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NCT Number: NCT07564258

Estimation of P0.1 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.

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Key information

Conditions

Acute Respiratory Disease

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Who can participate

Healthy volunteers accepted: No

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

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

Treatment and study plan

Spontaneous breathing trial

Device

A plateau pressure measurement will be performed before starting the spontaneous breathing trial (SBT). Then, immediately and 5, 10, 15, 20, 25, and 30 minutes after the start of the SBT, the following will be performed as part of the study:

  • Subcostal diaphragmatic ultrasound: M-mode and tissue Doppler
  • Lateral diaphragmatic ultrasound: 2D mode and M-mode
  • Measurement of P0.1
  • Measurement of Pocc during a tele-expiratory pause, only 5 minutes after the start of the SBT.

Primary outcomes

  1. P0.1 and Peak contraction velocity 5 minutes after the initiation of the SBT

    Time frame: 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

Secondary outcomes

  1. P0.1 and EXdi

    Time frame: Immediately after the initiation of the SBT then 5, 10, 15, 20, 25 and 30 minutes after the initiation of the SBT

    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

  2. P0.1 and Peak contraction velocity

    Time frame: Immediately after the initiation of the SBT then 10, 15, 20, 25 and 30 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

  3. P0.1 and EXdi,0.1

    Time frame: Immediately after the initiation of the SBT then 10, 15, 20, 25 and 30 minutes after the initiation of the SBT

    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

  4. P0.1 and Velocity Time Integral

    Time frame: Immediately after the initiation of the SBT then 10, 15, 20, 25 and 30 minutes after the initiation of the SBT

    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

  5. P0.1 and Peak relaxation velocity

    Time frame: Immediately after the initiation of the SBT then 10, 15, 20, 25 and 30 minutes after the initiation of the SBT

    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

  6. P0.1 and Peak relaxation rate

    Time frame: Immediately after the initiation of the SBT then 10, 15, 20, 25 and 30 minutes after the initiation of the SBT

    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

  7. P0.1 and TFdi

    Time frame: Immediately after the initiation of the SBT then 10, 15, 20, 25 and 30 minutes after the initiation of the SBT

    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.

  8. P0.1 and mean thickening velocity

    Time frame: Immediately after the initiation of the SBT then 10, 15, 20, 25 and 30 minutes after the initiation of the SBT

    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.

Sponsors and collaborators

Lead sponsor

Assistance Publique - Hôpitaux de Paris

Other

Registry information

Official study title

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

Acronym: PoccUS

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
May 4, 2026
Registry last updated
Jul 16, 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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