Sarah Murnaghan, who suffers from severe cystic fibrosis, was receiving her new lungs Wednesday at Children's Hospital of Philadelphia, family spokeswoman Maureen Garrity said. Murnaghan's relatives were "beyond excited" about the development but were "keeping in mind that someone had to lose a family member and they're very aware of that and very appreciative," Garrity said.
No other details about the donor are known, including whether they came through the regular donor system or through public appeals.
Murnaghan's health was deteriorating when a judge intervened last week, giving her a chance at the much larger list of organs from adult donors.
"Some people would look at this and say it's evidence that if you get a PR campaign, a congressman and federal judge to pay attention, you're going to have far greater access to a transplant, but I don't think that's true," said ethicist Arthur Caplan of the NYU Langone Medical Center in New York of the Murnaghans' public stance.
The Newtown Square, Pa., family received word about the donor lungs Tuesday night, Garrity said. The surgery began just after 11:30 a.m. Wednesday and was expected to take at least six hours, she said.
Murnaghan's mother, Janet, said in a Facebook post that the family was "overwhelmed with emotions" and thanked all her supporters.
"Today is the start of Sarah's new beginning and new life!" she wrote, adding that the donor's family "has experienced a tremendous loss, may God grant them a peace that surpasses understanding."
During double lung transplants, surgeons must open up the patient's chest. Complications can include rejection of the new lung and infection.
Murnaghan's family and the family of another cystic fibrosis patient at the same hospital challenged existing transplant policy that made children under 12 wait for pediatric lungs to become available or be offered lungs donated by adults only after adolescents and adults on the waiting list had been considered. They said pediatric lungs are rarely donated.
On June 5, federal Judge Michael Baylson in Philadelphia ruled that Murnaghan and 11-year-old Javier Acosta of New York City should be eligible for adult lungs.
The Organ Procurement and Transplantation Network says 31 children under age 11 are on the waiting list for a lung transplant.
The network added Murnaghan to the adult waiting list after Baylson's ruling. Her transplant came just two days before a hearing was scheduled on the family's request for a broader injunction.
Critics warned there could be a downside to having judges intervene in the organ transplant system's established procedures. Lung transplants are difficult procedures and some say child patients tend to have more trouble with them than adults.
The national organization that manages organ transplants this week resisted making emergency rule changes for children under 12 who are waiting on lungs but created a special appeal and review system to hear such cases.
Caplan said Murnaghan's family "did have a legitimate complaint" about the rule that limited her access to adult lungs.
"When the transplant community met, they didn't want to change that rule without really thinking carefully about it," he said. The appeals process that was established this week was "built on evidence, not on influence."
He added: "In general, the road to a transplant is still to let the system decide who will do best with scarce, lifesaving organs. And it's important that people understand that money, visibility, being photogenic ... are factors that have to be kept to a minimum if we're going to get the best use out of the scarce supply of donated cadaver organs."
AP Science Writer Malcolm Ritter reported from New York
Copyright 2013 The Associated Press.