A Do Not Resuscitate, or DNR, order is a written order from a doctor that resuscitation should not be attempted if a person suffers cardiac or respiratory arrest. Such an order may be instituted on the basis of an advance directive from a person, or from someone entitled to make decisions on their behalf, such as a health care proxy; in some jurisdictions, such orders can also be instituted on the basis of a physician's own initiative, usually when resuscitation would not alter the ultimate outcome of a disease, and is designed to prevent unnecessary suffering.
(Above from Wikipedia)
My wife's cousin Barbara has had a DNR order for years. She thought it made sense. She didn't want to live "like a vegetable."
She was recently hospitalized. Her heart stopped. Her regular doctor was not at the hospital, and no one at the hospital knew that there was a DNR order. She was resuscitated and is doing fine and will be coming home soon.
DNR orders may make sense in some cases, but if it was is followed in this case, Barbara would be dead. If you or a loved one has a DNR order, you should review it.