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NCT Number: NCT06996665

Diaphragmatic Physiology Similarity Index May Titrate HFNC Flow Setting: A Prospective Observational Study

Study Objective This prospective observational study aims to investigate the role of the Diaphragmatic Physiology Similarity Index (DPSI) derived from speckle tracking ultrasound in titrating high-flow nasal cannula (HFNC) flow settings, and to evaluate its application in patients with acute respiratory failure.

Primary Research Questions

To characterize the features of the DPSI in healthy individuals and in patients with acute respiratory failure.

To assess the behavior of the DPSI under different HFNC flow settings in patients with acute respiratory failure.

Secondary Research Questions

Feasibility and inter-operator reproducibility of diaphragmatic speckle tracking.

Assessment of the Diaphragmatic Contraction Synchrony Index.

Evaluation of End-Diaphragmatic Residual Contraction (EDRC).

Additional fundamental parameters, including diaphragmatic displacement velocity and maximum displacement.

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Key information

Conditions

Respiratory Failure Respiration Disorders Respiratory Insufficiency Respiratory Tract Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China

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Who can participate

Healthy volunteers accepted: Yes

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

Feasibility and reproducibility：adult ICU patients

Methodology for diaphragmatic motion synchrony:healthy adults and adult ICU patients Between-group comparisons and flow-titration study

Inclusion criteria

  • Age ≥18 years old.
  • Clear diagnosis of respiratory failure requiring respiratory support.
  • Expected duration of respiratory support ≥24 hours or (high-flow/non-invasive ventilation) ≥48 hours.
  • Voluntary participation in this study and signed informed consent. If the participant is unable to read or sign the informed consent form due to incapacity (e.g., unconsciousness), the legal guardian must act as a proxy in the informed consent process and sign the form. If the participant cannot read the consent form (e.g., illiterate participants), a witness must observe the informed consent process and sign the form.

Exclusion criteria

  • Severe chest wall deformities or diaphragmatic paralysis.
  • End-stage disease with a predicted life expectancy of less than 24 hours.
  • Inability to acquire STE (strains and echoes) images (e.g., severe subcutaneous emphysema, position limitations).
  • Vulnerable groups other than critically ill patients/elderly/illiterate individuals, including those with mental disorders, cognitive impairments, pregnant women, etc.

Treatment and study plan

High-flow adjustment sequence

Other

Delivers heated, humidified blended oxygen via HFNC with real-time titration based on diaphragmatic speckle-tracking metrics (e.g., DPSI, contraction synchrony). Flow is adjusted in predefined increments to reach target diaphragmatic physiology while FiO₂ is titrated to maintain target SpO₂. Ultrasound feedback is used for bedside decisions; safety triggers allow clinical override.

Primary outcomes

  1. Diaphragmatic Physiology Similarity Index (DPSI)

    Time frame: Healthy Participants: Baseline； Baseline evaluation at the time of enrollment change with each change in ventilation parameters.

    The objective of this prospective observational study is to explore the Diaphragmatic Physiology Similarity Index (DPSI), derived from speckle tracking ultrasound, in guiding the adjustment of high-flow nasal cannula (HFNC) flow settings, and to assess its application in patients with acute respiratory failure.

Secondary outcomes

  1. Adverse events including pneumothorax, hemodynamic instability, and other complications

    Time frame: At baseline (upon enrollment), 1 hour / 6 hours / 24 hours after intervention, and during daily morning assessments until extubation or day 28.

  2. Arterial blood gas analysis (ABG analysis)

    Time frame: At baseline (upon enrollment), 1 hour / 6 hours / 24 hours after intervention, and during daily morning assessments until extubation or day 28.

  3. Diaphragmatic Contraction Synchrony Index

    Time frame: After each HFNC flow adjustment: Measure contraction synchrony during each flow setting period.

    Evaluate the diaphragmatic contraction synchrony index, assessing the degree to which the diaphragm contracts as a coordinated unit.

  4. ICC (Intraclass Correlation Coefficient)

    Time frame: At each ultrasound assessment, record the percentage of analyzable images. Compare measurements at the beginning and throughout the study among operators.

    Evaluate the feasibility and inter-operator reproducibility of diaphragmatic speckle tracking ultrasound.

  5. Evaluation of End-Diaphragmatic Residual Contraction (EDRC)

    Time frame: After each mechanical ventilation period: Measure EDRC at the end of the mechanical ventilation phase, noting the diaphragm's ability to recover.

    Assess the residual contraction of the diaphragm after mechanical ventilation to understand its recovery ability.

  6. Diaphragmatic Displacement Velocity and Maximum Displacement

    Time frame: At each flow setting change: Measure the diaphragm's displacement velocity and maximum displacement at each HFNC flow rate adjustment.

    Displacement Velocity: The speed at which the diaphragm moves during each breath cycle.

    Maximum Displacement: The maximum distance the diaphragm moves during inhalation and exhalation.

  7. Diaphragmatic ultrasound parameters (maximum displacement, thickening fraction, etc.)

    Time frame: At baseline (upon enrollment), 1 hour / 6 hours / 24 hours after the intervention, and daily morning assessments until extubation or day 28.

Study contacts

Contact information is provided by the study sponsor or research team.

Huiqing Ge

CONTACT

[email protected]

+86 13588706787 ext. 3588706787

Yiqing Xu

CONTACT

[email protected]

+86 13634115344

Sponsors and collaborators

Lead sponsor

Sir Run Run Shaw Hospital

Other

Registry information

Important dates

Study start
2025
Primary completion
2025
Study completion
2026
First posted
May 30, 2025
Registry last updated
Mar 25, 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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