1.   But the heart is now beating strongly in Sean and his lungs are working well, Copeland said.

2.   In a final move, doctors took his father off the respirator with the idea that his lungs would not work on their own if kept on a respirator.

3.   Low air pressure makes your heart and lungs work harder.

4.   This means your lungs must work harder to extract the available oxygen.

5.   It is based on the idea that smaller, but healthier lungs can work better after the operation.