Dr. Hughes, who now lives in Vermont, says he suspected the call was a hoax. But he was able to verify it, and he called an attending pediatrician, Dr. James E. Drorbaugh, who promptly asked his patients to reschedule their appointments, left his office and jumped on a helicopter flight to the Otis hospital.

Dr. Drorbaugh — now in Hawaii — remembers being greeted by the president, who asked him to examine the baby. Finding Patrick in moderate distress, “with a rapid respiratory rate and grunting, with lots of effort going into each breath,” he advised transferring the infant to Boston.

The president asked if the Children’s Hospital facilities could be brought to the Cape, but Dr. Drorbaugh replied that they could not be.

Before leaving Otis, Dr. Drorbaugh said President Kennedy asked him to join him in wheeling the baby into the first lady’s room. She reached into the Isolette and held Patrick’s hand for about 10 minutes — the last time she would see him alive.

The baby was rushed back to Boston. In those days there were no neonatal I.C.U.’s, and ventilators, a standard therapy today, had yet to be used for premature babies. Moreover, it was August, and most of the senior physicians were on vacation, recalled a third doctor, Welton M. Gersony, then training in pediatric cardiology.

“The junior doctors felt overwhelmed and were desperate to get a senior person,” said Dr. Gersony, who later became chief of pediatric cardiology at what is now Morgan Stanley Children’s Hospital.

So the hospital called Dr. Gersony’s mentor, Dr. Alexander S. Nadas, a pioneer in pediatric cardiology, who arrived the next day, Thursday, Aug. 8, from Cape Cod. Patrick’s breathing had become even more labored and Dr. Nadas said, “Welton, we go see the president” — his Hungarian accent turning the w’s into v’s.