Time course of neurone-specific enolase and S-100 protein release during and after coronary artery bypass grafting

Serum neurone-specific enolase (NSE) and S-100 protein are well established as markers of cerebral injury, and have been used as markers of neuronal a nd glial cell damage, respectively, after cardiac surgery with cardiopulmon ary bypass (CPB), but the speed of their increase during CPB has not been s tudied. Therefore, we have investigated the time course of NSE and S-100 re lease during and after CPB. We studied 18 adult patients undergoing electiv e coronary artery bypass grafting (CABG). Standard hypothermic (32 degrees C) pulsatile bypass with membrane oxygenation was used. Blood samples were obtained at induction, before bypass, before rewarming, at the end of rewar ming, 10 min, 1 h and 8 h after bypass and 1, 2 and 3 days after surgery. N SE and S-100 were assayed using immunoradiometric assay kits (Sangtec Medic al). NSE and S-100 release followed similar time courses. Both increased sh arply during bypass, reached peak concentrations at the end of rewarming (m ean 25.55 (SEM 2.79) and 1.65 (0.23) mu g litre(-1), respectively), had dec reased significantly by the end of operation and returned to pre-bypass con centrations by the second day after surgery. No patient developed a major n eurological deficit. When using NSE and S-100 assays to study cerebral dysf unction in relation to CPB, postoperative samples miss peak (end-bypass) co ncentrations, and studies should be designed to include intraoperative samp les.