Brain protection during retrograde cerebral perfusion-comparison between α-stat and pH-stat management

In order to compare the effect of acid base management on cerebral bleed flow and metabolism during retrograde cerebral perfusion (RCP), we have studied 79 blood gas samples in the α-stat and 16 ones in the pH-stat management from the patients undergoing aortic arch surgery. During retrograde cerebral perfusion at a nasopharyngeal temperature of 20°C, the pump flow was adjusted so that the pressure of the SVC would be maintained around 25 mmHg. In the pH-stat management, RCP flow rate was significantly greater and vascular resistance was significantly lower than those in the α- stat management. Lactic acid consumption, lactic and pyruvic acid rate and the glucose consumption showed no significant difference between groups. The pH-stat management revealed lower vascular resistance and greater RCP flow rate than did the α-stat management due to higher PaCO2 levels. The pH-stat management may have some efficacy for the brain circulation and the brain protection. However, the disadvantage of high PaCO2 levels has not been clarified. Further studies will be necessary to refine the standard for RCP management.