Dr. Pichurko said treatments for the young are not always good for the elderly.

"Illness such as pneumonia puts stress on other organ systems. And so we worry about worsening diabetes, kidney function, liver function. Many of those can deteriorate when we are doing our best to treat a respiratory infection," he said.

Although some people have said Mandela should be allowed to die, Dr. Pichurko said the decision to end treatment is never easy.

"The best decision is made in partnership between patient and doctor. The doctor is ethically obligated at some point, if that point is reached, to indicate when medical treatment may be futile," he explained.

Dr. Pichurko added that age is a factor, but only a minor one. Some people are healthy at 95. Others are not. For the elderly, it's important to try and prevent exposure to viruses or certain bacteria. And if an infection does occur, to get good medical care within 48 hours.