Alene E. Downs is a frail but spirited 75-year-old woman who last March survived major heart surgery following more than 50 operations to remove leg tumors.

Since her last hospital stay, Downs rarely leaves her Silver Spring home. Neither does her daughter Lou Downs, who devotes all her time to caring for her mother. On the rare occasions Lou must go out, Alene said she feels imprisoned, afraid of injuring herself if she ventures out of bed. She broke both hips several years ago in a fall.

Both women realize how easily the elder Down's dependence could result in her becoming a burden on her daughter and two other grown children who live in the area.

That's a situation that Downs, who despite her infirmity possesses a quick wit, couldn't tolerate.

But thanks to a program called Lifeline, to begin in September at Washington Adventist Hospital in Takoma Park, Downs may be able to regain some degree of independence.

Lifeline offers the elderly and disable round-the-clock access to emergency medical services. For $10 a month, a transmitter and emergency call button can be installed in Down's home, and in the homes of others like her.

The Lifeline subscriber wears a call button with which to summon help. When the button is pressed, the unit sends a radio signal, triggering the transmitter, which sends a digital message through the phone line to the hospital, where it is printed out automatically.The system works via a remote-control telephone hookup, but the user need not be near the phone to send the distress signal.

According to hospital spokeswoman Geri Ann Fuller-Col, trained emergency room personnel will read the identifying code from the printed tape and look up the sender's medical and personal records on file at the hospital. Within minutes, appropriate help -- police, paramedics, a friend or a relative -- is sent to the caller's aide.

The Lifeline system can send an S.O.S. even if a person is unconscious. According to Lifeline literature, a timer, if not reset after a 12-hour interval, will automatically signal for help.

Lifeline was designed in 1975 by Andrew S. Dibner, a Boston university specialist in rehabilitation and gerontology, and was tested under a $64,000 federal grant. It is being used successfully at 141 hospitals in 29 states, according to Ross Trimby, vice president of sales for Lifeline Systems Inc., based in Waltham, Mass. The firm supplies all equipment and trains the hospital personnel who receive and respond to the messages.

Trimby said the system to be installed at the Takoma Park hospital will be the first in the Washington metropolitan area.

Money to purchase home units and install the equipment at the hospital are being raised by the Takoma Park Womens' Club Inc., an affiliate of the D.C. State Federation of Womens' Clubs. Ernestine Hersey, chairwoman of the fund-raising drive, said the club has raised the $6,000 needed for hospital equipment and another $1,800 to buy four home units, at $450 apiece. The club hopes to raise enough money to purchase 15 home units.

Hersey says the club chose Lifeline as its project because members felt it could help many elderly or severely disabled persons lead more secure and independent lives. With Lifeline, people such as Alene Downs might be able to remain at home rather than be forced to enter an institution. The system being installed at Washington Adventist can be connected to as many as 1,000 homes, according to Fuller-Col.

In some states, Trimby said, money designated to support institutional care for the elderly, handicapped or disabled instead is being used to establish Lifeline programs.

It costs an average of $70 a day to stay in a nursing home, Trimby said, compared with the small monthly fee charged for the Lifeline service.

Alene Downs is delighted at the prospect of becoming a Lifeline subscriber. "It will give us both (her and her daughter) the independence we need," she said.