INSPIRatory Efforts Estimation Under High-flow Nasal Oxygen (INSPIRE-Pilot)

INSPIRatory Efforts Estimation Under High-flow Nasal Oxygen: a Pilot Study

High-flow nasal oxygen (HFNO) is recommended as first-line treatment to prevent intubation in acute hypoxemic respiratory failure and to prevent reintubation after extubation. Accumulating data suggest that strong inspiratory efforts and their persistence are associated with HFNO failure. However, tools to monitor continuously and noninvasively inspiratory efforts are lacking. The investigators have developed an algorithm estimating noninvasively inspiratory efforts under HFNO. This pilot study aims at testing the feasibility of estimating inspiratory efforts in patients treated with HNFO.

Study Overview

• Status: Completed
• Conditions: Respiratory Insufficiency; Dyspnea; Work of Breathing; Oxygen
• Intervention / Treatment: Other: Non-invasive estimation of inspiratory effort

Detailed Description

High-flow nasal oxygen (HFNO) is recommended as first-line treatment to prevent intubation in acute hypoxemic respiratory failure and to prevent reintubation after extubation (alone in patients at low-risk of extubation failure, alternating with noninvasive ventilation in patients at high-risk of extubation failure). It consists in delivering high flow of heated and humidified gas enriched with oxygen through nasal cannulas. However, HFNO failure occurs in 30 to 50% of cases in acute hypoxemic respiratory failure and 10 to 20% of cases after extubation.

Accumulating data suggest that strong inspiratory efforts and their persistence are associated with HFNO failure. However, the monitoring of inspiratory efforts is challenging, especially in patients breathing spontaneously through the nose under HFNO. On a bench study, the investigators have developed an algorithm estimating noninvasively inspiratory efforts under HFNO based on the analysis of tracings of pressure and flow delivered by the HFNO device using an extracorporeal sensor. The coefficient of determination of the algorithm was high (R2=0.92). This pilot study aims at testing the feasibility of estimating inspiratory efforts in patients treated with HNFO.

• Study Type: Interventional
• Enrollment (Actual): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• France
  • Poitiers, France
    • Poitiers University Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patient ≥ 18 yo admitted to the intensive care unit
• Treated with HFNO for less than 24h to prevent intubation of reintubation
• Affiliated to social insurance
• Consent to participate in the study

Exclusion Criteria:

• Do-not-intubate order at inclusion
• Already included in the study
• Under legal protection

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Critically ill patients treated with HFNO; Patients treated with HFNO for less than 24 hours in ICU

Other: Non-invasive estimation of inspiratory effort; As soon as possible after inclusion and 2 hours later, tracings of pressure and flow delivered by the HFNO device will be collected using a noninvasive extracorporeal sensor placed between the nasal cannulas and the HFNO device, as well as vital signs and dyspnea. At each visit, tracings will be collected for 10 minutes using the HFNO flow set by the clinician and for 10 minutes using an HFNO flow of 30 L/min allowing the patient breathing mouth closed. During the recordings, patients will be monitored closely at the bedside by the investigator. Estimated inspiratory efforts under HFNO will be calculated a posteriori. HFNO failure (intubation or reintubation) will be assessed at day 7 of inclusion. Vital status will be assessed at day 28 of inclusion.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The detection of estimated inspiratory efforts under HFNO in patients breathing through the nose at a flow rate of 30 L/min in at least 16 of the 20 (≥ 80%) patients included.	Inspiratory efforts will be calculated a posteriori using the algorithm developed on the bench, based on the pressure and flow signals delivered by the HFNO device collected during the first recording.	Day 1

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Inspiratory efforts estimated under HFNO in patients breathing through the nose at a flow rate of 30 L/min between HFNO success and failure in the overall population and in each subgroup (prevention of intubation and of reintubation)	Inspiratory efforts estimated under HFNO in patients breathing through the nose at a flow rate of 30 L/min will be calculated a posteriori using the algorithm developed on the bench based on the pressure and flow signals delivered by the HFNO device collected during the first recording. HFNO failure is defined as intubation or reintubation or death at day 7 after inclusion.	Day 7
Inspiratory efforts estimated under HFNO in patients breathing through the nose at a flow rate of 30 L/min between survivors and non survivors at day 28 in the overall population and in each subgroup (prevention of intubation and of reintubation)	Inspiratory efforts estimated under HFNO in patients breathing through the nose at a flow rate of 30 L/min will be calculated a posteriori using the algorithm developed on the bench, based on the pressure and flow signals delivered by the HFNO device collected during the first recording.	Day 28
Inspiratory efforts estimated under HFNO according to dyspnea at each visit	Inspiratory effort estimated under HFNO in patients breathing through the nose at a flow rate of 30 L/min at each recording, and dyspnea score. Dyspnea is defined as a value ≥ 4/10 on a numerical rating scale.	Day 1
The change in inspiratory efforts between the 2 visits between HFNO success and failure in the overall population and in each subgroup (prevention of intubation and of reintubation)	The change in inspiratory efforts is defined as the decrease in estimated inspiratory efforts under HFNO in patients breathing through the nose at a flow rate of 30 L/min calculated a posteriori using the algorithm developed on the bench based on the pressure and flow signals delivered by the HFNO device between the first and second recording. HFNO failure is defined as intubation or reintubation or death at day 7 after inclusion.	Day 7
The change in inspiratory efforts between the 2 visits between survivors and non survivors at day 28 in the overall population and in each subgroup (prevention of intubation and of reintubation)	The change in inspiratory efforts is defined as the decrease in estimated inspiratory efforts under HFNO in patients breathing through the nose at a flow rate of 30 L/min calculated a posteriori using the algorithm developed on the bench based on the pressure and flow signals delivered by the HFNO device between the first and second recording.	Day 28

Collaborators and Investigators

• Sponsor: Poitiers University Hospital
• Investigators: Study Chair: Céline ABONNEAU, Poitiers University Hospital

Study record dates

Study Major Dates

• Study Start (Actual): November 29, 2025
• Primary Completion (Actual): March 13, 2026
• Study Completion (Actual): April 9, 2026

Study Registration Dates

• First Submitted: September 17, 2025
• First Submitted That Met QC Criteria: November 13, 2025
• First Posted (Actual): November 14, 2025

Study Record Updates

• Last Update Posted (Actual): May 22, 2026
• Last Update Submitted That Met QC Criteria: May 21, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: respiratory failure; dyspnea; high-flow nasal oxygen; inspiratory efforts
• Additional Relevant MeSH Terms: Respiratory Tract Diseases; Respiration Disorders; Signs and Symptoms, Respiratory; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Respiratory Insufficiency; Dyspnea
• Other Study ID Numbers: 2025-A01663-46

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: This pilot study will be followed by a larger prospective observational study.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No