"For the time being, he's dependent on machines," the doctor said, adding that there were no immediate plans to put the former leader on a respirator.
Last week the retired five-star general was hospitalised with anaemia and low blood pressure, as well as problems with his heart, kidneys and lungs.
"Even though he is sick, Suharto must be held accountable for crimes he committed in the past"
Hasan, a protester outside the hospital
He has since improved and relapsed several times.
A series of strokes also left him with permanent brain damage and impaired speech.
"His kidney function is still poor," Joko Raharjo, a member of the medical team, said. "That's why he needs dialysis treatment."
Suharto has been in and out of hospital since he was forced to resign following intense public pressure at the height of calls for reform sparked by the 1997-98 Asian financial crisis.
Calls for accountability
The sudden deterioration in his health condition had prompted calls for legal proceedings against him to be dropped but the government said this week it would press ahead with a civil case.
On Wednesday, a dozen student protesters gathered outside the hospital calling him to answer for his corrupt activities during his 30-year presidency.
"Even though he is sick, Suharto must be held accountable for crimes he committed in the past," a protester called Hasan said.
"Many people were killed when he rose to power. He used his influences to further his own interests and the interests of his family."
In recent days Suharto has been visited by Susilo Bambang Yudhoyono, Indonesia's current president, cabinet ministers, Muslim leaders and members of the ruling party.