ST. LOUIS -- Lung transplant surgeons at Washington University in St. Louis reached, then surpassed, a milestone this week.

They performed the 1,000th adult lung transplant at Barnes-Jewish Hospital on Wednesday, then did another one just a few hours later.

That's not counting almost 400 lung transplants they performed at St. Louis Children's Hospital next door, according to the surgeons.

The Washington University Medical Center, consisting of Barnes-Jewish, Children's Hospital, and the Washington University School of Medicine, said it's the busiest lung transplant center in the U.S., drawing patients from around the world.

It said it also surpasses national averages in outcomes.

The 1,000th patient is a 28-year-old man from Indiana who has cystic fibrosis and had been on the lung transplant list since November.

The 1,001st patient is a 63-year-old man from Arkansas who suffered from pulmonary fibrosis and had been on the waiting list for 54 days. He moved to St. Louis the day after Thanksgiving to be near the hospital.

Both men were listed in serious condition, but that's normal after a transplant, Barnes-Jewish spokeswoman Kathryn Holleman said. They're both expected to move out of the intensive care unit soon. After discharge in about two weeks, they'll stay in St. Louis for three months so their conditions and medications can be monitored.

The medical center's lung transplant program was started in 1988 by a team that innovated and developed surgical techniques that it says are acknowledged as the gold standard.

The University of Pennsylvania Medical Center has done slightly more adult lung transplants, but fewer children's lung transplants, Holleman said.