Comparison of Alpha-Stat and pH-Stat Cardiopulmonary Bypass in Relation to Jugular Venous Oxygen Saturation and Cerebral Glucose-Oxygen Utilization

Abstract

Jugular venous oxygen saturation (SJVo2) reflects the balance between cerebral blood flow and metabolism. This study was designed to compare the effects of two different acid-base strategies on jugular venous desaturation (SJVo2 <50%) and cerebral arteriovenous oxygen-glucose use. We performed a prospective, randomized study in 52 patients undergoing cardiopulmonary bypass (CPB) at 27°C with either alpha-stat (n = 26) or pH-stat (n = 26) management. A retrograde internal jugular vein catheter was inserted, and blood samples were obtained at intervals during CPB. There were no differences in preoperative variables between the groups. SJVo2 was significantly higher in the pH-stat group (at 30 min CPB: 86.2% ± 6.1% versus 70.6% ± 9.3%;P < 0.001). The differences in arteriovenous oxygen and glucose were smaller in the pH-stat group (at 30 min CPB: 1.9 ± 0.82 mL/dL versus 3.98 ± 1.12 mL/dL;P < 0.001; and 3.67 ± 2.8 mL/dL versus 10.1 ± 5.2 mL/dL;P < 0.001, respectively). All episodes of desaturation occurred during rewarming, and the difference in the incidence of desaturation between the two groups was not significant. All patients left the hospital in good condition. Compared with alpha-stat, the pH-stat strategy promotes an increase in SJVo2 and a decrease in arteriovenous oxygen and arteriovenous glucose differences. These findings indicate an increased cerebral supply with pH-stat; however, this strategy does not eliminate jugular venous desaturation during CPB.