CPAP in Patients With Severe Obesity After Anesthesia

Assessment of Cardiopulmonary Function in Response to Continuous Positive Airway Pressure in Patients With Severe Obesity After Anesthesia

The goal of this study is to compare two continuous positive airway pressure (CPAP) settings on heart and lung function in patients with severe obesity after anesthesia. The main questions it aims to answer are:

1. Does a recruitment maneuver and CPAP set to intrathoracic pressure (ITP) improve cardiopulmonary function compared to standard CPAP settings in patients with severe obesity after anesthesia?
2. Does the location of adipose tissue influence the response to CPAP settings in patients with severe obesity after anesthesia?

Participants will undergo monitoring of their intrathoracic pressure using an esophageal catheter. In the recovery area after anesthesia, participants will receive two CPAP settings, each for 20 minutes.

• Intervention 1: Recruitment maneuver and CPAP will set to the level of intrathoracic pressure
• Intervention 2: CPAP set to home settings (if OSA is present) or between 8-10 cmH20 (if OSA is not present).

Study Overview

• Status: Not yet recruiting
• Conditions: Anesthesia Morbidity; Obesity, Abdominal; Ventilator Lung; Apnea, Obstructive Sleep; Atelectases, Postoperative Pulmonary
• Intervention / Treatment: Device: Recruitment/ITP-CPAP (Intervention A); Device: Standard CPAP (Intervention B); Device: Atmospheric Pressure

Detailed Description

The current proposed crossover study is a single center, open-label clinical trial in patients who have severe obesity (defined by body mass index greater than or equal to 40 kg/m2) and are recovering from anesthesia. The primary aim is to describe the difference cardiopulmonary function between two settings for continuous positive airway pressure (CPAP), using electrical impedance tomography (EIT), transthoracic echocardiography, and esophageal pressure monitoring to measure response. The secondary aim is to determine whether the location of adipose tissue modifies responses to CPAP settings.

The study protocol consists of placing an esophageal catheter to monitor intrathoracic pressure in the operating room when the participant is under anesthesia. In the post-anesthesia care unit, participants will receive two CPAP settings, in random order, for 20 minutes each. One setting is a recruitment maneuver and CPAP set to the level of end-expiratory pressure (intrathoracic pressure). Another setting is a CPAP set to home levels (if known) or 8-10 cmH20 if not on home CPAP. There will be a 10 minute washout period between interventions. Investigators will monitor airway and esophageal pressure, ventilation with electrical impedance tomography, right heart function with transthoracic echocardiography, and abdominal muscle contraction with ultrasound. Waist and hip circumference will be measured prior to CPAP.

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Timothy Gaulton, MD, MSc; Phone Number: 617-643-7733; Email: tgaulton@mgh.harvard.edu
• Study Contact Backup: Name: Lorenzo Berra; Email: lberra@mgh.harvard.edu

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

1. Adult patients (≥ 18 years old) scheduled for elective non-cardiothoracic surgery requiring general anesthesia with an endotracheal tube
2. Planned admission to the post-anesthesia care unit (PACU) after surgery
3. BMI ≥ 40 kg/m2

4. At the time of baseline measurements in the PACU, patients meet the following criteria:

   • Receiving ≤ 6 liters of supplemental nasal cannula oxygen
   • Alert as defined by a Richmond Agitation Sedation Scale of 0 or -1
   • Oriented to person, place, and time

Exclusion Criteria:

1. Pregnancy, suspected pregnancy or less than six weeks postpartum Known or current pneumothorax

2. Hemodynamic instability at the time of study assessment in the PACU defined as:

   • systolic blood pressure <90 mmHg or >180 mmHg
   • mean blood pressure <60 or >130 mmHg
   • Any use of intravenous vasoactive agent
   • heart rate < 50 or > 120 beats per minute

3. Respiratory insufficiency in PACU defined as:

   • Respiratory rate > 30
   • Oxygen saturation < 92%
   • Receiving > 6 liters of supplemental oxygen
4. Known chronic lung disease requiring supplemental oxygen at home
5. Known systolic heart dysfunction (left ventricular ejection fraction ≤ 30%)

6. Contraindication for esophageal catheter placement:

   • Known esophageal varices
   • Known bacterial sinusitis
   • Recent esophageal, nasopharyngeal, or laryngeal trauma or surgery
   • Known coagulopathy: including history of thrombocytopenia defined as platelet count <50,000; presence of hemophilia; known genetic disorder of coagulation (e.g.,deficits of protein C, protein S, von Willebrand factor) or oral and subcutaneous anticoagulation treatment (e.g., heparin, warfarin, and or other oral anticoagulants)

7. Contraindication for electrical impedance tomograph belt placement:

   • Pacemaker and/or internal cardiac defibrillator
   • Chest skin injury
8. Concern for study inclusion by the perioperative nurse or anesthesia team

