Ultrasound Estimation of Gastric Volumes in Patients With Previous Gastric Sleeve

February 21, 2025 updated by: University of North Carolina, Chapel Hill

The goal of this observational study is to determine whether the existing model for calculating gastric volume based on an ultrasound-measured cross sectional area is accurate in adults who have had a previous gastric sleeve procedure. The main questions it aims to answer are:

Can the existing model accurately calculate gastric volume in patients who have had a previous gastric sleeve procedure?

If the existing model is not accurate in this population, can a model be developed to predict gastric volume in these patients based on ultrasound-measured cross section area?

Participants will be asked to fast prior to presenting for a gastric ultrasound scan. Following a fasted scan, patients will drink a small volume of water and undergo a second gastric scan.

Study Overview

Status

Completed

Conditions

Detailed Description

A major complication related to anesthesia in the perioperative period is aspiration of gastric contents. Multiple population level studies have found that aspiration among the leading causes of death from airway complications associated with anesthesia. In order to minimize the risk of aspiration, patients are often fasted prior to surgery if possible with the goal of emptying the stomach. Guidelines from the American Society of Anesthesiologists suggest that the existing evidence supports a 2 hour fast from clear fluids, a minimum of 6 hours from light foods such as toast, and even greater fasting times such as 8 hours or more from heavier foods such as meat. However, there is often a lack of clarity as to whether patients are adequately fasted prior to surgery especially elective surgery patients coming from home. This presents a dilemma of whether additional precautions need to be taken during surgery or even if the case needs to be cancelled.

One tool that has been used by anesthesiologists to clarify the risk of a full stomach preoperatively is an estimation of gastric volume using bedside ultrasound. The most commonly utilized method of estimating gastric volume is done by laying the patient in the right lateral decubitus position, measuring the diameter of stomach at the level of the antrum, and estimating a volume using the formula stomach volume (mL) = 27 + 14.6* antral cross sectional area (cm2) - 1.28*age (years). Volumes up to 1.5 mL/kg are generally thought to be consistent with baseline gastric secretions, while higher volumes or the presence of solids on ultrasound are indicative of a relatively full stomach and elevated aspiration risk. Gastric ultrasound and this method of estimating volume have been found to be very sensitive and specific for identifying a full stomach including in pregnant and severely obese patients.

Despite the proven accuracy of bedside ultrasound in estimating gastric volume in a variety of populations, all studies in the literature excluded patients who had previous gastric surgeries. There is a single published case study of an attempt to obtain an ultrasound estimate of gastric volume in a patient who had a previous roux-en-Y gastric bypass. This report found that the patient's stomach appeared to be empty on ultrasound regardless of ingested volume because the antrum of the stomach is no longer continuous with the remainder of the gastrointestinal tract after the operation. This is not the case in gastric sleeve procedures in which the greater curvature of the stomach is resected but the flow of material in the tract is left intact. Notably, an estimated 280,000 bariatric procedures were performed in the United States in 2022 with the vast majority of these being gastric sleeves. Given the large and ever increasing population of patients who have had gastric sleeve procedures and the proven utility of gastric ultrasound in assessing appropriate preoperative fasting it is important to determine whether traditional models of estimating gastric volume retain their accuracy in this population.

Participants will be asked to fast from solids for 8 hours and fluids for 2 hours prior to presenting for the study to ensure an empty stomach at baseline. They will be asked to lay on a flat surface on their right side. A curvilinear ultrasound probe will be placed on their abdomen and the antrum of the stomach will be identified with the liver and aorta in view at which point 3 measurements of both the anteroposterior and craniocaudal diameter of the stomach will be taken. These measurements will be used to calculate a gastric volume. Participants will then be asked to drink 100 mL of water. A second set of measurements of the gastric antrum will be obtained within 5 minutes of ingestion of the water as previously described. Serial measurements will be taken at thirty-minute intervals until 2 hours have past since ingestion. Participants will then be asked if they would be willing to repeat the above process at a later date. If they agree to go forward with an additional date, they will be asked to undergo the same process detailed above but with ingestion of 200 mL of water. If they are amenable to presenting a third time they will undergo a final trial with 300 mL of water as described above.

Study Type

Observational

Enrollment (Actual)

37

Contacts and Locations

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

Study Locations

  • United States
    • North Carolina
      • Chapel Hill, North Carolina, United States, 27514
        • University of North Carolina at Chapel Hill

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

Yes

Sampling Method

Non-Probability Sample

Study Population

Patients who have previously undergone gastric sleeve procedure at UNC Hospitals.

Description

Inclusion Criteria:

  • Age greater than or equal to 18 years of age
  • English speaking
  • Previous gastric sleeve procedure

Exclusion Criteria:

  • Gastric surgery in addition to gastric sleeve
  • Known hiatal hernia
  • Pregnancy

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

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Accuracy of existing gastric volume equation
Time Frame: 5 minutes after ingestion
Calculated gastric volumes from after participants ingestion of a known quantity of water during the study will be compared to the known volumes of water that the subjects ingested using a mean squared error analysis.
5 minutes after ingestion

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Equation for calculating gastric volume in patients with previous gastric sleeve
Time Frame: through study completion, an average of one year
Should the existing model prove to be inaccurate, LASSO regression will be performed to identify a more accurate model in this population based on comparing the known volumes of water ingested and the measured cross sectional gastric area.
through study completion, an average of one year
Gastric emptying time
Time Frame: 2 hours after ingestion
The thirty-minute interval scans following ingestion will be used to determine the approximate time at which each patient is able to fully empty the volume of water they have ingested.
2 hours after ingestion

Collaborators and Investigators

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

Sponsor

University of North Carolina, Chapel Hill

Investigators

  • Principal Investigator: Alexander Doyal, MD, MPH, FASA, University of North Carolina, Chapel Hill

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 (Actual)

August 2, 2024

Primary Completion (Actual)

November 15, 2024

Study Completion (Actual)

November 15, 2024

Study Registration Dates

First Submitted

July 23, 2024

First Submitted That Met QC Criteria

July 29, 2024

First Posted (Actual)

August 1, 2024

Study Record Updates

Last Update Posted (Actual)

March 25, 2025

Last Update Submitted That Met QC Criteria

February 21, 2025

Last Verified

July 1, 2024

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • 24-1278

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Deidentified individual data that supports the results will be shared beginning 9 to 36 months following publication provided the investigator who proposes to use the data has approval from an Institutional Review Board (IRB), Independent Ethics Committee (IEC), or Research Ethics Board (REB), as applicable, and executes a data use/sharing agreement with UNC.

IPD Sharing Time Frame

The data will become available 9 to 36 months following publication and will be available indefinitely.

IPD Sharing Access Criteria

The investigator who proposes to use the data must have approval from an Institutional Review Board (IRB), Independent Ethics Committee (IEC), or Research Ethics Board (REB), as applicable, and execute a data use/sharing agreement with UNC.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

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.

Clinical Trials on Aspiration

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Belarus

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

Subscribe