Using a diaphragm ultrasound index (DPSI) to set high-flow nasal oxygen flow

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

This will test whether a diaphragm ultrasound score (DPSI) can help doctors set the best high-flow nasal cannula (HFNC) flow for adults with acute respiratory failure.

Quick facts

• Phase: Not applicable
• Study type: Interventional
• Enrollment: 100 (estimated)
• Ages: 18 Years and up
• Sex: All
• Sponsor: Sir Run Run Shaw Hospital (Academic / other)
• Locations: 2 sites (Hangzhou, Zhejiang and 1 other locations)
• Trial ID: NCT06996665 on ClinicalTrials.gov

What this trial studies

This is a prospective observational study using speckle-tracking ultrasound to derive a Diaphragmatic Physiology Similarity Index (DPSI) and observe its behavior. The study will characterize DPSI features in healthy volunteers and in adults with acute respiratory failure, and will record DPSI changes across different HFNC flow settings during a standardized high-flow adjustment sequence. Secondary work will measure feasibility, inter-operator reproducibility, diaphragmatic contraction synchrony, end-diaphragmatic residual contraction (EDRC), displacement velocity, and maximum displacement. All imaging and flow adjustments are performed at Sir Run Run Shaw Hospital with ICU patients and healthy adult comparators.

Who should consider this trial

Good fit: Ideal candidates are adults (≥18 years) with a clear diagnosis of acute respiratory failure who require respiratory support (HFNC or noninvasive ventilation) and are expected to need support for at least 24–48 hours.

Not a fit: Patients with severe chest wall deformities, diaphragmatic paralysis, very limited life expectancy (<24 hours), or those unable to obtain adequate diaphragm ultrasound windows are unlikely to benefit from DPSI-guided titration.

Why it matters

Potential benefit: If successful, DPSI-guided HFNC titration could help personalize noninvasive oxygen support, improving breathing comfort and potentially reducing the need for escalation to invasive ventilation.

How similar studies have performed: Prior small studies have shown that diaphragmatic speckle-tracking is feasible and can correlate with diaphragm function, but using a DPSI specifically to titrate HFNC flow is novel and not yet proven.

Eligibility 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.

Where this trial is running

Hangzhou, Zhejiang and 1 other locations

• Sir Run Run shaw Hospital Zhejiang University — Hangzhou, Zhejiang, China (Recruiting)
• Sir Run Run Shaw Hospital, Zhejiang University School of Medicine — Hangzhou, Zhejiang, China (Not_yet_recruiting)

Study contacts

• Study coordinator: Huiqing Ge

Conditions Respiratory Failure; Diaphragm; Speckle Tracking; PEEP