The Geniohyoid Muscle in Critical Illness

Assessing the Feasibility and Reliability of an Ultrasound-based Method of Measuring the Geniohyoid Muscle in Mechanically Ventilated Patients - an Observational Study

We know that many patients lose muscle due to being unwell in an intensive care unit. This muscle loss can lead to weakness of the arms and legs when they leave the unit, and when they go home. For many years we have measured the size of these arm and leg muscles using an ultrasound machine, to take a picture of the muscles.

We also know that patients who are on a ventilator (or "breathing machine") often have problems swallowing when the breathing tube is removed from their mouth. We think that this is because the muscles of swallowing may also shrink. One of these muscles sits under the jaw and can be measured with ultrasound - the method has been shown to be accurate and reliable in awake volunteers, but these volunteers are usually sat upright in a chair with their mouth closed.

Before we can measure whether these muscles get smaller, we need to assess whether the method we have chosen is suitable in patients on a ventilator; these patients are lying in bed, and their mouths are open slightly due to the breathing tube.

Proposed Method

We would like to measure the size of a muscle under the jaw (called the geniohyoid muscle) in patients who are sedated and have a breathing tube in their mouth connected to a ventilator.

Using a normal hospital ultrasound machine, one researcher will place the ultrasound probe under the patient's jaw. When they are happy the probe is in the right place, they will take a picture of the muscle and measure its size and thickness. After a short break, the researcher will repeat this process. After a second short break, another researcher who did not watch the first researcher will also place the probe under the jaw and take a picture of the muscle.

We can then use these measurements to answer the following questions:

1. How many patients scanned produced images that could be measured?
2. How consistent are the measurements if one person measures the same muscle twice?
3. If two people measure the same muscle, do their measurements agree with each other?

The patients will be under sedation when they take part in the study. Because of this, they cannot consent to take part in the study. We would ask the patient's next of kin or carer to advise on whether the patient would want to take part. When the patient is awake and has the breathing tube removed, we would ask them to sign a consent form to use their data.

Study Overview

• Status: Not yet recruiting
• Conditions: Mechanical Ventilation

Detailed Description

Introduction

Many patients who are mechanically ventilated due to critical illness have difficulty in swallowing after the endotracheal tube is removed, a phenomenon known as Post Extubation Dsyphagia (PED). Although multifactorial, atrophy of the swallowing muscles is a potential cause.

Ultrasound is a commonly used investigative modality for the measurement of muscles in critically unwell patients. Measurements can be performed repeatedly over time to track changes in muscle size during the course of a patient's admission. In critically unwell patients, much of the research is focussed on muscles of the limbs and trunk. The muscles of swallowing have been measured using ultrasound, but in awake patients adopting an optimal seated position. Critically unwell patients are bedbound, and the endotracheal tube leaves their mouth in an open position. Before embarking on a study using ultrasound to attempt to track changes in muscle size in the muscles of swallowing, we first wish to assess if such a method is both feasible and reliable.

Methods

Critically unwell patients who are sedated and mechanically ventilated will be recruited into the study after discussion with a patient's personal consultee. The geniohyoid (GH) muscle will be scanned in both the coronal and sagittal planes. The patient will be scanned three times. Twice by one assessor, and once by a second assessor. Cross sectional areas (CSA) of GH will be measured at a later time using image processing software (ImageJ, NIH, USA). Echogenicity, a measurement of the brightness of muscle on ultrasound, will also be assessed.

Results

The primary outcome is to obtain the proportion of patients whose images from ultrasound can provide satisfactory measurement data, in each plane. Furthermore, we will assess the repeatability of each measurement by calculating the intra-rater agreement, and the inter-rater agreement to assess agreement between assessors. An estimate of the mean CSA in each plane will be calculated.

Conclusions

This preliminary data will give us an estimate of the proportion of patients who can provide satisfactory images of GH, in preparation for a larger study assessing longitudinal changes in CSA. Further, the study will give data on both the inter- and intra-rather agreement of the method.

• Study Type: Observational
• Enrollment (Estimated): 30

Contacts and Locations

Study Locations

• United Kingdom
  • Warrington, United Kingdom, WA5 1QG
    • Intensive Care Unit
    • Contact: Peter Turton, MBChB (Hons) MPhil FRCA FFICM; Phone Number: 5594 01925 635911; Email: peter.turton1@nhs.net

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Non-Probability Sample

Study Population

Mechanically ventilated patients via an endotracheal tube who are admitted to the Intensive Care Unit of Warrington Hospital (North Cheshire and Mersey NHS Foundation Trust), at any time of their admission.

