Acute Heart FailurePhase 2/3REDOX-AHFNCT05613218
Oxygen Targets in Acute Heart Failure With Pulmonary Congestion
A Phase 2/3 study testing Oxygen in people with Acute Heart Failure and Pulmonary Congestion, run by Copenhagen University Hospital, Hvidovre at 2 sites in Denmark.
Trial summary
REDOX-AHF compared two oxygen saturation targets in adults admitted with acute heart failure and clinical or radiological signs of congestion. Participants were randomly assigned to a restrictive target of 89-91% or a liberal target of 95-97% for 24 hours. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Acute Heart Failure, Pulmonary Congestion, Hypoxemia
- What is being tested?
- Oxygen
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 135 participants
- Where
- 2 sitesDenmark
- Study dates
- 1 Feb 2024to 3 Mar 2026
- Phase
- Phase 2/3
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Age ≥ 18 years
- Acute (within minutes to days) onset or worsening of subjective dyspnea
- Oxygen saturation <92% (on arterial blood gas) or need of oxygen
- At least one of the following clinical or radiological signs of congestion:
- 1. Pulmonary rales 2. Chest X-ray or CT with pulmonary congestion 3. Lung ultrasound with multiple B-lines
Who cannot join
- More than 4 hours from hospital admission to randomization
- Suspected infection or sepsis
- Known severe pulmonary disease
- Systolic blood pressure <90 mmHg
Trial locations and contacts
2 sites in 1 country.
Denmark2 sites
Bispebjerg Hospital
Copenhagen, 2400
Amager-Hvidovre Hospital
Hvidovre, 2650
About this study
Official title: Restrictive Versus Liberal Oxygenation Targets in Patients With Acute Heart Failure and Pulmonary Congestion - a Randomized Clinical Pilot-trial
REDOX-AHF compared two oxygen saturation targets in adults admitted with acute heart failure and clinical or radiological signs of congestion. Participants were randomly assigned to a restrictive target of 89-91% or a liberal target of 95-97% for 24 hours. An automated oxygen delivery device adjusted oxygen flow while concealing the assigned target from participants and study staff. The main assessment was lung fluid content after 24 hours, measured noninvasively by remote dielectric sensing (ReDS). The trial was conducted at two Danish hospitals. A total of 135 participants were randomized; 134 remained in the modified intention-to-treat population after one participant withdrew consent. The target of 122 participants with complete primary-outcome measurements was reached. Follow-up continued to day 30.
Read the detailed description
Background: One million hospitalizations occur each year with a primary diagnosis of acute heart failure in the USA, with comparable numbers in Europe. Most patients with acute heart failure are treated with supplemental oxygen during hospitalization and guidelines recommend initiation of oxygen therapy if SpO2 <90% (class I, level C). However, no clinical trials of oxygen targets in humans with acute heart failure investigating clinically relevant endpoints have been performed.
Primary objective: To investigate the effect of a restrictive vs. liberal oxygenation-strategy in patients hospitalized with acute heart failure.
Hypothesis: Restrictive oxygenation is associated with improved clinical outcome compared to liberal oxygenation.
Design: Investigator-initiated, prospective, randomized, blinded, multi-center, controlled trial.
Intervention: Patients will be randomized 1:1 in the emergency department to either liberal or restrictive oxygenation after providing informed written consent.
(1) Liberal oxygenation group = SpO2 target of 96%. (2) Restrictive oxygenation group = SpO2 target of 90%.
Patients will have nasal cannula or oxygen mask placed as the usual care, and oxygen is titrated to the prespecified target range. Consented patients will be randomly allocated to study groups via the automated web-based system within REDCap. The allocation will be concealed. Time at randomization will be considered as study time zero (T0). All patients will receive usual standard of care except for their oxygen-administration. The intervention-phase will be 24 h, and hereafter oxygen therapy will be at the discretion of the treating physician.
- Conditions
- Acute Heart Failure, Pulmonary Congestion, Hypoxemia
- Being tested
- Oxygen
- Keywords
- acute heart failure, Pulmonary edema, Oxygen, Pulmonary congestion
- Medical subject headings
- Hypoxia, Pulmonary Edema
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
OxygenDrug
Patients will have nasal cannula or oxygen mask placed as the usual standard of care.
