Total Prime of the Disc Oxygenator with Ringer's and Ringer's Lactate Solution for Cardiopulmonary Bypass

Clinical and Experimental Observations

¹ VA Hospital

Cardiopulmonary bypass can be safely performed in man for periods of two to three hours when the disc oxygenator with the Gebauer heat exchanger is primed with Ringer's or lactate Ringer's solution. At the moment it would appear that the latter may be the more physiologic perfusate in that the lactate compensates to a certain extent for the depletion in buffer base resultant from the decrease in oxygen-carrying capacity of the diluted blood. When a base deficit does occur, it can be compensated with infusion of sodium bicarbonate into the oxygenator.

Since metabolic acidosis is prone to occur with this technique, it would seem advantageous for the patient to have a buffer base excess and a high hematocrit prior to perfusion. Both in experimental animals, and in man, hypoxic acidosis was not as severe when the hematocrit was 45 to 50 per cent. In addition, hemodilution should be less than 60 ml./kg. body weight to avoid serious metabolic derangements.

The disadvantageous manifestations of this technique are more than compensated for by the fact that the patients are perfused with their own blood. Extraneous blood need be added to the pump oxygenator only when blood loss occurs or the flow rate becomes too low during prolonged bypass due to the gradual diffusion of the Ringer's into the tissues. In these instances it would seem expedient to add ACD blood containing heparin and calcium to the pump oxygenator rather than more Ringer's with further hemodilution.