Diaphragm InjurySNIFF IIINCT03129217
The Validity of Maximal Diaphragm Thickening Fraction to Measure Diaphragm Function in Mechanically Ventilated Patients
An observational study of Diaphragm Injury and Weaning Failure, run by University Health Network, Toronto at 1 site in Canada.
Trial summary
This study is designed to determine whether maximal diaphragm thickening fraction measured by ultrasound during volitional maximal inspiratory efforts is a valid measure of diaphragm function in mechanically ventilated patients. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Diaphragm Injury, Weaning Failure, Mechanical Ventilation Complication
- How many people
- 29 participants
- Where
- 1 siteCanada
- Study dates
- Nov 2015to Apr 2020
- 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
- No healthy volunteers
- Adult, Older adult
Study population: Critically ill patients with acute respiratory failure requiring invasive mechanical ventilation who meet readiness-to-wean criteria.
Who may be able to join
- Adult patients (≥ 18 years old) with acute respiratory failure receiving invasive mechanical ventilation via endotracheal tube or tracheostomy
- Patients who meet readiness-to-wean criteria (triggering the ventilator; FiO2 ≤ 50%; PEEP ≤ 8 cm H20; hemodynamic stability)
Who cannot join
- Contraindication to phrenic nerve stimulation (chest tube; cardiac pacemaker or implanted defibrillator; cervical implants; use of neuromuscular blocking agents within the 24 hours preceding the first diaphragm assessment (with the exception of succinylcholine used during rapid-sequence induction of anaesthesia for intubation); cervical spine injury; known pregnancy)
- Patients experiencing an acute exacerbation of an obstructive lung disease (chronic obstructive pulmonary disease (COPD), asthma, bronchiectasis)
Trial locations and contacts
1 site in 1 country.
About this study
This study is designed to determine whether maximal diaphragm thickening fraction measured by ultrasound during volitional maximal inspiratory efforts is a valid measure of diaphragm function in mechanically ventilated patients.
Read the detailed description
Classically, assessing diaphragm function requires direct measurements of transdaphragmatic pressure generation. A critical requirement for valid measurements is a maximal volitional patient effort. An alternative is to standardize the stimulus to the diaphragm using magnetic twitch stimulation fo the phrenic nerve. This is the gold standard technique for diaphragm function measurement in the respiratory physiology laboratory.
Twitch measurements require technical expertise and expensive equipment; this technique is therefore basically limited to the laboratory. Bedside ultrasonography has been proposed as a method for measuring diaphragm function by assessing the thickening of the muscle during a maximal inspiratory effort. In order to achieve a maximal volitional effort in mechanically ventilated patients, several methods may be employed: coached maximal efforts, coached sniffing, and transient airway occlusion to stimulate respiratory drive (Marini maneuver).
The investigators are evaluating the validity of diaphragm functional assessment using bedside ultrasound in combination with coached efforts/sniffing/Marini maneuver against the gold standard technique: twitch transdiaphragmatic pressure.
- Keywords
- Diaphragm function, Acute respiratory failure, Weaning
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Patients weaning from mechanical ventilation | Not described |
What is being measured
The primary outcome is the main question the study is designed to answer.
Maximal diaphragm thickening fraction
Diaphragm ultrasound to measure thickening fraction
Measured: On day of study
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 startNov 2015
- Primary completionApr 2020
- Study completionApr 2020
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Diaphragm InjuryStudies 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
- 29 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
- NCT03129217
- Sponsor's protocol ID
- 15-9644
- Acronym
- SNIFF III
- Status last verified
- Aug 2020
- First submitted
- 5 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 available to other researchers.
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
- The Validity of Maximal Diaphragm Thickening Fraction to Measure Diaphragm Function in Mechanically Ventilated Patients
- ClinicalTrials.gov ID
- NCT03129217
- Acronym / sponsor ID
- SNIFF III / 15-9644
- Keywords
- Diaphragm function, Acute respiratory failure, Weaning
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 29 participants (actual)
- Lead sponsor
- University Health Network, TorontoUniversity, hospital or other
- Study start
- Nov 2015 (actual)
- Primary completion
- Apr 2020 (actual)
- Study completion
- Apr 2020 (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 designed to determine whether maximal diaphragm thickening fraction measured by ultrasound during volitional maximal inspiratory efforts is a valid measure of diaphragm function in mechanically ventilated patients.
Detailed description
Classically, assessing diaphragm function requires direct measurements of transdaphragmatic pressure generation. A critical requirement for valid measurements is a maximal volitional patient effort. An alternative is to standardize the stimulus to the diaphragm using magnetic twitch stimulation fo the phrenic nerve. This is the gold standard technique for diaphragm function measurement in the respiratory physiology laboratory.
Twitch measurements require technical expertise and expensive equipment; this technique is therefore basically limited to the laboratory. Bedside ultrasonography has been proposed as a method for measuring diaphragm function by assessing the thickening of the muscle during a maximal inspiratory effort. In order to achieve a maximal volitional effort in mechanically ventilated patients, several methods may be employed: coached maximal efforts, coached sniffing, and transient airway occlusion to stimulate respiratory drive (Marini maneuver).
The investigators are evaluating the validity of diaphragm functional assessment using bedside ultrasound in combination with coached efforts/sniffing/Marini maneuver against the gold standard technique: twitch transdiaphragmatic pressure.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Patients weaning from mechanical ventilation | – | – |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Critically ill patients with acute respiratory failure requiring invasive mechanical ventilation who meet readiness-to-wean criteria.
Key inclusion criteria (2 listed)
- Adult patients (≥ 18 years old) with acute respiratory failure receiving invasive mechanical ventilation via endotracheal tube or tracheostomy
- Patients who meet readiness-to-wean criteria (triggering the ventilator; FiO2 ≤ 50%; PEEP ≤ 8 cm H20; hemodynamic stability)
Key exclusion criteria (2 listed)
- Contraindication to phrenic nerve stimulation (chest tube; cardiac pacemaker or implanted defibrillator; cervical implants; use of neuromuscular blocking agents within the 24 hours preceding the first diaphragm assessment (with the exception of succinylcholine used during rapid-sequence induction of anaesthesia for intubation); cervical spine injury; known pregnancy)
- Patients experiencing an acute exacerbation of an obstructive lung disease (chronic obstructive pulmonary disease (COPD), asthma, bronchiectasis)
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
Maximal diaphragm thickening fraction
Time frame: On day of study
Diaphragm ultrasound to measure thickening fraction
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 available to other researchers.
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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 Injury and Weaning Failure, 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 2 inclusion and 2 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?
Maximal diaphragm thickening fraction (time frame: On day of study). 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.