American medical care is undergoing its most drastic upheaval since the dawn of the age of science. About 100 years ago, new discoveries -- germs, antisepsis, X-rays, vaccines -- began to transform ancient hit-or-miss medicine into effective medicine.

In contrast, today's changes and upheavals have more to do with business and economics than with science.

Whether they will improve or degrade our medical care is uncertain. Whether adequate steps have been taken to guard that care is also uncertain.

Among these massive new forces are:

* The beginning of limits on medical and hospital spending, and how much government, businesses and health insurors will pay doctors and hospitals. This is forcing almost all medical care providers to reassess how much care they will give us.

* An explosion of new health plans: HMOs (health maintenance organizations), similar IPAs (doctors' independent practice associations) and the like. These take over all of their patients' medical and hospital care for a fixed monthly payment, rather than a fee for every service. This makes these programs take great care to avoid "over-treatment."

* A takeover of a growing share of hospital and medical care by investor-owned, profit-seeking businesses, like Humana Inc., which sponsors the artificial heart transplants, or one of the national hospital chains now bidding to run George Washington University Hospital.

A striking fact about all three of these no less than revolutionary movements is that none has as its primary goal making patient care better.

The new cost controls include either an unspoken or often plainly spoken dictate to hospitals and doctors to "do less" for patients, because doing more is so expensive. These rules are, in effect, a beginning of rationing American health care.

The new HMOs and other total-care plans can survive only by restricting what they do for their patients, compared with the old way of ordering virtually unlimited tests, surgery and hospitalization.

The main purpose of for-profit corporations, including hospital and health care corporations, is to make profit. Hospital chains often avoid money-losing patient services.

Although none of these new movements was invented primarily to improve medical care, some -- or even all -- might do so. Every conscientious doctor or student of health care knows that too much testing, treatment and hospitalizing can hurt rather than help patients.

For example, Dr. Eugene Robin of Stanford University tells this story. A woman of 78, until then healthy, developed a respiratory infection that did not necessarily require hospitalization. She was hospitalized nonetheless. Routine blood testing seemed to show a low potassium level. Though there were no other signs of potassium deficiency, her doctor ordered potassium -- not always innocuous -- inserted by vein.

Monitoring was inadequate, and the woman's heart stopped. Post-mortem examination showed she had almost certainly died of potassium intoxication. "Had she not been admitted to a hospital, she probably would have survived," Robin writes in "Matters of Life and Death: Risks and Benefits of Medical Care" (W.H. Freeman, 1984).

The wildly escalating costs of care -- too long ignored by the bill-payers, mainly government and employers -- triggered both the new cost controls and big business methods. Without new controls and efficiencies, rising costs would rapidly lead to increasing rationing of care, like the British system where rationing lets some heart and kidney disease patients die because the waiting lists are too long or the rules on who gets costly care are too restrictive.

The government officials who plan the new cost controls, the organizers of HMOs and IPAs and the presidents of health care corporations all pledge to maintain and even improve "quality," meaning what is done for the individual patient. Yet the patient is often the last person mentioned in many of the discussions of these changes.

"The public has been insufficiently informed about all these things," said Dr. Marcia Angell, deputy editor of The New England Journal of Medicine, in a recent interview. "Does the public really want access to health care to be limited in the name of cost-saving? At this point the public is not involved in the dialogue."

Dr. Walter E. O'Donnell, a respected Gloucester, Mass., internist, wrote in Medical Economics magazine three years ago: "In any ranking of priorities in the health care field these days, the patients -- whom I've always regarded as primary and central -- are being assigned a lower and lower rung on the ladder."

"We seem to be headed toward a multitiered system" of care, warns Walter McNerney, former head of the national Blue Cross-Blue Shield organization, now a professor at Northwestern University. A survey of 1,000 health care professionals, sponsored by the American College of Hospital Administrators, found wide agreement that only the well-fixed will get top-level care in the future, and that within the next decade persons who lack health insurance or are covered by Medicare or Medicaid may find medical care harder to get and poorer in quality.

In a recent issue of Medical Economics, Roger Rusley, a Denver medical practice consultant, told doctors: "You'll find the health care market breaking down into three classes, much as the airlines do," with Class 1 "for those who put the quality, comfort and convenience of their health care above cost considerations," Class 2 for "patients who consider cost first," so belong to an HMO or like plan, where "the choice of a physician will be somewhat limited," and Class 3 for those covered by government-subsidized plans like Medicare and Medicaid.

"To draw" Class 2 and 3 patients and still stay ahead, he advised, "keep your fees competitive and hope to profit from higher volume," use auxiliary personnel like nurse practitioners and "see a maximum number of patients in a minimum amount of time."

