Okayama University Hospital said Wednesday it had succeeded in transplanting parts of a mother’s left lung into her 2-year-old son, who became Japan’s youngest ever recipient of a lung transplant.

It was also a global first for surgery involving the cutting of a human lung into the smallest possible viable size, the hospital said.

“We can now save young children previously unable to have transplant surgery because they were too small,” said Takahiro Oto, whose team led the operation.

Oto, an associate professor of respiratory surgery at the state-run Okayama University, said surgeons operated on the boy, aged 2 years and 9 months, on Aug. 31. An artificial respirator was removed on Sept. 13, whereupon the boy resumed breathing on his own, the surgeon said.

The mother and boy are residents of Saitama Prefecture, north of Tokyo.

In late April, the boy contracted idiopathic interstitial pneumonia, which resulted in lung failure. He was hospitalized at the Saitama Children’s Medical Center the following month.

Medical checks showed that the boy could only receive tissue from his mother’s lungs. The hospital decided to take the left lower lobe of the mother’s lung, cutting it down to a viable size.

In mid-August the boy’s condition worsened due to a shortage of oxygen, and a Self-Defense Forces plane flew the boy to Okayama on Aug. 29.

In July 2013, Okayama University Hospital succeeded in removing the right middle lobe of another woman’s lung and transplanting it into her 3-year-old son, which was the first time that such surgery had been carried out successfully anywhere in the world.