The unconscious man in his 90s was brought to an emergency room where Dr. Douglas White was a critical care physician. The staff couldn’t find any relatives to make medical decisions on his behalf.

In a recent New York Times article, Paula Span writes about what experts are calling patients who are unbefriended.

“He had outlived all his family,” recalled White, who now directs an ethics program at the University of Pittsburgh Medical Center. “We were unable to locate any friends. We even sent the police to knock on his neighbors’ doors.”

Nobody could find an advance directive, either. In the end, the hospital’s ethics committee had to help guide the medical team to decisions about continuing life support.

Experts describe patients like this one as “unbefriended.” But you can also be unbefriended, even if you do have friends and family, if you are incapacitated and haven’t appointed someone you trust as a health care proxy.

Lots of people already fall into this troubling category. Sixteen percent of intensive care unit patients in one West Coast hospital were unbefriended, according to a 2007 study for which White was a co-author. Another of his studies reported that of I.C.U. patients who died, 5.5 percent were unbefriended or — some ethicists find this a more precise, less stigmatizing term — unrepresented.

The numbers are likely to increase as so much of the population ages, in part because dementia rates rise with age. “We saw a growing pattern: More and more patients, who lacked decision-making capacity, had no available surrogates and had not completed an advance directive,” said Martin Smith, director of clinical ethics at the Cleveland Clinic.

The Cleveland Clinic has adopted protocols that provide more oversight as the medical decisions for an unbefriended patient grow more serious. For a procedure that ordinarily requires informed consent — a transfusion or surgery, for example — the attending physician, a second staff physician and a staff ethicist must all agree that it’s in the patient’s best interest.

In Indianapolis, the Center for At-Risk Elders, a nonprofit legal advocacy group, trains volunteers — social workers, lawyers, retired nurses, medical and law students — to serve as guardians who make health care decisions for the unbefriended.

To read more on this topic, visit http://my.clevelandclinic.org/ and an article that recently appeared in the Journal of American Geriatrics Society at http://onlinelibrary.wiley.com/doi/10.1111/jgs.13096/abstract.