As Bobbi Kristina Brown enters her third month in a coma, her family faces an excruciating choice: Keep the 22-year-old alive on machines with little hope for recovery, or withdraw life support and let nature take its course.

The agonizing decision is one faced by many families, and each situation is unique, a top expert tells Newsmax Health.

But one thing is common to all end-of-life situations: They are easier if the patient has left instructions about how they want to be treated.

Brown, the daughter of the late singer Whitney Houston, was found face-down in her bathtub on Jan. 31 and now is being kept alive in a critical care facility.

Like most people, especially patients so young, Bobbi Kristina apparently did not have an end-of-life directive that would instruct her family of her wishes, according to reports.

“Whether they’re young, old, or in-between – people need to make their wishes known,” Marc Leavey, M.D., told Newsmax Health.

“Years ago, we didn’t have the means to keep people alive this way. If something happened, you were going to die. But now, we can use machinery to take care of a person’s life functions.

“We can keep them breathing, their heart beating, and their kidneys functioning. The only thing we really can’t fix is their brain. But if the body is otherwise intact, we can keep someone going indefinitely, and that’s actually a real problem,” said Dr. Leavey, an internist at Mercy Medical Center in Baltimore.

Part of the problem is that we as a society have become more distanced from death, and more convinced that it is the job of doctors and hospitals to keep us alive no matter what, said Dr. Leavey.

“Before modern technology came along, when mom and dad got old and sick, they’d be kept in the back bedroom and the family would take care of them and the kids would see that death was a part of life.

“Now mom or dad is hooked up to a machine in a hospital and their children are notified by a phone call that they’ve died. We’ve distanced it, and as a result, people don’t want to talk about it anymore,” Dr. Leavey said. “We need to start talking about it.”

There are myths about end-of-life directives that keep people from executing them, Dr. Leavey said.

“People think it’s an order to die, but it can be the opposite. You can say, ‘I don’t want to live under certain circumstances, or you can say, ‘Do everything you can to keep me alive,’” he said.

Such directives can be changed in the event that people decide differently later, he noted. “People do that all the time,” he added.

And age should not be a factor. “We ask teenagers when they get their first driver’s license if they want to become organ donors. That may seem odd if you think about it, but this is not that different,” said Dr. Leavey.

“Bobbi Kristina may have not wanted to be kept alive, hooked up to a machine and tubes, or she might have wanted to be kept alive no matter what. But we’ll never know because she didn’t say. And now it’s too late,” he said.

End-of-life instructions are usually put into a legal document known as an advance directive. States vary in their requirements, but such directives can include:

• A living will: This tells your doctor how you want to be treated if you are dying or unconscious and cannot make decisions about emergency treatment. You can stipulate which procedures you would want, which ones you don’t, and under which conditions each of your choices applies.

• A durable power of attorney for healthcare: This legal document names a healthcare proxy, which is someone such as a family member to whom you give authority to make medical decisions for you when you are not able to do so.

• A DNR or “do not resuscitate” order: This document tells the medical staff in a hospital or nursing facility that you do not want them to try to return your heart to a normal rhythm if it stops or is beating unevenly. You can also execute a non-hospital DNR to keep ambulance personnel from resuscitating you. There are similar forms for CPR and also a DNI (on not intubate) order if you do not want to be put on a breathing machine.

You can download forms for an advance directive in your state by going here.