Serum S-100 β protein during coronary artery bypass graft surgery with or without cardiopulmonary bypass

Background. Brain damage is a serious complication of cardiac anesthesia. The purpose of this study was to detect brain damage at different surgical stages during coronary artery bypass graft with or without cardiopulmonary bypass. Methods. We conducted a prospective, longitudinal study to evaluate serum S-100 β protein, an early marker of brain injury, in patients electively undergoing off-pump (n = 30) or traditional coronary artery bypass graft (n = 60). Blood was sampled immediately before anesthesia, before and after cardiopulmonary bypass, and on the day after surgery. Results. Serum S-100 β protein was lowest immediately before induction of anesthesia and significantly increased before and after cardiopulmonary bypass, then declined by the first postoperative day in both groups. Peak values were highest in the traditional group directly after coronary artery bypass graft. On the day after surgery, S-100 β protein levels were similar between groups, but were higher than baseline within each group. Significant increase in serum S-100 β protein was also observed even before cardiopulmonary bypass in cardiopulmonary bypass patients, or before manipulation of the heart and aorta in off-pump patients. These reflect the possibility that brain damage may occur before major manipulation (cardiopulmonary bypass or manipulating heart and aorta). Moreover, S-100 β levels did not return to normal on the day after the operation. Conclusions. This prospective study has shown that serum S-100 β protein was not only higher than baseline both after cardiopulmonary bypass and on the day after surgery in both groups of patients but it was also significantly increased before cardiopulmonary bypass or manipulation of the heart or aorta. These findings may have implications for anesthesiologic care during the total course of cardiac surgery.