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.

NCT Number	NCT06996665
Lead Sponsor	Sir Run Run Shaw Hospital
Conditions	Respiratory Failure
Enrollment	100 participants
Start Date	2025-06-01
Primary Completion	2025-12-30 (estimated)
Study Completion	2026-12-02 (estimated)
Updated on ClinicalTrials.gov	2026-03-25