Description

Inclusion Criteria:

• · Mechanically ventilated patient on the intensive care unit

  • Endotracheal tube via the mouth in-situ (size 7.0 and above)
  • Can be recruited at any time during their admission

Exclusion Criteria:

• · Ventilated via a nasal endotracheal tube

  • Ventilated via a tracheostomy
  • Ventilated via a micro-endotracheal tube
  • Any previous or active history of head and neck cancer
  • Any previous head and neck surgery (excluding tonsillectomy and adenoidectomy)
  • Any cranio-facial deformity that would render access to the jaw difficult, including but not limited to short thymo-mental distance
  • Any neuromuscular disorder, including previous stroke
  • Any previous history of dysphagia or swallowing disorder
  • Pregnant patients
  • Patients under 18 years of age
  • Agitation or movement that would make measurement difficult or inaccurate

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
Mechanically ventilated patient group; Any eligible patient who is being mechanically ventilated in the site's intensive care unit, via an endotracheal tube.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Satisfactory image acquisition of the geniohyoid muscle in the coronal plane (n, proportion)	To obtain an estimate for the proportion of patients in which satisfactory images can be measured, in both measured planes (coronal and sagittal views). An "unsatisfactory" image is due to either the investigator being unable to adequately visualise the GH muscle with the probe (e.g. due to subcutaneous fat, difficult patient positioning, or when an image has been obtained, the offline CSA measurement cannot be performed due to inadequate visualisation of the muscle's fascial border. In addition, the co-efficient of variance of the three images taken must be less than 5%.	Day 1 (patients are only on the day of the ultrasound)
Satisfactory image acquisition of the geniohyoid muscle, sagittal plane (n, proportion)	To obtain an estimate for the proportion of patients in which satisfactory images can be measured, in the sagittal plane. An "unsatisfactory" image is due to either the investigator being unable to adequately visualise the GH muscle with the probe (e.g. due to subcutaneous fat, difficult patient positioning, or when an image has been obtained, the offline CSA measurement cannot be performed due to inadequate visualisation of the muscle's fascial border. In addition, the co-efficient of variance of the three images taken must be less than 5%.	Day 1 - patients are only in the study on the day of the ultrasound scan

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Intra-rater agreement, cross sectional area of geniohyoid muscle, coronal plane	In this outcome, investigator A will take 3 images (set A) of the geniohyoid muscle in the coronal plane. After a short break, a second set of 3 images (set B) will be taken. Intra-rater agreement will be assessed by comparing mean and standard deviation of both set A and B, and calculating the intra-class correlation co-efficient for consistency.	Day 1
Intra-rater agreement, cross sectional area of geniohyoid muscle, sagittal plane	In this outcome, investigator A will take 3 images (set A) of the geniohyoid muscle in the sagittal plane. After a short break, a second set of 3 images (set B) will be taken. Intra-rater agreement will be assessed by comparing mean and standard deviation of both set A and B, and calculating the intra-class correlation co-efficient for consistency.	Day 1
Inter-rater agreement, cross sectional area of geniohyoid muscle, coronal plane	In this outcome, investigator A will take 3 images (set A) of the geniohyoid muscle in the coronal plane. After a short break, investigator B will take a second set of 3 images (set C) Intra-rater agreement will be assessed by comparing mean and standard deviation of both set A and C, and calculating the intra-class correlation co-efficient for agreement.	Day 1
Inter-rater agreement, cross sectional area of geniohyoid muscle, sagittal plane	In this outcome, investigator A will take 3 images (set A) of the geniohyoid muscle in the coronal plane. After a short break, investigator B will take a second set of 3 images (set C) Intra-rater agreement will be assessed by comparing mean and standard deviation of both set A and C, and calculating the intra-class correlation co-efficient for agreement.	Day 1
Intra-rater agreement, echogenicity of the geniohyoid muscle, sagittal plane	Investigator A will have taken 2 sets of 3 images (sets A and B) of the geniohyoid muscle in the sagittal plane. Echogenicity will be measured offline using appropriate imaging software (Image J, NIH) and compared by mean and standard deviation, and by intra-class correlation coefficient for consistency.	Day 1
Inter-rater agreement, echogenicity of the geniohyoid muscle, sagittal plane	Investigator A will have taken 2 sets of 3 images (sets A and B) of the geniohyoid muscle in the sagittal plane, and investigator B will take set of 3 images (set C). Echogenicity will be measured offline using appropriate imaging software (Image J, NIH) and compared by mean and standard deviation, and by intra-class correlation coefficient for absolute agreement.	Day 1

Collaborators and Investigators

• Sponsor: Warrington Hospital

Study record dates

Study Major Dates

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

Study Registration Dates

• First Submitted: May 18, 2026
• First Submitted That Met QC Criteria: May 18, 2026
• First Posted (Actual): May 26, 2026

Study Record Updates

• Last Update Posted (Actual): May 26, 2026
• Last Update Submitted That Met QC Criteria: May 18, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: mechanical ventilation; ultrasound; swallowing; geniohyoid
• Other Study ID Numbers: W0001; 26/NW/0011 (Other Identifier: REC - North West Greater Manchester South)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: All IPD that underlie results in a publication will be made available upon reasonable request.
• IPD Sharing Time Frame: At any point after the cessation of the study.
• IPD Sharing Access Criteria: Anonymised baseline data (age, weight, height etc), and their associated measured (geniohyoid muscle cross sectional areas and echogenicities) and associated results and summary/inferential statistics will be made available on request to the corresponding author of any future publication.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; ICF

Drug and device information, study documents

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