Brain death: 4 tests determine if there is no coming back
A person who has received a brain-death diagnosis cannot breathe on his or her own and is legally dead, in all 50 states.
The New York Times
In one way, the cases are polar opposites: The family of Jahi McMath in Oakland, Calif., has fought to keep the teen connected to a ventilator, while the parents and husband of Marlise Munoz in Fort Worth, Texas, want desperately to turn the machine off. In another way, the cases are identical: Both families have been shocked to learn that a loved one was declared brain-dead — and that hospital officials defied the family’s wishes about treatment.
Their stories raise questions about how brain death is determined, and who has the right to decide how such patients are treated.
“These cases are quite different from those we’ve known in the past,” such as Karen Ann Quinlan, Nancy Cruzan or Terri Schiavo, said Dr. Joseph Fins, director of the medical-ethics division at New York-Presbyterian/Weill Cornell Hospital. He explained: “Those patients could all breathe without a ventilator. They were in a vegetative state, not brain-dead, and that distinction makes all the difference.”
A person who has received a brain-death diagnosis cannot breathe on his or her own and is legally dead, in all 50 states. In two states, New York and New Jersey, hospitals must take into account the family’s religious or moral views in deciding how to proceed in such cases. In all others, including California and Texas, hospitals are not required to consult the family in how to terminate care.
Doctors at Children’s Hospital Oakland pronounced McMath, 13, brain-dead Dec. 9. She developed complications after surgery for sleep apnea and lost a large amount of blood. Munoz, 33, got the diagnosis at John Peter Smith Hospital in Fort Worth after she collapsed from a blood clot when she was 14 weeks’ pregnant. The hospital, citing a state law, refuses to remove the ventilator because it would harm the fetus, now in its 20th week.
The two cases are poignant, in part, because of a biological quirk of the body: The patients’ hearts continue to beat.
Hearts have their own biological pacemaker, and with ventilation, the heart can continue to beat for days, even up to a week. But with more aggressive care, it can last months and longer after brain death, experts say, depending on the health of the patient and how much treatment is provided.
That ventilation saved the fetus in the Munoz case, and probably in the nick of time, said Dr. R. Phillips Heine, director of maternal and fetal medicine at Duke University’s medical school. The diminished blood flow to the fetus when the mother collapsed — she is thought to have been passed out for about an hour before receiving care — “may lead to adverse effects over time, but we have no way to predict that,” Heine said.
A prolonged heartbeat has created the perception of life for McMath’s family, while for Munoz’s relatives it represents a denial of the right to die.
“The way I’ve described this state is that a part of the organism is still alive, obviously, but the organism as a whole — the human being — is gone,” said Dr. James Bernat, the Louis and Ruth Frank professor of Neuroscience at Dartmouth College’s medical school.
Diagnosing a brain as “dead” is a matter of determining the function of its most primitive area, the brainstem. The brain stem, the plug of neural tissue at the base where the spinal cord enters the skull, is the body’s plant manager, sustaining systems such as muscle tone, metabolic equilibrium and ventilation.
Testing its function requires expertise, because people with severe brain injuries are often unresponsive and appear brain-dead when they are not. A coma, for instance, is an unresponsive state that often represents a period of recovery for the brain stem and other areas.
People generally emerge from a coma within two to three weeks after an injury. If they do not, they may enter a vegetative state, in which the brain stem is functioning but higher brain areas are shut down, or what is called a minimally conscious state — in which a patient is occasionally responsive, but not predictably. People who emerge from a vegetative state are thought to pass through a minimally conscious stage before becoming consciously aware.
To determine brain death, four elements are needed, experts said. First, the doctor must rule out other possible explanations for the unresponsive state, such as anesthesia, diabetic coma or hypothermia. An injury must also be established, such as a blow to the head or blood loss.
Doctors then test the function of cranial nerves, including one that runs to the eye and activates blinking; another in the throat that causes gagging; and a third in the inner ear that allows the eyes to focus on an object when the head is moving. Each of these engages the brainstem.
If touching the person’s cornea with a Q-tip does not trigger a blink, or touching the back of the throat brings no gagging, the brain stem is either out of commission or close to it.
The last step is called an apnea test.
To perform this, doctors allow the carbon-dioxide level to slowly increase in the patient’s blood; once the concentration reaches a certain threshold, anyone with a partly functional brainstem will wheeze for breath.
This is the true litmus test for brain death, and it can take about 20 minutes, during which doctors must not leave the room even for a moment, said Dr. Panayiotis Varelas, director of the neuroscience intensive-care unit at Henry Ford Hospital in Detroit.
“If the patient tries to breathe, you abort the test immediately and say the patient is not brain-dead,” Varelas said.
Under human control
The exact timing of these tests and the number of times they are done — some doctors perform them all once; others do so twice, separated by a number of hours — vary from hospital to hospital, surveys have found.
But botched cases are very rare, experts said; people diagnosed with brain death do not come back.
Under New York and New Jersey laws, people can prolong the provision of oxygen to keep a person’s heart beating for religious or moral reasons.
But elsewhere, “life support” is superfluous, if there is no life to support. In that context, the McMath and Munoz cases are different, said Fins, who is working on a book, “Rights Come to Mind: Brain Injury, Ethics and the Struggle for Consciousness.”
The family of Jahi McMath is “hoping (she) will recover and asking to reverse a decision that isn’t under human control,” he said.
“In the Munoz case, the family is asking to reverse a decision that is under human control, and has to do with whether the mother would want to be a mother under these circumstances.”