A "minimum time" doctor may not be the doctor for you. One patient of a major health plan says: "I went in because of something growing on a toe. It turned out to be a fungus infection. I wanted to know more about it and my alternatives. But I could tell I had been alloted a 10-minute appointment, and when my 10 minutes were up I wasn't done, but the doctor was."

Other profound changes on the health scene are taking place simultaneously:

* There are growing numbers of older patients, not just in their sixties and seventies, but in their eighties and nineties. Given medicine's growing ability to stave off death by costly interventions, their very survival could trigger even more draconian efforts to limit both treatment and spending.

* There are rapidly growing numbers of doctors, and there may soon be a large surplus. Practicing physicians grew in number from 311,000 to 435,000 between 1970 and 1980; their ranks will increase by another 54 percent in 15 years. Will this mean a growing number willing to take good care of us for curtailed fees? Or, going by some past trends, will it mean more doctors seeing fewer patients, while maintaining high incomes via new technological procedures? No one knows.

* Finally, there are the many super-expensive new technologies that -- unlike vaccination and other public health measures that benefit many -- threaten to consume an ever greater share of the health dollar to treat a relative few.

One current example: artificial and transplanted hearts. By one estimate, from 25,000 to 50,000 persons a year could potentially benefit from either an artificial or transplanted heart. At perhaps $150,000 per procedure, such "new hearts" alone could add $7.5 billion to the nation's medical bill.

The federal government so far has made only a few weak attempts to limit the proliferation and often needless duplication of new machines and technologies. But the government's main new response to the entire cost problem is more dramatic. In October 1983 it began paying hospitals only a fixed sum, based on diagnosis, for most Medicare hospitalizations, meaning 35 or 40 percent of the average hospital's business.

A Medicare patient is now assigned to one of 468 diagnosis related groups (DRGs). If a hospital spends more than the DRG reimbursement, it makes money; if it spends less, it loses. So hospitals are concentrating on discharging Medicare patients swiftly.

The apparent effects of DRGs and other pressures going back several years -- pressures by government and private health insurors -- are striking. Hospital beds are increasingly empty. The average length of hospital stay fell by 7 percent during 1984. The average stay of a patient over 65 has dropped by a day and a half since 1981.

The new Reagan budget would now freeze hospitals' DRG payments, instead of giving them an expected annual raise -- further increasing the pressure to get the older patient out of the bed. At the same time, Medicaid -- combined federal-local help for some medically indigent -- has been held far below the potential need.

There are already stories of older patients being shoved out of hospitals too early. A New Jersey medical examiner (in a state where DRGs aply to all patients) said some patients died in ambulances bringing them home from the hospital. A Milwaukee patient in her seventies was discharged from the hospital and sent to a nursing home though still suffering from pneumonia and congestive heart failure. She died before she could be readmitted to the hospital. The nursing home's administrator maintained she was one of several patients similarly "dumped" by a hospital.

Incidents like these also happened before DRGs. American Medical Association officials, no friends of DRGs, say it is too early to assess the DRGs' effects.

Now, however, the government plans to start "ratcheting down" on hospital payments. To see that hospitals don't abuse the DRG system -- by soliciting profitable short-term admissions or "over-diagnosing" patients to boost reimbursements -- the Department of Health and Human Services (HHS) will rely on local watchdogs called PROs, or Professional Review Organizations. The PROs are also supposed to monitor the quality of hospital care to prevent premature "dumping" or other harm to patients.

Dr. John Johnson, Washington legislative representative for the Kaiser health plans, thinks the PROs will be "burdened" primarily with monitoring "inappropriate, excessive and unnecessary" treatment from a cost-control viewpoint. They "will not assure optimal care," he believes, only care that meets a "least common denominator." This sounds like something less than the best.

HHS agencies have started some studies to try to monitor DRG care and "outcomes." Whether these studies will be adequate or not is another matter. Jerome Brazda, well-informed editor of the weekly Washington Report on Medicine & Health, sees "really no effective monitoring on behalf of the patient."

"Quality is hard to measure," and nobody is funding all the necessary research or asking the necessary questions, maintains Dr. Karen Davis of Johns Hopkins University, a Carter administration health official. "All this cost-saving may be worth the effort. What is troubling is that nobody is really asking, 'Is it good for the patient?' "

Dr. William Schwartz of Tufts University, a student of Britain's medical rationing, thinks we will not know the answer to that question until we, too, begin to see massive rationing. He thinks mounting costs and an aging population will make that inevitable.

