The invention of the DeWall Bubble Oxygenator, a heart-lung machine, was received with great interest by heart surgeons from all over the world. C. Walton Lillehei repeatedly received requests by staff of other medical institutions to visit the University Medical Center in order to observe the oxygenator in operation and to witness the techniques utilized to repair congenital heart defects on the open heart. 

Many of the visiting surgeons returned to their own medical centers to implement use of the DeWall Bubble Oxygenator and the surgical practices witnessed at the University of Minnesota.