Is there an association between release of protein S100B during cardiopulmonary bypass and memory disturbances?

Abstract

Objective-The use of protein S100B as a marker of brain cell injury in conjunction with cardiopulmonary bypass (CPB) has recently been questioned. The present study investigates functional brain injury based on the relation between S100B and memory disturbances. Methods-Four hundred and fifteen low-risk coronary artery bypass patients exposed to CPB were examined. The protein S100B was sampled during and after surgery. Explicit and implicit memory function was assessed preoperatively and at discharge from hospital. Possible associations between the release of the protein S100B and memory function were studied. Results-Serum concentration of S100B peaked at termination of CPB (0.895 ± 0.84 μg/l) and decreased gradually; 7 h post CPB (0.436 ± 0.59 μg/l), day 1 (0.149 ± 0.27 μg/l) and day 2 (0.043 ± 0.15 μg/l). High levels of S100B (> 1.5 μg/l) 7 h post CPB were associated with a significant (-1 SD) decline of explicit memory function (p = 0.006); this was not seen at termination of CPB (p = 0.834). Predictors of memory decline were S100B 7 h post CPB, length of stay in hospital and concomitant neurological disorders. Postoperative S100B concentration was higher among patients with atrial fibrillation (p = 0.022). Conclusion-Only high levels of protein S100B found 7 h post CPB were associated with decline of explicit memory function, not the release seen during CPB. Thus, when using protein S100B, only values several hours remote from surgery should be used as a brain cell injury marker.