Patients will be screened and randomized in the emergency department to either liberal or restrictive oxygenation after providing informed written consent and oxygen is titrated to the prespecified target range using an automated feedback device (O2MATIC). Consented patients will be randomly allocated to study groups via the web-based system within REDCap. The allocation will be concealed. Time at randomization will be considered as study time zero (T0). All patients will receive usual standard of care except for their O2 management. The intervention will last for 24 h. After 24 h, patients will be switched over to usual care for oxygen therapy. If the treating physician thinks, that the patient need another oxygenation target and it is thought to be harmful to continue with the allocated target, the intervention-phase can be stopped prematurely.
| Study group | Role | What they receive |
|---|---|---|
| Liberal oxygenation group | Active comparator | SpO2 target of 96% Receives: Drug: Oxygen |
| Restrictive oxygenation group | Active comparator | SpO2 target of 90%. Receives: Drug: Oxygen |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in pulmonary parenchymal fluid content from baseline to 24 hours
Change in pulmonary parenchymal fluid content (%) measured noninvasively using remote dielectric sensing (ReDS; Sensible Medical, Netanya, Israel) from baseline to 24 hours. The 24-hour measurement is preceded by 10 minutes without oxygen supplementation. The published protocol specifies ANCOVA with 24-hour ReDS as the outcome and baseline ReDS as a covariate.
Measured: Baseline to 24 hours
Secondary outcomes (4)
Arterial blood gas oxygen concentration (PaO2) at 24 hours
Arterial blood gas oxygen concentration (partial pressure of arterial oxygen, PaO2) measured at 24 hours, preceded by 10 minutes without oxygen supplementation.
Measured: 24 hours
Patient-reported dyspnoea on a 7-point Likert scale at 24 hours
Patient-reported dyspnoea assessed after 24 hours on a 7-point Likert scale ranging from marked worsening to marked improvement.
Measured: 24 hours
Change in respiratory rate from baseline to 24 hours
Change in respiratory rate (breaths per minute) from baseline to 24 hours.
Measured: Baseline to 24 hours
Time to freedom from oxygen-supplementation
Time from randomization to freedom from supplemental oxygen, measured in hours during the index admission, as defined in the manuscript supplement.
Measured: From randomization to oxygen discontinuation during the index admission
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Nov 2022
- Study start1 Feb 2024
- Primary completion2 Feb 2026
- Study completion3 Mar 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Acute Heart FailureStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2/3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- 1:1 allocation
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 135 participants (actual)
Sponsor and investigators
- Lead sponsor
- Copenhagen University Hospital, Hvidovre
- Sponsor type
- University, hospital or other
- Collaborators
- Bispebjerg Hospital
- Responsible party
- Principal investigator, Johannes Grand, Copenhagen University Hospital, Hvidovre
- Investigators
- Jens Hove, MD, PhD, Study chair, Copenhagen University Hospital Amager-Hvidovre Department of CardiologyJohannes Grand, MD, PhD, Principal investigator, Copenhagen University Hospital Amager-Hvidovre Department of CardiologyIda Taraldsen, MD, Study director, Copenhagen University Hospital Amager-Hvidovre Department of Cardiology
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05613218
- Sponsor's protocol ID
- REDOX
- Acronym
- REDOX-AHF
- Status last verified
- Oct 2026
- First submitted
- 4 Nov 2022
- Last updated
- 26 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 26 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Restrictive Versus Liberal Oxygenation Targets in Patients With Acute Heart Failure and Pulmonary Congestion - a Randomized Clinical Pilot-trial
- ClinicalTrials.gov ID
- NCT05613218
- Acronym / sponsor ID
- REDOX-AHF / REDOX
- Conditions
- Acute Heart Failure, Pulmonary Congestion, Hypoxemia
- Keywords
- acute heart failure, Pulmonary edema, Oxygen, Pulmonary congestion
- Phase
- Phase 2/3
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 135 participants (actual)
- Lead sponsor
- Copenhagen University Hospital, HvidovreUniversity, hospital or other
- Collaborators
- Bispebjerg Hospital
- Study start
- 1 Feb 2024 (actual)
- Primary completion
- 2 Feb 2026 (actual)
- Study completion
- 3 Mar 2026 (actual)
- First posted
- 14 Nov 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
REDOX-AHF compared two oxygen saturation targets in adults admitted with acute heart failure and clinical or radiological signs of congestion. Participants were randomly assigned to a restrictive target of 89-91% or a liberal target of 95-97% for 24 hours. An automated oxygen delivery device adjusted oxygen flow while concealing the assigned target from participants and study staff. The main assessment was lung fluid content after 24 hours, measured noninvasively by remote dielectric sensing (ReDS). The trial was conducted at two Danish hospitals. A total of 135 participants were randomized; 134 remained in the modified intention-to-treat population after one participant withdrew consent. The target of 122 participants with complete primary-outcome measurements was reached. Follow-up continued to day 30.
