War medicine is not a specialty taught to future doctors in America's medical schools. It should be, if the experiences last summer of Dr. Amal Shamma in a Beirut hospital mean anything.

Shamma, 38, is an American citizen of Lebanese descent whose medical training included studies at Duke University and Johns Hopkins. In 1974, she went to Beirut to practice. Last summer, during the Israeli reign of violence in Lebanon, she worked in the Berbir Hospital as the chief of emergency services.

Behind the dry biographical details is a physician of venturesome courage and supple mind. Her medical skills and her instinctive compassion during the battles must have seemed like blossoms pushing up through the sere rubble. What Shamma learned last summer about war medicine is also the seldom-told story about the link between the corpses and casualties and technology of killing that America exports in its role as the world's leading arms merchant.

During a long conversation with Shamma--she was visiting Washington on her way to see her mother and brother in Durham, N.C.--I was startled by a number of stories she told of last summer's devastation. But it was a set of statistics, in addition to the stories, that laid out, in consummate horror, the new boundaries of war.

During the civil war of 1976, 5 percent of those brought into Shamma's emergency room were dead on arrival. This summer, the number totaled 25 percent. In 1976, 15 percent of the wounded required admission for serious injury. In 1982, the number soared to more than 50 percent.

"The weapons used this summer," Shamma said, "were so much more effective in killing and maiming." It was a different enemy, one whose technique of killing had advanced far more than anyone's methods of healing. Recalling her and her staff's work, Shamma said that this was the first time they had heard of cluster munitions or phosphorous-tracing shells. "We had to learn how they kill and how these hurt. And how good they are and how ineffective we are. There's no way a doctor can compete with a soldier."

Shamma is anything but comfortable in talking about the part that weapons from the United States played in the gore she confronted daily in her emergency room. But the alternative is to turn away, to say with a straight face to herself and her dying patients that America means well, it's just that things like cluster munitions sometimes get out of hand.

Shamma tells of being at the hospital as an American while American products were tearing into the flesh of women, children and the elderly. "I felt not only bitterness but a great sense of guilt. I felt that I was responsible for every single person who was either killed or injured in that war."

Early in the war, Shamma thought that the death rate in her hospital was high because nurses and doctors were providing poor medical care. Then she realized the true cause: the care was excellent, but it couldn't match the efficiency of the weapons. One day, she recalled, "someone came to explain to us how fragmentation bombs manage to kill and mutilate so much. They explode in the air and spray down huge slivers of shrapnel so that even if you were hiding in a trench you would still be injured--and injured badly. You would be brought in minus a limb. Or decapitated. Or your body split open by these slivers like knives."

In mid-summer, the United States ceased shipment of cluster weapons to Israel, which, said a Pentagon spokesman, still had a stockpile. He added that the "U.S. government has responsibility, and is not happy."

The new weapons weren't the only traumas of the invasion. Gore became so routine that children were numbed by it. Once, Shamma remembers, a body was being carted into the hospital and the brain of the victim fell off the stretcher. No adult was emotionally strong enough to pick it up. Suddenly, "a young kid of 10 comes with two pieces of cardboard. He scoops it up and takes it into the morgue."

Shamma has yet to assess fully the impact of the war on her own life. Her hospital was bombarded into ruins. She will eventually return to Lebanon. Her goal now is to dispense some strong medicine to her fellow Americans: it was our weapons that helped level much of Beirut, and it is our responsiblity to join in the rebuilding of Lebanon. As unpleasant as that message is, she believes, correctly, it would be worse for us not to hear it.