Many elderly and disabled patients are being shut out of nursing homes because a new restrictive Medicare payment system has prompted facilities to shun those with costly medical needs.

As a result, some patients are staying in hospitals much longer than necessary and others are being forced to enter nursing facilities far from their homes and families, according to hospital and nursing home personnel. For the frail and sick, that can mean greater isolation, emotional hardship and added risk of contracting hospital-borne infections.

Those who are increasingly unwelcome at skilled nursing facilities include patients requiring intravenous antibiotics, tube feeding, dialysis and ventilator support, according to hospital and nursing home personnel. Admitting those patients can be a sure way to lose money under Medicare's new, lower reimbursement rates, nursing home executives said.

The shift in payment methods, required by the Balanced Budget Act of 1997, is part of a federal effort to keep Medicare from collapsing under the financial burden imposed by the aging of the baby boomers. The cuts have had a variety of unpleasant trade-offs for patients, such as limiting their access to physical therapy and other rehabilitation services.

Hospitals and nursing homes have been lobbying hard for relief from the spending restraints, and it serves their interests to publicize such "unintended consequences."

The problem with nursing home admissions, which has yet to be quantified with any certainty, corresponds to the change in Medicare payment rates. The previous system was designed to reimburse facilities for the costs they incurred. The new system limits nursing homes to rates set by the government based on average industry costs for different types of care.

At a nursing home in Pennsauken, N.J., for example, it costs $268 a day to administer the intravenous antibiotic Zosyn to a patient admitted May 6, but Medicare pays only $177.36 a day. That leaves the nursing home $90.64 in the red before any other expenses are taken into account, according to Genesis Health Ventures Inc., the facility's parent company.

A year ago Medicare would have paid the Pennsauken nursing home $292 a day to cover the patient's room, board, nursing, and other basic expenses, Genesis said. Medicare also would have paid $67 per dose -- $268 a day -- to reimburse the facility for the expense of the antibiotic, Genesis said.

Though Genesis, a large nursing home company based in Kennett Square, Pa., says it is paying a heavy price to continue admitting expensive patients, some facilities are taking a different approach.

"The system has created certain types of patients who a nursing home will not admit," said Thomas Zwicker, who runs a Milwaukee nursing home.

Bernice A. Ptak, a 73-year-old widow and former factory worker, fits several of the categories. Having undergone treatment for cancer of the esophagus, she was admitted to a Delaware hospital May 13 when the feeding tube connected to her stomach began to leak.

She breathes through a surgical opening in her throat, which requires frequent clearing, and now receives her nutrition intravenously. She's also receiving Vancomycin, an expensive antibiotic of last resort, for a drug-resistant infection that her daughter says she contracted during a previous hospital stay.

Ptak no longer needs hospital care, and in past years it wouldn't have been difficult to transfer her to a nursing home, said Christine Pisano, a social worker at Christiana Hospital in Newark, Del. But Pisano struck out recently when she tried to find a bed for Ptak at any of 10 or so nursing homes.

"People basically laugh because they're just not going to take a complicated, expensive case like this," she said, referring to the responses she got when she called.

Unlike Ptak, Mildred Elnes of LaCrosse, Wis., found a nursing home bed -- but in Chippewa Falls, about 100 miles and two hours from her family. Elnes, who has heart problems, needs a ventilator to breathe. The LaCrosse hospital where she was being treated tried to transfer her to a nearby nursing home, but that facility recently stopped admitting ventilator patients.

Elnes's nephew, Kenneth Swanbeck, had been visiting her in the hospital once or twice a week, but he has only been able to see her once since she was moved to Chippewa Falls in March. The patient's 80-year-old sister hasn't been able to visit her at all. Alone at the nursing home, Elnes is scared and unable to communicate, Swanbeck said.

Faced with a similar dilemma in January, another elderly patient opted to remain in a LaCrosse hospital. He was finally discharged to a local nursing home more than three months later, when he no longer needed a ventilator.

