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

Zhejiang University

Status: Enrolling

Conditions: Respiratory Failure

Treatments: Other: High-flow adjustment sequence

Study type: Interventional

Funder types: Other

Identifiers

NCT06996665

20250271

Details and patient eligibility

About

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.

Enrollment: 100 estimated patients

Sex: All

Ages: 18+ years old

Volunteers: Accepts Healthy Volunteers

Inclusion and exclusion criteria

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:

1. Age ≥18 years old.
2. Clear diagnosis of respiratory failure requiring respiratory support.
3. Expected duration of respiratory support ≥24 hours or (high-flow/non-invasive ventilation) ≥48 hours.
4. 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:

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

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Double Blind

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100 participants in 6 patient groups

Feasibility Patient Cohort（No Intervention / Diagnostic Test）

No Intervention group

Description:

Participants undergo an assessment-only diagnostic intervention: diaphragmatic speckle-tracking ultrasound performed at predefined time points during routine care to evaluate feasibility and measurement properties (e.g., foundational speckle-tracking metrics and inter-/intra-operator reproducibility). Images of the bilateral zone of apposition are acquired and analyzed offline for the contraction synchrony index, end-diaphragmatic residual contraction (EDRC), displacement velocity, and maximal displacement. Ultrasound findings are not used for clinical decision-making; respiratory support (e.g., HFNC/ventilator settings) is determined independently by the treating clinicians.

Healthy Volunteer Reference Cohort

No Intervention group

Description:

Healthy volunteers undergo protocolized, assessment-only diaphragmatic speckle-tracking ultrasound to characterize normal diaphragmatic physiology and establish reference ranges; no feasibility or reproducibility endpoints are collected. Bilateral zone-of-apposition images are acquired and analyzed offline for DPSI, contraction synchrony index, end-diaphragmatic residual contraction (EDRC), displacement velocity, and maximal displacement. No therapeutic interventions are delivered, and participation does not alter clinical management.

Sequence 1: 20-30-40-60 L/min

Experimental group

Description:

Participants receive HFNC flows 20→30→40→60 L/min across four periods. Each period maintains the assigned flow for a predefined steady window; FiO₂ is adjusted per routine to meet target SpO₂. At the end of each period, protocolized diaphragmatic speckle-tracking ultrasound (bilateral zone of apposition) is performed with offline analysis of DPSI, contraction synchrony index, EDRC, displacement velocity, and maximal displacement; vital signs, respiratory rate, comfort/tolerance, and oxygenation are recorded. Safety overrides (e.g., hypoxemia, distress, intolerance) permit clinicians to modify or terminate the period.

Treatment:

Other: High-flow adjustment sequence

Sequence 2: 30-60-20-40 L/min

Experimental group

Description:

This sequence administers HFNC flows 30→60→20→40 L/min over four periods. Procedures mirror Sequence 1: predefined steady windows, routine FiO₂ titration, end-of-period speckle-tracking ultrasound with offline metrics (DPSI, synchrony, EDRC, displacement velocity, maximal displacement), and collection of vitals/oxygenation/tolerance; safety triggers allow clinical override.

Treatment:

Other: High-flow adjustment sequence

Sequence 3: 40-20-60-30 L/min

Experimental group

Description:

Participants receive HFNC flows 40→20→60→30 L/min across four periods. A predefined steady window is maintained with routine FiO₂ adjustments. End-of-period speckle-tracking ultrasound is performed with the same offline metrics; vitals, respiratory rate, comfort/tolerance, and oxygenation are captured. Safety triggers enable clinical override.

Treatment:

Other: High-flow adjustment sequence

Sequence 4: 60-40-30-20 L/min

Experimental group

Description:

HFNC flows are delivered 60→40→30→20 L/min over four periods. Each period preserves a steady observation window with routine FiO₂ titration; end-of-period speckle-tracking ultrasound is performed with offline analyses (DPSI, synchrony, EDRC, displacement velocity, maximal displacement), and vitals/oxygenation/tolerance are recorded. Safety overrides may be applied by the treating team.

Treatment:

Other: High-flow adjustment sequence