Estimation of P0.1 Using Ultrasound Indexes of Diaphragm Function (PoccUS)

Estimation of Airway Occlusion Pressure at 100 ms Using Ultrasound Indexes of Diaphragm Function

Occlusion pressure at 100 ms (P0.1) is a reliable and non-invasive index of inspiratory drive that can be measured easily on most ventilator. Unfortunately, P0.1 cannot be measured reliably in non-intubated patients. In those receiving non-invasive ventilation, the measurement of P0.1 might be inaccurate due to leaks. P0.1 cannot be measured at all in patients receiving high-flow nasal canulae (HFNC).

Ultrasound indices of diaphragm contractile function, namely diaphragm excursion, velocity and thickening fraction, could be reliable and non-invasive proxies of respiratory drive in non-intubated patient.

Our hypothesis is that ultrasound indices of diaphragm function may reliably estimate P0.1. To validate this hypothesis, theses indices will be measured simultaneously with P0.1 in intubated patients, during diaphragm loading conditions similar to spontaneous breathing: the spontaneous breathing trial (SBT). The SBT is used to evaluate if patients can breathe without the assistance provided by the ventilator, and thus, be weaned from mechanical ventilation.

Study Overview

• Status: Not yet recruiting
• Conditions: Acute Respiratory Disease
• Intervention / Treatment: Device: Spontaneous breathing trial

• Study Type: Observational
• Enrollment (Estimated): 40

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Non-Probability Sample

Study Population

Patients admitted to the intensive care unit who are intubated or have undergone a tracheostomy.

Description

Inclusion Criteria:

• - Age ≥ 18 years old
• Patient intubated or tracheostomized
• Decision by the clinician in charge to initiate a SBT
• After information, the patient or next of kind did not refuse to participate (according to the French law, written informed consent is waived)

Exclusion Criteria:

• - Suspicion of diaphragmatic nerves injury
• Preexisting neuromuscular disease
• Spinal cord injury above C5
• Neuromuscular blockade within last 24 hours
• Body mass index > 40 kg/m2
• Pregnancy or breast feeding
• Patient under legal protection

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
P0.1 and Peak contraction velocity 5 minutes after the initiation of the SBT	Airway occlusion pressure measured 100 ms after the initiation of the inspiration, compared to peak contraction velocity of the diaphragm, measured by subcostal ultrasound in TDI-mode	5 minutes after the initiation of the SBT

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
P0.1 and EXdi	Airway occlusion pressure measured 100 ms after the initiation of the inspiration, compared to maximal excursion of the diaphragm, measured by subcostal ultrasound in M-mode	Immediately after the initiation of the SBT then 5, 10, 15, 20, 25 and 30 minutes after the initiation of the SBT
P0.1 and Peak contraction velocity	Airway occlusion pressure measured 100 ms after the initiation of the inspiration, compared to peak contraction velocity of the diaphragm, measured by subcostal ultrasound in TDI-mode	Immediately after the initiation of the SBT then 10, 15, 20, 25 and 30 minutes after the initiation of the SBT
P0.1 and EXdi,0.1	Airway occlusion pressure measured 100 ms after the initiation of the inspiration, compared to excursion of the diaphragm measured 100 ms after the beginning of the inspiration, measured by subcostal ultrasound in M-mode	Immediately after the initiation of the SBT then 10, 15, 20, 25 and 30 minutes after the initiation of the SBT
P0.1 and Velocity Time Integral	Airway occlusion pressure measured 100 ms after the initiation of the inspiration, compared to velocity time integral of the diaphragm, measured by subcostal ultrasound in TDI-mode	Immediately after the initiation of the SBT then 10, 15, 20, 25 and 30 minutes after the initiation of the SBT
P0.1 and Peak relaxation velocity	Airway occlusion pressure measured 100 ms after the initiation of the inspiration, compared to peak relaxation velocity of the diaphragm, measured by subcostal ultrasound in TDI-mode	Immediately after the initiation of the SBT then 10, 15, 20, 25 and 30 minutes after the initiation of the SBT
P0.1 and Peak relaxation rate	Airway occlusion pressure measured 100 ms after the initiation of the inspiration, compared to peak relaxation rate of the diaphragm, measured by subcostal ultrasound in TDI-mode	Immediately after the initiation of the SBT then 10, 15, 20, 25 and 30 minutes after the initiation of the SBT
P0.1 and TFdi	Airway occlusion pressure measured 100 ms after the initiation of the inspiration, compared to thickening fraction of the diaphragm, measured by intercostal ultrasound in M-mode.	Immediately after the initiation of the SBT then 10, 15, 20, 25 and 30 minutes after the initiation of the SBT
P0.1 and mean thickening velocity	Airway occlusion pressure measured 100 ms after the initiation of the inspiration, compared to mean thickening velocity of the diaphragm, measured by intercostal ultrasound in M-mode.	Immediately after the initiation of the SBT then 10, 15, 20, 25 and 30 minutes after the initiation of the SBT

Collaborators and Investigators

• Sponsor: Assistance Publique - Hôpitaux de Paris

Study record dates

Study Major Dates

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

Study Registration Dates

• First Submitted: April 27, 2026
• First Submitted That Met QC Criteria: April 27, 2026
• First Posted (Actual): May 4, 2026

Study Record Updates

• Last Update Posted (Actual): August 25, 2026
• Last Update Submitted That Met QC Criteria: August 24, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Diaphragm; acute respiratory failure; respiratory drive; Airway occlusion pressure; P0.1; ultrasonography doppler
• Other Study ID Numbers: APHP260589

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

IPD Plan Description

The procedures carried out with the French data privacy authority (CNIL, Commission nationale de l'informatique et des libertés) do not provide for the transmission of the database, nor do the information and consent documents signed by the patients.

Consultation by the editorial board or interested researchers of individual participant data that underlie the results reported in the article after deidentification may nevertheless be considered, subject to prior determination of the terms and conditions of such consultation and in respect for compliance with the applicable regulations.

• IPD Sharing Time Frame: Beginning 3 months and ending 3 years following article publication. Requests out of these time frame can also be submitted to the sponsor
• IPD Sharing Access Criteria: Researchers who provide a methodologically sound proposal.
• 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