Houston doctors to begin experimental treatment for cardiac arrest patients
The research aims to show that the gas known as xenon lessens brain injury in successfully resuscitated cardiac arrest patients
By Todd Ackerman
HOUSTON — Under a once controversial, now accepted practice allowing research without patient consent, emergency room doctors at Memorial Hermann’s Texas Medical Center hospital in January will start using an experimental gas in the treatment of unconscious people whose heart suddenly stopped.
The research aims to show that the gas known as xenon lessens brain injury in successfully resuscitated cardiac arrest patients, most of whom currently either don’t make it or survive with poor neurological function because of the lack of oxygen and sudden reflow of blood.
“I won’t be surprised if this gas becomes a standard of care to help cardiac arrest patients recover,” said Dr. Henry Wang, vice chair for research in the department of emergency medicine at McGovern Medical School at UTHealth, which is conducting the study’s Houston segment at Memorial Hermann. “But we need to do the research to establish its value so it’s important to have community support for the trial,” he said.
To that end, Wang and his research team are holding a series of public meetings around Houston in coming weeks at which they’ll explain the treatment and answer questions.
People who don’t want to participate in the study can opt out by wearing a bracelet during the study that informs the medical team of their non-consent. People can obtain the bracelet by emailing firstname.lastname@example.org.
Team members will contact family members and legally authorized representatives to obtain permission to use the gas, but if no one can be located within two hours and the patient isn’t wearing an opt-out bracelet, he or she will be enrolled in the study.
A worldwide study
The research, to be conducted at more than 70 sites worldwide, is considered important because of the lack of treatment to protect patients against brain damage following cardiac arrest, which occurs when the heart stops beating and blood stops flowing to vital organs. The event kills about 325,000 Americans annually, the majority because their hearts can’t be restarted. But study leaders think some 140,000 patients might benefit from treatment that reduces both fatal and non-fatal injury to the brain.
Hence the appeal of xenon, an anesthetic thought to have neuroprotective properties. Researchers think it can slow the accumulation of oxygen-free radicals, molecules that damage the cells and extend the area of injury when blow flow is restored.
But the only way to determine for sure is a study comparing patients who get the current treatment and patients who get the experimental gas — even though by definition such patients can’t give consent.
Until 1996, that wouldn’t have been possible because of medicine’s requirement to obtain consent before testing any new therapy or procedure. But that year, concerned that the requirement was slowing potential advances in emergency medicine, Health and Human Services made an exception to allow pre-study “community consultation” to suffice for incapacitated patients in some situations. Examples of such consultation are pre-study educational forums, newspaper articles and opt-out procedures.
“There were two conflicting values: informed consent from participants and making sure research to improve treatment can move forward in a timely and effective manner,” said Janet Malek, a professor in the Center for Medical Ethics and Health Policy at Baylor College of Medicine. “Regulators determined that this exception is the best way to balance the two values.”
The exception didn’t go over well initially.
Some ethicists objected when paramedics in five U.S. cities — Houston was one of them — in 2004 began infusing experimental artificial blood into the victims of car crashes, shootings and other life-threatening emergencies without traditional prior consent. The objections became more vocal when a review found patients getting artificial blood had a higher risk of death.
But over the years criticism faded and studies without prior patient consent is now fairly commonly invoked, said Malek.
Half of patients in the xenon trial — leaders last week announced a center in Copenhagen just enrolled the first — will inhale the gas through a breathing tube inserted into their windpipe during hypothermia treatment, cooling done to help protect the brain by stopping the harmful reactions there caused by the reflow of blood after the heart is restarted. The other half will get only hypothermia treatment.
Houston one of 20 U.S. sites
Dr. Mervyn Maze, a professor of anesthesiology at the University of California-San Francisco who first saw the potential application for the gas for cardiac arrest patients, stressed the gas is safe, evidenced by its approval in Europe as an anesthetic. This is its first use in cardiac arrest patients in the U.S., but it was studied on 110 such patients in Finland between 2009 and 2015.
That study found patients who received xenon, along with therapeutic hypothermia, suffered less damage to the brain — and possibly heart — than those who were only cooled. The study was not designed to evaluate survival.
The new study will enroll patients whose cardiac arrest was caused by a heart problem, seen by witnesses and successfully resuscitated within 30 minutes. The patient must be unconscious at the time of arrival at the ER and doctors must decide he or she is eligible to receive cooling.
Houston is one of 20 U.S. sites in the study. Memorial Hermann’s medical center hospital, which annually treats about 100 cardiac arrest survivors, expects to enroll about 50 of the nearly 1,500 patients the study is seeking to test.
“There should be plenty of opportunities to enroll subjects in this important research,” said Wang. “Cardiac arrest remains a major public health issue — only about 10 percent survive and half of those leave the hospital with brain injury — so it’s very important to explore opportunities to improve outcomes and get community support.”