Xenon for Post Out of Hospital Cardiac Arrest Syndrome – The XePOHCAS Study

Informed consent is the process where the researchers share key facts about a research study with a person to help them decide whether or not to take part in the research study. Taking part in research is voluntary and people have the right to refuse to take part in a research study. In some emergency situations, people who are taking part in a research study are not able to give their consent due to their condition. The XePOHCAS study is a research study in which patients who have been successfully resuscitated after cardiac arrest may be included in the study without their consent. 

What is the purpose of this research study?

Cardiac arrest is when the heart stops beating suddenly and blood stops flowing the vital organs including the brain. A cardiac arrest usually causes death if it is not treated within minutes and transported to a hospital. Even after a person who has a cardiac arrest is resuscitated, injury to vital organs such as the brain continues as the brain tries to handle the reflow of blood.

According to a 2014 study published in Nature, after organs are starved of oxygen and nutrients, a molecule called succinate builds up in extremely high levels. When the blood flow is restored, the succinate causes the generation of harmful molecules called oxygen free radicals, which damage the cells and extend the area of injury in the organ.

Xenon, which has anesthetic properties, could potentially slow or halt the accumulation of the harmful molecules on brain cells. The XePOHCAS study is being done to find out whether xenon gas can help reduce brain injury and improve brain function after a cardiac arrest. This research study is sponsored by NeuroproteXeon and CATO Research and will be at UTHealth and Memorial  Hermann Hospital.

Any successfully resuscitated cardiac arrest patient over the age of 18 years whose cardiac arrest is due to a heart problem will be considered for joining the study. The patient should be unconscious at the time of arrival to the emergency room and doctors should have decided that the patient is eligible to receive cooling. Only patients whose cardiac arrest was seen by witnesses and who were successfully resuscitated within 30 minutes after the cardiac arrest will be considered for the study.

The company NeuroprotecXeon has recently completed a research study in which 110 successfully-resuscitated cardiac arrest patients were given Xenon. This study showed that patients who had successful resuscitation within 30 minutes had less damage to the brain and possibly to the heart.

What will happen in the research study?

In this study, Xenon (XENEXTM)) will be given through a special breathing machine called the Xenex Delivery System. Xenon is a gas that is present in the atmosphere in small amounts. The breathing machine mixes XENEXTM and oxygen in a breathing tube inserted into the windpipe.  Both XENEXTM and the Xenon Delivery System are considered experimental because they have not yet been approved for this purpose by the United States Food and Drug Administration.

What are the risks of Xenon?

Xenon gas has been used for many years at high levels (higher than the level used in this study) to help during surgery and other procedures as an anesthetic. Just like other anesthetic drugs, risks of XENEX include changes in heart rate or blood pressure, increase in the air pressure in the lungs, and nausea and vomiting. These changes are temporary and will stop after the XENEX treatment is stopped.

Why is it not possible to get the patients’ consent before including them in the study?

Normally, researchers get permission before a person can be included in a study.  This is called informed consent. During the informed consent discussion the researcher explains the research study including risks and benefits of joining the study and answers questions to help the person decide whether or not to join the research study.

In this study, patients are unconscious and therefore cannot give permission to participate in the study. Researchers will do their best to contact and explain the study to family or legally authorized representative (LAR) and ask for their permission to enter the patient to in the study. If a family member or LAR is not located within 5 hours, the patient will be included in the study.  

When a family member or LAR is located they will be asked to give their permission to continue in the study. If the patient wakes up, researchers will inform the patient about the research study and ask for their consent to continue in the study.

How many patients will be included in this research study?

This research will include 1400 patients at 30-50 locations across the world. Around 50 patients will be included in the study at UTHealth and Memorial Hermann Hospital.

When will the study start?

We plan to start this research study in the winter of 2018 and the study is expected to run for about 2 years. We hope to complete the study by early 2020.

If I do not wish to be included in this research study, how can make my wish known?

If you do not wish to participate in this research study, please email us at clinicaltrials@uth.tmc.edu. We will be happy to provide you with an ‘opt-out’ bracelet that you should wear for the duration of the study.

For more information about this research study, please visit http://efic.npxe.com/ and https://clinicaltrials.gov/ct2/show/NCT03176186 or write to the research team at clinicaltrials@uth.tmc.edu.

For more information about emergency exception from informed consent visit planned emergency research without consent.