Doctors treating Bobbi Kristina Brown appear to be taking steps to limit brain damage, medical experts say.
The 21-year-old daughter of singers Whitney Houston and Bobby Brown has been in a medically induced coma since late Saturday, after she was found unconscious in a bathtub at her home in Roswell, Ga.
Police said they found no evidence that drugs or alcohol were factors in Brown's condition.
Inducing coma is a common approach to treating someone who has been deprived of oxygen, says Paul Vespa, a professor of neurosurgery and neurology and director of the neurointensive care unit at the University of California-Los Angeles.
Brain cells die quickly without oxygen, says Robert Glatter, an emergency physician atLenox Hill Hospital in New York. Neither Vespa nor Glatter is involved in Brown's case.
Putting a patient into a medically induced coma reduces the brain swelling and inflammation that can cause brain damage, Glatter says.
As brain cells die, they release chemicals that can cause further brain damage, Vespa says.
To slow that process, doctors often sedate patients and lower their body temperatures, which slows the "chemical cascade," Vespa says.
Doctors can lower body temperature with cooling blankets and by giving patients cooled intravenous saline, says Galen Henderson, director of the division of neurocritical care at Brigham and Women's Hospital in Boston.
"Cooling therapy" is also used after heart attacks and when newborns are deprived of oxygen during delivery, Vespa says. The same principle has allowed children to survive after falling through ice into freezing water, he says.
"It's not a guarantee, but it's probably the only kind of therapy that has worked for this kind of brain injury," he says.
Brown's youth gives her a better chance of survival than an older person would have, Vespa says.
Doctors typically reduce a patient's temperature for 72 hours before allowing the body to gradually warm up and emerge from the effects of sedation.
Once the body is normal temperature, doctors can examine the patient and run tests such as an EEG, MRI or CAT scan to assess the extent of brain damage and a patient's likelihood of recovery, Vespa says.