The bad old days, when patients stared in agony at the clock on the hospital wall, waiting for the minutes to drag by so they could beg a nurse for more pain medication may, mercifully, be coming to an end.

Increasingly, hospitals are instituting pain relief programs in which patients, with proper safeguards against overdose or excessive use, can control their pain by dispensing medication when they feel they need it. The concept, patient controlled analgesia, or PCA, has become more and more popular in the past decade, as studies have shown that patients get greater relief -- and are more satisfied with their care -- when they control their own medication.

"PCA is more a philosophy than a major technical advance," said Michel Dubois, associate professor of anesthesiology at Georgetown University, which began using it two years ago. "Instead of a patient relying on a third party, he or she -- the best judge of his or her pain -- can exercise control."

Differing opinions about who should exercise control -- doctors or patients -- as well as fear of addiction and cultural attitudes toward pain that prize stoicism more than comfort have been impediments to patient-controlled pain relief, according to Dubois and others.

Dozens of studies have shown -- as a multitude of former patients can attest -- that at least 50 percent of postsurgical patients who receive injections from nurses to control pain are inadequately medicated. Other research has demonstrated that patients who control their own pain medication are more alert during the day, sleep better at night, recover more quickly and may require smaller doses of analgesics.

Patients also like it. A study of 80 women conducted by J. Stephen Naulty, associate professor of anesthesiology and obstetrics and gynecology at George Washington University Medical Center, has found that those in labor who self-administered an anesthetic were significantly more satisfied than their counterparts who received the same amount of medication from hospital staff in the traditional manner.

Safeguards that prevent accidental or deliberate overdose are built into PCA programs. Patients are typically permitted to administer medication on demand, within pre-set limits or at timed intervals by pushing a button.

The risk of addiction, according to experts including Paul F. White, an anesthesiologist at Washington University Medical Center, is minimal. Patients who take narcotics such as morphine to relieve pain are generally easily weaned after they recover.

Despite the proliferation of PCA programs, not all painkillers can be self-administered, including those given by intramuscular injection, which work more slowly. Doctors say they make decisions about whether to use PCA based on the nature of the pain and the needs of each patient.

Anesthesiologists at Georgetown, George Washington University Medical Center and Sibley Hospital, where PCA has been used for about two years, agree that giving patients such control has substantial payoffs. "Patients are asking for it," said George A. Morales, professor of anesthesiology at GW. "They know about it, and they like having more control."

Many patients report that controlling their own pain medication helps preserve their dignity at a time when they feel particularly vulnerable. "Even if pain scores are identical (when two methods of anesthesia are being compared)," said GW's Naulty, "patients just express more satisfaction."

PCA began in Victorian England, where, according to Dubois, women in labor were given a mask connected to an atomizer containing ether or chloroform. "It was self-limiting," he said, "because as soon as the woman became drowsy she dropped the mask." But PCA's modern incarnation began in 1968, when anesthesiologist Philip H. Sechzer, then of Baylor University, found that patients receiving on-demand analgesia experienced greater pain relief with smaller doses.

Part of the difficulty is calibrating how much medication is enough. As Washington University's White noted, "It is impossible to accurately predict how much pain a patient will experience after an operation, or how much analgesic medication will be required to provide adequate pain relief."

Naulty agreed. "Everyone's analgesic requirement is different," said Naulty. In his study using patient-controlled epidural anesthetic during labor, he found that women will administer anywhere from nothing to the maximum dose allowed. "We can't predict the infusion rate."

Children, too, are benefiting from the new philosophy of pain management. "It was apparent a number of years ago that the pain needs of children were not being met," said Willis McGill, chief of anesthesiology at Children's National Medical Center in Washington. Children's started a PCA program four years ago, at first available only to those older than 11, and it was later made available to those as young as 8. Decisions about which children should be included are based on emotional maturity.

Several months ago, McGill said, a program of parent-assisted analgesia was begun to meet the needs of younger children, whose parents are screened and trained by hospital staff. "Parents who are able to understand objective criteria of pain," such as crying, are administering analgesics to children as young as 5, he said.

The revolution in pain control has been rapid. Ten years ago, Dubois said, the belief that pain was an uncontrollable and necessary component of labor and delivery was common among physicians and women. "Now," he said, "a majority of women would not want to go through labor without an epidural," an anesthetic or pain killer injected near the spinal column.

The amount of medication required in an epidural is small compared to intravenous or intramuscular injections, and is mostly absorbed in the spinal column. Therefore, said Naulty, "an undetectable small amount reaches the baby." This eliminates the problem of fetal respiratory distress, which made doctors and women reluctant to use anesthesia to deal with labor pains.

Similarly, there have been significant advances in treating the pain associated with terminal cancer. By means of a spinal anesthetic that involves a lower dose than an epidural, and a small pump implanted in the abdomen, patients are sent home with a 21-day dose of pain-killing narcotics. Because the dose is so small, Morales said, "patients stay alert and pain is controlled better."

According to Dubois, "The only contraindications to PCA are the inability or the unwillingness of the patient to do it." But it seems in one case that few were unable or unwilling. In a 19-month study at the University of Washington at Seattle, 50 percent of patients were using PCA initially. By the end of the study, the figure had jumped to 87 percent.

Merle S. Goldberg is a freelance writer in Washington.