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NCT Number: NCT07747532

Reliability of Diaphragm Ultrasound: Intra- and Interrater Analysis

It is often difficult for anesthesiologists to select an ultrasound method that will give consistent results and also be a reliable way to examine the diaphragm, especially on the left side of the chest.

In this study, two anesthesiologists blinded to one another's scan results, will perform ultrasound scan of the diaphragm using three different methods and the measurements will be analyzed to see the reliability of each method.

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Key information

Conditions

Diaphragm Issues

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Toronto Western Hospital, University Health Network

Toronto, Ontario, M5T 2S8, Canada

About this study

Ultrasound assessment of the diaphragm is a portable and non-invasive option for assessing and monitoring diaphragmatic function. The diaphragm is the main muscle used for breathing. It is a muscular organ that lies in between the thorax (chest) and abdomen. By moving up and down, it helps in our breathing by aiding both the right and the left lung to inflate and deflate. Assessing diaphragmatic function provides meaningful information in the setting of chronic lung diseases, obesity and diseases of nerve and muscle dysfunction and in assessing the diaphragmatic function before and after surgery. However, ultrasound assessment of the diaphragm on the left side of chest is sometimes difficult or impossible in a large proportion of patients.

There are currently three ultrasound methods to examine the diaphragm, and to date, it is not clear which technique should be used as the most reliable method. The purpose of this research study is to find out how much reliable the different ultrasound methods are in assessing the movement of the diaphragm during respiration.

In this study, two anesthesiologists blinded to one another's scan results, will perform ultrasound scan of the diaphragm using three different methods and the measurements will be analyzed to see the reliability of each method. The investigators believe that the results of this study can guide medical professionals in selecting an ultrasound method that will give consistent results and a more reliable way to examine the diaphragm, especially on the left side of the chest.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Participants must meet all the following inclusion criteria to be eligible for the study:

  • Any elective surgical patient
  • Age ≥18 years
  • American Society of Anesthesiologists class I to III

Exclusion criteria

Participants will not be eligible for the study if any of the exclusion criteria is present:

  • Pregnancy - patients will be asked if they are pregnant or not and screened post-consent from their medical chart.
  • History of diaphragmatic dysfunction
  • Previous surgical procedures on the lung, thorax or diaphragm.
  • Inability to understand the study activities and provide informed consent when explained about the study and the consent process
  • Refusal to participate in study

Treatment and study plan

Primary outcomes

  1. To measure the intra-rater reliability of the excursion of the zone of apposition, (ZOA)

    Time frame: Through study completion, an average of 2 years

    To measure the intra-rater (between two measurements of the same scanner) reliability of the excursion of the ZOA using a linear probe over the lateral chest wall, quantified by Intraclass correlation coefficients (ICC).

  2. To measure the inter-rater reliability of the excursion of the zone of apposition, (ZOA)

    Time frame: Through study completion, an average of 2 years

    To measure the inter-rater (between two ultrasound scanners) reliability of the excursion of the zone of apposition, (ZOA) using a linear probe over the lateral chest wall, quantified by Intraclass correlation coefficients (ICC).

Secondary outcomes

  1. To measure the intra-rater reliability of the excursion of the dome of the diaphragm (DOD)

    Time frame: Through study completion, an average of 2 years

    To measure the intra-rater (between two measurements of the same scanner) reliability of the excursion of the DOD measured using a curvilinear probe via the subcostal abdominal window, quantified by ICCs

  2. To measure the inter-rater reliability of the excursion of the dome of the diaphragm (DOD)

    Time frame: Through study completion, an average of 2 years

    To measure the inter-rater (between two ultrasound scanners) reliability of the excursion of the DOD measured using a curvilinear probe via the subcostal abdominal window, quantified by ICCs

  3. To measure intra-rater reliability of the Thickening Fraction, (TF) of the ZOA

    Time frame: Through study completion, an average of 2 years

    To measure intra-rater (between two measurements of the same scanner) reliability of the Thickening Fraction, TF of the ZOA measured using a linear probe over the lateral chest wall, quantified by ICCs.

  4. To measure inter-rater reliability of the Thickening Fraction, (TF) of the ZOA

    Time frame: Through study completion, an average of 2 years

    To measure inter-rater (between two ultrasound scanners) reliability of the Thickening Fraction, (TF) of the ZOA measured using a linear probe over the lateral chest wall, quantified by ICCs.

  5. To measure the distribution of diaphragmatic measurements obtained for the ZOA method (Excursion of the ZOA)

    Time frame: Through study completion, an average of 2 years

    To measure the distribution of diaphragmatic measurements obtained for the ZOA method (Excursion of the ZOA) using F-tests for ICCs

  6. To measure the distribution of diaphragmatic measurements obtained for the DOD method

    Time frame: Through study completion, an average of 2 years

    To measure the distribution of diaphragmatic measurements obtained using the DOD method (Excursion of the DOD) using F-tests for ICCs

  7. To measure the distribution of diaphragmatic measurements obtained for the Thickening Fraction method (TF of the ZOA)

    Time frame: Through study completion, an average of 2 years

    To measure the distribution of diaphragmatic measurements obtained for the Thickening fraction method (TF of the ZOA) using F-tests for ICCs

Study contacts

Contact information is provided by the study sponsor or research team.

Jayanta Chowdhury

CONTACT

[email protected]

4166035800 ext. 2016

Laura Giron-Arango, MD

CONTACT

[email protected]

4166035118

Sponsors and collaborators

Lead sponsor

University Health Network, Toronto

Other

Registry information

Acronym: ReDU analysis

Important dates

Study start
2026
Primary completion
2028
Study completion
2028
First posted
Aug 5, 2026
Registry last updated
Aug 5, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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