The one person most important to you when you go to the hospital is your doctor.

If you can find him. Or her.

If you know who "your doctor" is among all the people in white or other hues who pop in and out of your room.

If you can communicate the things that matter in the two minutes, say, that your doctor may spend in your room.

All these things have become problems as hospitals have become complexes of machines, technicians and super-specialists, necessary for cures but seemingly minimizing the role of the doc at the bedside.

Yet "your doctor" is still important. What can you do about it?

First, realize that the old family physician who had open-ended privileges to do anything at all to you, even operate on you, is and should be obsolete. No doctor can know all that needs to be known about many a sorely or bafflingly ill patient.

Much of today's medicine must be team or committee medicine, with an interplay of opinions on dealing with the puzzles of human disease.

Too often, however, says Dr. Judah Folkman of Children's Hospital Medical Center in Boston, a super-specialist himself, "you come in, you're assigned many doctors, but you feel no one doctor is looking after you.

"A doctor who develops an insight into the labyrinth of his patient's ways can tell from a fleeting facial expression when something is wrong. It is a signal that alerts the patient's doctor but makes no sense at all to the transient consultant.

"It's up to someone to say, 'This is enough. This patient needs one doctor.' "

Dr. Edward Campion of Massachusetts General Hospital has put it this way: "Today solo practice is fading, and the ideal of the 'super-doctor' who knows all, does all and never needs peace or privacy should also fade. Continuity now often means continuous care with a single group or team of health providers.

"The essential ingredients for continuity are that such care be coordinated, that the professionals communicate clearly and . . . that there remain a single, unequivocal family physician. The more complex the case, the greater the need for that primary physician as a continuous overseer, coordinator and advocate."

That doctor may still in many cases be your regular doctor. But your doctor may lose control in many hospitals or conditions.

"I think 'your doctor' should be the referring physician or the physician who first sees the patient," Folkman said. That is not always possible -- or desirable -- but someone, he insisted, must say, "I will be that patient's doctor."

The lesson for you? It may be up to you, the patient, to say, "Who is my doctor here?"

If possible, ask "Who will be in charge of my care?" before entering the hospital or on being admitted.

If the answer is unclear or not available yet, keep asking. Insist. Say, "I want to know who is responsible for me."

You indeed may have to keep asking. Residents -- young doctors in training -- may be writing the orders for your care. They may be reporting to your admitting doctor. Or to an "attending" staff member who comes by at times. Or a staff doctor who keeps a more or less close eye on your care. It may, if you're very sick, be a very close eye. But it may not.

If your condition suddenly changes, the "physician-of-record," the doctor in charge, can change. A heart patient being treated by a cardiologist has a stroke in the hospital and is shifted to the neurology service. An eye patient being cared for by an ophthalmologist develops a bleeding ulcer. A gastroenterologist takes over.

Amazingly, say Drs. Ronald Gots and Arthur Kaufman (in their fine "The People's Hospital Book," Crown, 1978), patients -- and their families -- are often not told of the change. They tell how in one large hospital "one of us came across a patient who had been lost for a week."

The patient was in a surgery ward because of suspected appendicitis. He improved without surgery, so a surgery resident summoned an internal medicine resident for a consultation.

The new diagnosis was either an ulcer or inflamed pancreas, so the surgery resident sent him to a medical ward, with new orders for the nurses. The medical resident was not informed, so didn't look in on him.

Two days later a new set of medical residents took over. They, too, knew nothing about the patient, who "after six days . . . asked one of the nurses where his doctor was and when he was going home."

Fortunately, Gots and Kaufman write, he got well on his own, but "we have seen other cases . . . where confusion about lines of responsibility has culminated in serious patient injury or death."

They tell of a 4-year-old girl in an asthmatic crisis. Her doctor called in a pediatrician. Together, they treated her. The initial doctor thought he had now turned the case over to the pediatrician; the pediatrician thought he was still only the consultant and turned to other patients. Neither wrote medication orders. Within hours, the child was found gasping for air, with permanent brain damage.

The moral, for patients and family: Know who the responsible doctor is at all times. Ask doctors, nurses, anyone you see. If the answer is unclear, phone the hospital's patient representative, if there is one.

If the answer is still vague, holler. Go to the office of the hospital's president or chief administrator. Or chief of medicine. Or chief of surgery. Insist on finding that all-important person, a doctor who will take charge, see you regularly and keep you informed.