Skip to content
Clinical Trials – home

Rare diseases

Investigational molecules

Locations

Our offerNewsroom

Not yet recruiting

A Study of High-Concentration Oxygen Treatment in Patients with Heart Failure, Pulmonary Hypertension, and Coronary Microvascular Dysfunction

Verified siteRegistered drug
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

What is this trial about?

A plain-language summary of the goals, design and what participants do

This study focuses on several heart and lung conditions including Pulmonary Hypertension, Coronary Microvascular Dysfunction, Heart Failure, and conditions involving low oxygen levels in the body (Hypoxia). The study aims to understand how high-concentration oxygen affects blood flow and blood vessel resistance in different parts of the body, particularly in the heart and lungs.

The treatment being studied is Conoxia, which is a medical-grade oxygen given in its liquid, extremely cold form (cryogenic). This pure oxygen will be administered to participants to examine its effects on blood circulation. The study will measure how the heart pumps blood and how blood vessels respond to this oxygen treatment.

During the study, measurements will be taken at different time points to see how quickly the body responds to the oxygen treatment. The study will look at blood flow changes in various parts of the body, including the heart's small blood vessels and the blood vessels in the lungs. These measurements will help understand how oxygen treatment affects blood circulation throughout the body.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial procedures

    Your participation begins with a standard heart catheterization procedure, which has been determined as clinically necessary for your condition

    This procedure will help examine blood flow in your heart vessels and measure blood pressure in your heart and lungs

  2. Step 2

    Oxygen administration

    You will receive 100% oxygen through oral delivery

    The oxygen will be administered in its liquid form (medical grade, cryogenic)

    The administration will last for 10 minutes

  3. Step 3

    Measurements

    Blood flow measurements will be taken at three specific points:

    At the beginning of the procedure (baseline)

    5 minutes after starting oxygen administration

    10 minutes after starting oxygen administration

  4. Step 4

    Monitored parameters

    During the procedure, several measurements will be taken:

    Blood flow output from your heart

    Blood pressure in your heart and lung vessels

    Blood vessel resistance in your heart and lungs

    These measurements will help understand how oxygen affects blood flow in your vessels

  5. Step 5

    Duration

    The entire procedure will be completed during your scheduled heart catheterization

    No additional visits will be required beyond your regular medical appointment

Who can join the trial?

7 criteria

  • Must be at least 18 years old
  • Must be scheduled for one of these medical procedures:
    • Coronary Flow Test (CFT) showing problems with small blood vessels in the heart
    • Right Heart Catheterization (RHC) to check for high blood pressure in the lungs
    • Left and Right Heart Catheterization as part of evaluation for heart transplant or mechanical heart pump
    • Must have clear coronary arteries (no significant blockages in heart blood vessels - less than 50% narrowing)
    • Must be able to understand and willing to sign an informed consent form
    • Can be either male or female

Who cannot join the trial?

15 criteria

  • Age under 18 or over 65 years old
  • Pregnancy or breastfeeding
  • Severe pulmonary diseases (diseases affecting the lungs) other than those being studied
  • Recent heart attack or unstable heart conditions
  • Inability to lie flat for the duration of the examination
  • Current participation in other clinical trials
  • Known allergies to medications used in the study
  • Severe kidney or liver dysfunction
  • Uncontrolled high blood pressure
  • History of blood clotting disorders
  • Mental conditions that could affect ability to provide informed consent
  • Active infections or fever
  • Use of medications that could interfere with the study results
  • Inability to follow study procedures
  • History of adverse reactions to oxygen therapy
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

We usually reply within a few days

Verified sites

All sites with verified contact details – recruitment status may not be available; ask directly

Trial locations

Where you can join this trial

Countries are shaded by recruitment status. Click a recruiting country to ask about joining there.

Not yet recruiting
Not finding your country?

Not sure what to do next?

Joining a clinical trial can seem overwhelming. We guide you step by step, so you know exactly what to expect and how we support you through the process.

See the full process and FAQ

Investigated drugs

Oxygen (100% concentration) - Pure oxygen administered as a medical gas. This therapy involves breathing in oxygen at high concentration levels. It's commonly used to increase the amount of oxygen in the blood. During this study, researchers are examining how this high concentration of oxygen affects blood flow and blood vessel resistance in different parts of the body, including the heart, lungs, and throughout the circulatory system.

What is already known about the treatment

Medical Oxygen – A colorless, odorless gas administered through inhalation via nasal cannula, face mask, or other respiratory delivery systems. Medical oxygen is an essential treatment approved worldwide for various cardiopulmonary conditions, primarily used in treating hypoxia, pulmonary hypertension, and heart failure. It works by increasing the oxygen concentration in the blood (improving oxygen saturation), which enhances tissue oxygenation and reduces the workload on the heart and lungs. This pharmacologically classified respiratory agent directly affects the pulmonary and systemic circulation by causing vasodilation in hypoxic tissues while potentially inducing vasoconstriction in the pulmonary vessels, making it particularly useful in treating coronary microvascular dysfunction.

Investigated diseases

  • Pulmonary Hypertension

    A condition where blood pressure in the pulmonary arteries becomes abnormally high. The pulmonary arteries carry blood from the heart to the lungs. This increased pressure makes it harder for the heart to pump blood through the lungs. The blood vessels in the lungs become narrowed and thickened over time.

  • Coronary Microvascular Dysfunction

    A condition affecting the small coronary blood vessels that branch off from the larger coronary arteries. These tiny vessels don't function properly, leading to reduced blood flow to the heart muscle. The small blood vessels may not dilate properly or may have irregular contractions.

  • Hypoxia

    A condition where the body or a specific part of the body doesn't receive enough oxygen. It occurs when oxygen levels in the blood fall below normal levels. The body's tissues need oxygen to function properly, and when oxygen levels are too low, cells begin to work less efficiently.

  • Heart Failure

    A chronic condition where the heart cannot pump blood effectively enough to meet the body's needs. The heart muscle becomes too weak or stiff to work properly. This leads to fluid buildup in the lungs and body tissues, causing symptoms such as shortness of breath and swelling.

Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-516279-34-00Protocol codePaNaMa code: 113071Estimated enrolment24 patientsSponsorStichting Radboud universitair medisch centrum

sourced from the EU Clinical Trials Register and site verification

Want to learn more about this trial or check if you can participate?

Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

ClinicalTrials.eu

Every clinical trial in Europe, in plain language.

Explore the full ecosystem of clinical research in Europe.

Search trials

Legal notice · Published by CTIN POLAND sp. z o.o., ul. rtm. Witolda Pileckiego 67/109, 02-781 Warsaw, Poland · KRS 0001111334 · REGON 528919042 · NIP 9512598637

© 2026 Clinical Trials EU – European Clinical Trials Information Network

GDPR compliance, ISO 9001 and ISO 27001 certified (LL-C Certification)

On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

This service is not affiliated with the European Commission, the EMA, or the official CTIS system. Most information comes from publicly available international clinical-trial registries, supplemented by data from academic sites, national regulators and commercial sponsors. On this site, “treatment” and “therapy” mean a medicine being tested in a clinical trial. Its safety and effectiveness in the use being studied are not yet confirmed, some participants may receive a placebo or a comparator, and taking part does not guarantee a health benefit. The doctor at the research site decides who can take part. This site provides information, not medical advice. Certain content and visual elements on this website have been generated or enhanced using artificial intelligence (AI).