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Recruitment and ITP-CPAP; Recruitment maneuver followed by CPAP set to intrathoracic pressure (ITP)	Device: Recruitment/ITP-CPAP (Intervention A); Participant will receive a recruitment maneuver followed by CPAP set to the level of end-expiratory esophageal pressure (measured during atmospheric pressure breathing). The intervention will last for 20 minutes.
Active Comparator: Standard CPAP; CPAP set to home level of CPAP (if known) or CPAP set to standard levels (8-10 cmH20)	Device: Standard CPAP (Intervention B); Participant will receive their home CPAP (if on CPAP at home) or CPAP at 8-10 cmH20 (if not on CPAP at home or no known diagnosis of OSA). The intervention will last for 20 minutes.
Placebo Comparator: Atmospheric pressure; Breathing without CPAP	Device: Atmospheric Pressure; Participant will breathe at atmosphere pressure (no CPAP) with supplemental oxygen as needed per clinical guidance.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
End expiratory lung impedance	End expiratory lung impedance, a surrogate of end expiratory lung volume, measured from EIT	Assessed at baseline during atmospheric pressure breathing (no CPAP), assessed at the end of intervention A (20 minutes), assessed at end of intervention B (20 minutes)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Regional lung ventilation	% of relative ventilation to ventral and dorsal lung regions, measured from EIT	Assessed at baseline during atmospheric pressure breathing (no CPAP), assessed at the end of intervention A (20 minutes), assessed at end of intervention B (20 minutes)
Right ventricular function	Defined by tricuspid annular plane systolic excursion, measured from transthoracic echocardiogram	Assessed at baseline during atmospheric pressure breathing (no CPAP), assessed at the end of intervention A (20 minutes), assessed at end of intervention B (20 minutes)
Mean pulmonary artery pressure	Defined by pulmonary artery acceleration time using transthoracic echocardiography	Assessed at baseline during atmospheric pressure breathing (no CPAP), assessed at the end of intervention A (20 minutes), assessed at end of intervention B (20 minutes)
Inspiratory effort	delta esophageal pressure, calculated as the negative deflections of esophageal pressure from the onset of inspiration and Pressure time product, the time-based integral of the Pes tracing during inspiration, per breath and per minute, measured from esophageal pressure tracing	Assessed at baseline during atmospheric pressure breathing (no CPAP), assessed at the end of intervention A (20 minutes), assessed at end of intervention B (20 minutes)
Abdominal muscle thickness	Thickness of the muscles involved in expiration, measured by ultrasound - lateral abdominal wall muscles (external oblique, internal oblique, and transversus abdominis muscles)	Assessed at baseline during atmospheric pressure breathing (no CPAP), assessed at the end of intervention A (20 minutes), assessed at end of intervention B (20 minutes)
Respiratory rate	breath per minute	Assessed at baseline during atmospheric pressure breathing (no CPAP), assessed at the end of intervention A (20 minutes), assessed at end of intervention B (20 minutes)
Oxygen saturation	Defined from pulse oximetry	Assessed at baseline during atmospheric pressure breathing (no CPAP), assessed at the end of intervention A (20 minutes), assessed at end of intervention B (20 minutes)
Systemic blood pressure	Defined by non-invasive blood pressure measurement	Assessed at baseline during atmospheric pressure breathing (no CPAP), assessed at the end of intervention A (20 minutes), assessed at end of intervention B (20 minutes)

Collaborators and Investigators

• Sponsor: Massachusetts General Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): November 1, 2026
• Study Completion (Estimated): June 1, 2027

Study Registration Dates

• First Submitted: February 16, 2024
• First Submitted That Met QC Criteria: February 23, 2024
• First Posted (Actual): March 1, 2024

Study Record Updates

• Last Update Posted (Actual): November 18, 2025
• Last Update Submitted That Met QC Criteria: November 17, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Keywords: clinical trial; continuous positive airway pressure; transthoracic echocardiography; electrical impedance tomography; crossover studies; esophageal pressure monitoring
• Additional Relevant MeSH Terms: Nervous System Diseases; Nutrition Disorders; Overnutrition; Body Weight; Respiratory Tract Diseases; Lung Diseases; Respiration Disorders; Sleep Wake Disorders; Overweight; Apnea; Sleep Disorders, Intrinsic; Dyssomnias; Sleep Apnea Syndromes; Obesity; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Sleep Apnea, Obstructive; Pulmonary Atelectasis; Obesity, Abdominal
• Other Study ID Numbers: 2024P000451

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: All data analysis codes developed for this project in MATLAB (for electrical impedance tomography) or R will be thoroughly documented and made openly accessible on GitHub. We will make de-identified data available via the vivli platform (http://vivli.org/), non-profit clinical research data sharing platform. All data will be shared publicly under a data use agreement through a managed access process.
• IPD Sharing Time Frame: Individual participant data and supporting information will be available after data analysis and manuscript publication.
• IPD Sharing Access Criteria: Individual participant data can be accessed from a data use agreement once data is uploaded on vivil
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No