Newswise — Emergency medicine physicians at The University of Texas Health Science Center at Houston (UTHealth) are seeking community input about a proposed clinical trial assessing the efficacy of inhaling xenon, a medical gas, to mitigate brain injury and preserve cerebral function in cardiac arrest patients.

Cardiac arrest is when the heart stops beating suddenly and blood stops flowing to vital organs, including the brain, heart, and kidneys. According to research from the American Heart Association, more than 325,000 cardiac arrests occur outside of a hospital setting each year in the U.S. The average survival rate of out-of-hospital patients who receive emergency medical care is just 10.6 percent. Survival with good neurological function is only 8.3 percent.

“Once a victim has been successfully resuscitated from cardiac arrest, unfortunately, injury to the brain continues,” said Henry Wang, MD, professor and vice chair for research in the Department of Emergency Medicine at McGovern Medical School at UTHealth. “The brain has a hard time handling the reflow of blood. We are hopeful that the inhalation of xenon will help the brain to better endure this stress, resulting in better neurologic outcomes. This research aligns with our goal to further the science of resuscitation and make the life-saving process as safe and effective as possible.”

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, a neuroprotector, could potentially slow or halt the accumulation of the harmful molecules on brain cells.

In the proposed phase three trial, patients will inhale xenon through a breathing tube inserted into the windpipe during hypothermia treatment, which is the cooling of the body to stop destructive cerebral mechanisms and help protect the brain, within five hours of cardiac arrest. A previous phase two trial involving 110 successfully resuscitated patients showed those who were administered xenon, along with therapeutic hypothermia, suffered less damage to the brain and possibly the heart than survivors who were only cooled. The results of that trial were published in JAMA.

This study will enroll successfully resuscitated patients whose cardiac arrest is due to a heart problem. Only patients whose cardiac arrest was seen by witnesses and who were successfully resuscitated within 30 minutes will be considered for the study. The patient must be unconscious at the time of emergency room arrival and doctors must decide that the patient is eligible to receive cooling.

Because unconsciousness is a requirement to enroll in the study, informed consent is not feasible. Researchers will contact family members and legally authorized representatives to obtain permission, and if neither can be located within two hours, the patient will be enrolled.

In order to inform the community of the proposed study, Wang and members of the research team are presenting the research study and answering questions at a series of meetings with groups in and around Houston. For information on the meetings, please email [email protected]. Researchers are also running a social media campaign to inform the public.

The research is funded by NeuroproteXeon and Cato Research, and is scheduled to begin in early 2019. Researchers hope to include 1,400 patients at 30 to 50 participating locations worldwide, and expect about 50 patients to be enrolled at UTHealth and Memorial Hermann-Texas Medical Center.

If you do not wish to participate in this proposed research study, please email [email protected] to obtain an “opt-out” bracelet that must be worn for the two-year duration of the study.


For more information about this research study, please visit