How hard do hospitals try to monitor care to protect patients? They have almost universally adopted what they call "quality assurance" programs. But Dr. William Fifer, a Minneapolis hospital consultant, says "there is by and large no connection" between these programs and what the hospitals allow -- or forbid -- individual doctors to do. Hospitals now have the means, he says, to keep tabs on every doctor's competence and "adverse occurrences," and "base doctors' hospital privileges on their performances rather than their diplomas." They just don't do it.

One hospital administrator added: "With the DRGs and other pressures, we're not going to be very eager to get rid of a mediocre performer if he's also a good producer, a guy who admits lots of patients."

Dr. Stuart Shapiro, Philadelphia public health commissioner, says hospitals all over the country are "de-marketing" their services -- that is, turning patients away for lack of ability to pay or "demanding hundreds of dollars in deposits before they will allow the uninsured pregnant woman to get through the turnstiles of their clinic for prenatal care."

Expensive "heroic treatment" -- artificial organs, transplants, intensive care running into the hundreds of thousands of dollars for many Baby Does and Granny Does -- is "unfortunately now in the ascendancy," while fetal and infant deaths are on the increase in some inner cities, says Bailus Walker, Massachusetts health commissioner. Health insurors have begun financing expensive liver transplants for a few children, notes Dr. Howard Hiatt, former dean of the Harvard School of Public Health, while funds have been cut for inner city prenatal care.

The care of the poor -- measured by visits to doctors, among other statistics -- improved greatly during the 1960s and 1970s. But it never reached the level of the affluent in total quality and has again begun slipping, according to Bernard Tresnowski, current Blue Cross-Blue Shield president, and other authorities. "The health plight of the poor is becoming critical," say Drs. David and Pauline Rabin at Vanderbilt University in Nashville.

Thirty-five million Americans have no health insurance, and a Robert Wood Johnson Foundation study found 12 percent of the population have trouble getting medical care when they need it because of lack of finances. Many are sent to already over-burdened, under-financed public clinics or hospitals.

Dr. Paul Starr of Harvard, author of the acclaimed 1983 book "The Social Transformation of American Medicine," says we hear little about the people hospitals turn away because they "do their suffering in silence." He blames, in part, the distant executives of commercial hospital chains who "make decisions without looking into the eyes of grief and distress," running hospitals from afar only "to make a profit for stockholders."

Some investor-owned hospitals have indeed aroused local furors by turning away the indigent sick. But public hospital administrators in many cities report an increase in such "transfers" from commercial and nonprofit hospitals alike.

Investor-owned corporations now own or manage 1,493, or 21 percent, of the nation's 7,000 hospitals. Dr. Arnold Relman, editor of The New England Journal of Medicine, fears that "the commercial exploitation of health care" and the involvement of many physicians in commercial health enterprises will distort and do "major damage" to American medical care.

But Relman also believes "medical judgment, compassion and common sense are nowadays too often overruled by the economic concerns of hospital managers," commercial and noncommercial. He thinks all hospitals should be forbidden to transfer patients to public hospitals unless the move is medically necessary.

What about the patients of HMOs, the prepayment plans whose members get all their medical and hospital care from the plans' doctors? There are now nearly 350 such plans with 16.5 million members, compared with 72 with 4.4 million members just 13 years ago.

In the new era of medical competition and marketing and advertising, HMOs must now compete with each other, with private doctors and with health care corporations for patients. As they engage in price competition, they have to work harder to keep their costs low.

In the past few months health care professionals and medical faculty members -- highly sophisticated HMO participants -- have begun telling stories about being refused needed treatment or hospitalization by their cost-conscious HMOs.

A psychologist-member of an HMO told how his daughter, 19, phoned the HMO just after they joined to report "a bad pain in her back." She was told she could have an appointment in a week and meanwhile -- though no one at the HMO had ever seen her -- "we'll send you some medicine for the pain."

The young woman's mother insisted that she phone back and demand an emergency appointment. She did and was seen. She had a urinary tract infection that without doubt required immediate attention.

"They try to take care of too many patients with too small a staff," her father said. "That's what they call cost-control," another member said wryly.

"There's no question in my mind," comments Dr. Jack A. Meyer of the American Enterprise Institute, "but that a system structured with incentives to do less is in some cases not going to do enough."

On the other hand, he says -- of HMOs and cost controls and other reforms that seem to squeeze some patients too hard -- "We must ask, 'What if we don't make these changes?' We are groping today for a balance. If we don't put some restrictions on use of the system, I fear we'll have to do a lot worse. We'll see more people thrown off benefits or more rationing of care."

What about measures, meanwhile, to protect the patient from over-zealous cost-cutting?

"There are people thinking about safeguards," he says. "But not as much as I'd like."

There is much agreement, in short, among people who think about American health care on this final point. There is indeed need for more thought about the system's ultimate object: the too often forgotten patient.