DiaphragmSNIFF IINCT03129386
Defining the Normal Range for Maximal Sniff Diaphragm Thickening Fraction
An observational study of Diaphragm, run by University Health Network, Toronto at 1 site in Canada.
Trial summary
This study is investigating the normal range of maximal diaphragm thickness during a sniff inspiratory manoeuvre using ultrasound in healthy subjects stratified by age and gender. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Diaphragm
- How many people
- 60 participants
- Where
- 1 siteCanada
- Study dates
- 8 Jun 2016to Jan 2019
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: Healthy adult subjects with no antecedent history of neuromuscular or cardiorespiratory disease.
Who may be able to join
- Over 18 years of age
Who cannot join
- Antecedent history of neuromuscular or cardiorespiratory disease
Trial locations and contacts
1 site in 1 country.
About this study
This study is investigating the normal range of maximal diaphragm thickness during a sniff inspiratory manoeuvre using ultrasound in healthy subjects stratified by age and gender.
Read the detailed description
Diaphragm dysfunction is associated with poor clinical outcomes in critically ill patients but is difficult to diagnose. Traditionally, diaphragm function is measured by evaluating inspiratory muscle strength via maximal inspiratory pressure (MIP). However, this technique relies on a volitional maximal effort and can be challenging for patients to perform.
An alternative to measuring inspiratory muscle strength is the sniff inspiratory pressure approach. During short, sharp sniffs, the diaphragm is maximally activated.
Currently, there are no reported values of the normal range of maximal diaphragm thickness during a sniff maneuver. This study will define the normal range of values for sniff maximal diaphragm thickening fraction, maximal thickening against an occluded airway, and diaphragm thickening during resting tidal breathing in healthy subjects.
- Conditions
- Diaphragm
What is being measured
The primary outcome is the main question the study is designed to answer.
Sniff diaphragm thickening fraction
Thickening of the diaphragm during an inspiratory sniff
Measured: Day 1
Maximal diaphragm thickening fraction
Thickening of the diaphragm during a maximal inspiratory effort
Measured: Day 1
Resting tidal thickening fraction
Thickening of the diaphragm during resting tidal breathing
Measured: Day 1
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted26 Apr 2017
- Study start8 Jun 2016
- Primary completionDec 2018
- Study completionJan 2019
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for DiaphragmStudies of the same condition, open and under way.
- More trials run by University Health Network, TorontoThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 60 participants (actual)
Sponsor and investigators
- Lead sponsor
- University Health Network, Toronto
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Ewan C Goligher, MD, PhD, Principal investigator, University Health Network, Toronto
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03129386
- Sponsor's protocol ID
- 15-8998
- Acronym
- SNIFF II
- Status last verified
- Apr 2019
- First submitted
- 4 Apr 2017
- Last updated
- 23 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Currently, there is no plan to make data IPD available to others.
Study at a glance
From the registry record, last updated by the sponsor on 23 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Defining the Normal Range for Maximal Sniff Diaphragm Thickening Fraction
- ClinicalTrials.gov ID
- NCT03129386
- Acronym / sponsor ID
- SNIFF II / 15-8998
- Conditions
- Diaphragm
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 60 participants (actual)
- Lead sponsor
- University Health Network, TorontoUniversity, hospital or other
- Study start
- 8 Jun 2016 (actual)
- Primary completion
- Dec 2018 (actual)
- Study completion
- Jan 2019 (actual)
- First posted
- 26 Apr 2017 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study is investigating the normal range of maximal diaphragm thickness during a sniff inspiratory manoeuvre using ultrasound in healthy subjects stratified by age and gender.
Detailed description
Diaphragm dysfunction is associated with poor clinical outcomes in critically ill patients but is difficult to diagnose. Traditionally, diaphragm function is measured by evaluating inspiratory muscle strength via maximal inspiratory pressure (MIP). However, this technique relies on a volitional maximal effort and can be challenging for patients to perform.
An alternative to measuring inspiratory muscle strength is the sniff inspiratory pressure approach. During short, sharp sniffs, the diaphragm is maximally activated.
Currently, there are no reported values of the normal range of maximal diaphragm thickness during a sniff maneuver. This study will define the normal range of values for sniff maximal diaphragm thickening fraction, maximal thickening against an occluded airway, and diaphragm thickening during resting tidal breathing in healthy subjects.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- Healthy adult subjects with no antecedent history of neuromuscular or cardiorespiratory disease.
Key inclusion criteria (1 listed)
- Over 18 years of age
Key exclusion criteria (1 listed)
- Antecedent history of neuromuscular or cardiorespiratory disease
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Sniff diaphragm thickening fraction
Time frame: Day 1
Thickening of the diaphragm during an inspiratory sniff
Maximal diaphragm thickening fraction
Time frame: Day 1
Thickening of the diaphragm during a maximal inspiratory effort
Resting tidal thickening fraction
Time frame: Day 1
Thickening of the diaphragm during resting tidal breathing
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 23 Jun 2026.
- Individual participant dataSharing planned: No. Currently, there is no plan to make data IPD available to others.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Ewan C Goligher, MD, PhD principal investigator
University Health Network, Toronto
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Diaphragm, run by University Health Network, Toronto at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 23 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Sniff diaphragm thickening fraction (time frame: Day 1). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 23 Jun 2026.