At Suburban Hospital in Bethesda, it is becoming common for nursing homes to send representatives to screen patients, said Sharon George, the hospital's utilization and discharge manager. "If it turns out it will cost $600 a day to care for the patient and Medicare will only pay $400, then they're going to say no."

Federal regulations say health care providers such as nursing homes can be disqualified from Medicare if they employ a double standard to turn away Medicare patients while accepting others.

Yet it's tough to prove whether nursing homes are doing that, according to hospital workers who arrange nursing home placements. When rejecting Medicare patients, nursing homes typically say they don't have room, or that they lack the resources to meet a patient's needs. Some explain that they are making case-by-case calculations, hospital personnel said. In still other cases it's clear that the nursing homes aren't discriminating because they have stopped providing a particular service altogether.

The experience of Genesis Health Ventures underscores the trend. Genesis screens patients for other nursing home companies that use Genesis as a supplier of prescription drugs. The screening service is offered for any patient, "but Medicare patients are the ones we get all the calls on," Genesis spokeswoman Lisa Salamon said. As for patients with private insurance, "they're not going to screen those out because they can charge for that," Salamon said.

Since last July, the number of screenings has increased by a factor of 10, from 50 a week to 500 a week, Genesis chief executive Michael R. Walker said. "We know that most of those people that we do that analysis for are not being admitted," Walker said.

One Delaware nursing home has issued a more restrictive admissions policy for Medicare and non-Medicare patients alike. "With the new PPS [Medicare payment] guidelines in place, we can no longer accept the following type of patients," said the March notice from Parkview Nursing & Rehabilitation Center, which went on to list ventilator patients, heart patients on a dobutamine drip and six other categories.

Medicare payments are only half of the problem, said Stephen Silver, president of a company that manages Parkview. In a tight labor market, it is hard to maintain a staff capable of providing the more complex services, Silver said. Parkview makes exceptions to its new policy as staffing and workload permit, he added.

Until recently many nursing homes sought the types of patients they now avoid. The old Medicare payment system was a valuable source of revenue. But the system of cost reimbursement rewarded wasteful spending.

The financial incentives are being turned upside down. Last July Medicare began shifting toward a system of paying what it thinks the care should cost, based on nationwide data. For most nursing homes, the first stage of the transition began in January; for the remainder, it will begin this month..

In the 1980s the nation's hospitals went through a similar shift from cost-based Medicare reimbursements to capped payments. There was an outcry that hospitals were discharging patients "quicker and sicker," much like the later uproar over managed care's cost controls.

The nation's health care system "is going to have trouble going through this transition because they're used to a government that's sloppy," Health and Human Services Secretary Donna E. Shalala said in a recent appearance at the National Press Club.

The federal government's Health Care Financing Administration, which oversees Medicare, has asked the inspector general of the Department of Health and Human Services to assess beneficiaries' access to nursing homes. The study could help determine how widespread the problems are.

"In some cases, it may be appropriate for acutely ill patients to spend a little more time in a hospital before being transferred to a skilled nursing facility that may offer less intensive care," HCFA Administrator Nancy-Ann DeParle said in a statement.

The strict new nursing home admissions standards are a manifestation of the industry's financial distress. Several of the nation's largest nursing home chains are losing money and nursing home stocks have plummeted.

But hospitals seem to be complaining the loudest about nursing home admissions, because hospitals must absorb the expense of the Medicare patients stranded in their beds.

The ripple effects go beyond the federal health insurance program. When nursing homes stop offering services such as ventilator care and lay off the nurses who provide other specialized services, they leave fewer placement options for patients with private insurance.

At Christiana Hospital, dozens of patients are tying up beds while they wait for nursing home placements, making it harder to move other patients out of the emergency room or intensive care units, said Charles Smith, president of Christiana Care Corp., the parent company.

CAPTION: Bernice A. Ptak, 73, gets a kiss from her daughter Theresa Wintermantel at a hospital in Delaware. Because of strict Medicare payment rules, nursing homes had turned down requests to treat Ptak, who no longer needs hospital care.