Detailed description
Background: One million hospitalizations occur each year with a primary diagnosis of acute heart failure in the USA, with comparable numbers in Europe. Most patients with acute heart failure are treated with supplemental oxygen during hospitalization and guidelines recommend initiation of oxygen therapy if SpO2 <90% (class I, level C). However, no clinical trials of oxygen targets in humans with acute heart failure investigating clinically relevant endpoints have been performed.
Primary objective: To investigate the effect of a restrictive vs. liberal oxygenation-strategy in patients hospitalized with acute heart failure.
Hypothesis: Restrictive oxygenation is associated with improved clinical outcome compared to liberal oxygenation.
Design: Investigator-initiated, prospective, randomized, blinded, multi-center, controlled trial.
Intervention: Patients will be randomized 1:1 in the emergency department to either liberal or restrictive oxygenation after providing informed written consent.
(1) Liberal oxygenation group = SpO2 target of 96%. (2) Restrictive oxygenation group = SpO2 target of 90%.
Patients will have nasal cannula or oxygen mask placed as the usual care, and oxygen is titrated to the prespecified target range. Consented patients will be randomly allocated to study groups via the automated web-based system within REDCap. The allocation will be concealed. Time at randomization will be considered as study time zero (T0). All patients will receive usual standard of care except for their oxygen-administration. The intervention-phase will be 24 h, and hereafter oxygen therapy will be at the discretion of the treating physician.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
- Model description
- 1:1 allocation
| Arm | Type | Receives |
|---|---|---|
| Liberal oxygenation group | Active comparator | Drug: OxygenSpO2 target of 96% |
| Restrictive oxygenation group | Active comparator | Drug: OxygenSpO2 target of 90%. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Age ≥ 18 years
- Acute (within minutes to days) onset or worsening of subjective dyspnea
- Oxygen saturation <92% (on arterial blood gas) or need of oxygen
- At least one of the following clinical or radiological signs of congestion:
- 1. Pulmonary rales 2. Chest X-ray or CT with pulmonary congestion 3. Lung ultrasound with multiple B-lines
Key exclusion criteria (4 listed)
- More than 4 hours from hospital admission to randomization
- Suspected infection or sepsis
- Known severe pulmonary disease
- Systolic blood pressure <90 mmHg
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| OxygenPatients will have nasal cannula or oxygen mask placed as the usual standard of care. Patients will be screened and randomized in the emergency department to either liberal or restrictive oxygenation after providing informed written consent and oxygen is titrated to the prespecified target range using an automated feedback device (O2MATIC). Consented patients will be randomly allocated to study groups via the web-based system within REDCap. The allocation will be concealed. Time at randomization will be considered as study time zero (T0). All patients will receive usual standard of care except for their O2 management. The intervention will last for 24 h. After 24 h, patients will be switched over to usual care for oxygen therapy. If the treating physician thinks, that the patient need another oxygenation target and it is thought to be harmful to continue with the allocated target, the intervention-phase can be stopped prematurely. | Drug | Liberal oxygenation group, Restrictive oxygenation group |
Primary outcome
Change in pulmonary parenchymal fluid content from baseline to 24 hours
Time frame: Baseline to 24 hours
Change in pulmonary parenchymal fluid content (%) measured noninvasively using remote dielectric sensing (ReDS; Sensible Medical, Netanya, Israel) from baseline to 24 hours. The 24-hour measurement is preceded by 10 minutes without oxygen supplementation. The published protocol specifies ANCOVA with 24-hour ReDS as the outcome and baseline ReDS as a covariate.
4 secondary outcomes
Arterial blood gas oxygen concentration (PaO2) at 24 hours
Time frame: 24 hours
Patient-reported dyspnoea on a 7-point Likert scale at 24 hours
Time frame: 24 hours
Change in respiratory rate from baseline to 24 hours
Time frame: Baseline to 24 hours
Time to freedom from oxygen-supplementation
Time frame: From randomization to oxygen discontinuation during the index admission
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 26 Oct 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Jens Hove, MD, PhD study chair
Copenhagen University Hospital Amager-Hvidovre Department of Cardiology
Johannes Grand, MD, PhD principal investigator
Copenhagen University Hospital Amager-Hvidovre Department of Cardiology
Ida Taraldsen, MD study director
Copenhagen University Hospital Amager-Hvidovre Department of Cardiology
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2/3 study testing Oxygen in people with Acute Heart Failure and Pulmonary Congestion, run by Copenhagen University Hospital, Hvidovre at 2 sites in Denmark.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 26 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in Denmark. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this combined phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in pulmonary parenchymal fluid content from baseline to 24 hours (time frame: Baseline to 24 hours). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 26 Oct 2026.