DIAPHRAGM STRENGTH AND LUNG VOLUMES

NCT07206459 | Active Not Recruiting

• 1 other identifier: 24-170
• Study Type: observational
• Target: 30
• Locations: 1 country
• Sites: 1

Brief Summary

Diaphragm dysfunction (loss of diaphragm strength) is common in the intensive care unit (ICU) patients using ventilators. The diaphragm is the main muscle of respiration and its dysfunction can prolong mechanical ventilation and increase mortality risk. The ventilator settings determine how much air and pressure the patient gets every breath and how much air is left on the lungs after they breathe out. The amount of air left on the lungs influence diaphragm strength measurements which can affect clinical decisions, such as weaning patients off ventilators. This research aims to explore the relationship between the amount of air left in the lungs and diaphragm strength to create a method of correcting measurements of diaphragm strength according to how much air the patients have in the lungs after they breath out. The investigators will test healthy individuals to understand this relationship, then verify if it holds true for ventilated patients by comparing results from both groups.

Conditions

Mechanical Ventilation

Outcome Measures

Primary Outcomes (1)

• Change in diaphragm strength

  Change in the pressure generated by the diaphragm (cmH₂O), assessed during end-expiratory occlusion on mechanical ventilation while applying phrenic nerve stimulation. Measurement will be obtained repeatedly on Day 1, between 3-5 minutes after each PEEP adjustment.

  Day 1 (within 5 minutes at each PEEP level during the intervention)

Study Arms (2)

Healthy Adults

Healthy participants will be recruited by work of mouth from the Grand Toronto Area. Inclusion criteria for the healthy participants will be age ≥18 years, no acute or chronic condition impacting respiratory, musculoskeletal or neurological system or that would interfere with the performance of the tests; body mass index \<35 kg/m2 and sufficient English fluency to provide informed consent and to follow the study protocols. Exclusion criteria for the healthy participants will be contraindication for PNS (e.g., cardiac pacemaker or implanted defibrillator, cervical implants), contraindication for a nasogastric tube (e.g., esophageal varices, recent nasal bleeding)and pregnancy.

Other: Healthy Patients

Critical Care Patients

Adult patients admitted to St. Michael's Hospital ICU, Unity Health Toronto, Ontario, Canada, Inclusion criteria for patients will be intubation for more than 6 hours, triggering or not the ventilator (any mode of ventilation). Exclusion criteria for patients will be primary contraindication for magnetic PNS, severe neurological disorders, pregnancy, current use of continuous neuromuscular blocking agents at the time of the study procedure, P/F ratio \<120, unstable hemodynamics (2 vasopressors), monitored ICP.

Other: Critically Care Patients

Interventions

Healthy Patients OTHER

RESEARCH DESIGN AND METHODS This will be a physiological observational study Study design. Participants will breathe on CPAP with a ventilator. The investigators will deliver the PNS at PEEP levels of zero cmH2O (baseline EELV), zero cmH2O + an abdominal binder (to reduce lung volume), five cmH2O and ten cmH2O. The abdominal binder will be used to achieve an EELV lower than at baseline. At the end of the protocol another PNS at zero cmH2O (baseline EELV) will be performed. Healthy participants will be exposed to the different levels of PEEP from 2 to 5 minutes before each PNS is performed. At every PEEP level, relative changes in EELV (∆z) will be measured with Electrical Impedance Tomography (EIT) to record relative changes in EELV and the electrical activity of the costal diaphragm will be measured using surface electromyography

Healthy Adults

Critically Care Patients OTHER

RESEARCH DESIGN AND METHODS This will be a physiological observational study Study design. For patients. The investigators will perform PNS at the patients own mode of ventilation at their clinical level of PEEP (baseline EELV), PEEP of zero cmH2O (if acceptable for 5 minutes), clinical PEEP ± 2 - 4 cmH2O. At the end of the protocol, another stimulation at the clinical level of PEEP (baseline EELV) will be performed. Patients will be exposed to the different levels of PEEP from 2 to 5 minutes before each PNS is performed.

Critical Care Patients

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

15 healthy adults and 15 critically ill adult patients admitted to St. Michael's Hospital ICU, Unity Health Toronto, Ontario, Canada. Healthy participants will be recruited by work of mouth from the Grand Toronto Area.

Sponsors & Collaborators

• Unity Health Toronto: lead

Study Sites (1)

St. Michael's Hospital

Toronto, Ontario, Canada

Location

Study Officials

• Laurent Brochard, MD, PhD

  Unity Health Toronto - St. Michael's Hospital

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: OTHER
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: September 15, 2025
• First Posted: October 3, 2025
• Study Start: December 1, 2024
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): December 1, 2026
• Last Updated: October 3, 2025

Record last verified: 2024-11

Data Sharing

• IPD Sharing: Will not share

Locations

CA (1)