Serial measurement of serum S-100B protein as a marker of cerebral damage after cardiac surgery

Background We used serial measurements of serum S-100B protein to evaluate the time course of serum S-100B protein concentration after cardiovascular surgery and to determine the clinical relevance of its concentration and cerebral damage. Methods We assessed neurologic function in 149 patients undergoing cardiovascular surgery with cardiopulmonary bypass. The patients were classified into three groups according to their early postoperative outcome: those without complications (group A), those having unconsciousness or convulsion or both but no hemiplegia (group B), and those having unconsciousness and hemiplegia either with or without convulsion (group C). Serum S-100B protein concentrations were measured with a commercially available immunoluminometric assay, Sangtec 100 LIA, at seven time-points: before cardiopulmonary bypass, at the end of cardiopulmonary bypass, and at 5, 12, 24, 48, and 72 hours after cardiopulmonary bypass. Results At 5 hours after cardiopulmonary bypass, the S-100B values in groups B and C were significantly higher than the value in group A. Although the S-100B level decreased in group C during the first 5 hours after cardiopulmonary bypass, it increased thereafter (12 through 24 hours) and continued at a high level until the final measurement at 72 hours. At 12 hours after cardiopulmonary bypass, S-100B was significantly higher in group C than in group B. This late increase in S-100B was associated with radiologically detected abnormalities and cerebral damage. Conclusions Serial measurement of serum S-100B protein in the initial 12 hours after cardiopulmonary bypass can be used to predict early postoperative brain injury.