BLOOD procurement for extracorporeal circuit priming has posed significant problems to workers in open-heart surgery. From the inception of this new surgical modality, attempts have been made to reduce or completely do away with the priming requirements of various pump oxygenators. In 1959, Panico7 developed a bubble oxygenator in which blood was not used as the priming material; instead physiologic saline was used. From his results and observations, there evolved the concept of hemodilution. Zuhdi,11 Roe,9 Cooley,2 DeWall,3 and Long5 used this technique with various perfusates as prime for the basic bubble oxygenators. Being initially a low-prime system, it was found readily adaptable to their purpose. Despite the large volume of perfusate necessary to prime a rotating disc oxygenator, it has been shown by Raison,8 Ablaza et al,1 Hellstrom,4 and recently Neville6 that hemodilution is also feasible with this type