, 6, and 12 months postoperatively).
STOP-BANG Questionnaire Accuracy
Time Frame: (3 months pre-surgery and 3, 6, and 12 months postoperatively).
To assess the sensitivity and specificity of the STOP-BANG questionnaire for detecting OSA in bariatric patients, and to determine whether a new cutoff point is needed to optimize its performance in this population. Unit of Measure: STOP-BANG total score (range 0 to 8); sensitivity and specificity percentages for different cutoff points.
(3 months pre-surgery and 3, 6, and 12 months postoperatively).

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Hospital Universitario Ramon y Cajal

Collaborators

Fundacion para la Investigacion Biomedica del Hospital Universitario Ramon y Cajal

Investigators

  • Principal Investigator: Laura Pozuelo-Sánchez, Nurse, Iricys

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

September 15, 2025

Primary Completion (Estimated)

September 15, 2027

Study Completion (Estimated)

September 15, 2028

Study Registration Dates

First Submitted

May 22, 2025

First Submitted That Met QC Criteria

May 22, 2025

First Posted (Actual)

June 3, 2025

Study Record Updates

Last Update Posted (Actual)

July 23, 2025

Last Update Submitted That Met QC Criteria

July 17, 2025

Last Verified

May 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 111/25

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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