As shown in this article about Children's Hospital in Boston heart-lung bypass machines are used as a way to allow tired organs to rest:

As he drove back to Children's in the dark, he ordered Jordan placed on a special heart-lung bypass machine that would give her heart a rest - and keep her alive - while doctors figured out what to do.

It was an emergency, and the cost - $3,600 a day - did not enter his mind. ''We try to do things as efficiently as we can,'' he said, ''but I am not prepared to cut corners in a life-and-death situation.''