title: Low serum S100beta protein levels following coronary artery surgery with or without cardiopulmonary bypass.
abstract: BACKGROUND
  S100beta protein has been used as a serum marker of brain injury during cardiac surgery. Previous studies may have been confounded by the re-transfusion of shed mediastinal blood, which has a high concentration of S100beta.
  
  
  OBJECTIVE
  To examine serum S100beta levels in coronary artery surgery patients in whom re-transfusion of shed mediastinal blood was avoided, and to compare levels with and without cardiopulmonary bypass (CPB).
  
  
  METHODS
  Serum S100beta levels were measured preoperatively, pre-heparin, post-protamine and 24 h postoperatively in 31 patients undergoing elective coronary artery surgery with (n = 14) or without (n = 17) CPB. The postoperative values were compared to their preoperative controls using two-tailed paired t-tests.
  
  
  RESULTS
  There was a minor increase in serum S100beta post-protamine in the CPB group only (0.41 ng/mL; P < 0.01). All other levels in both groups were within normal limits.
  
  
  CONCLUSIONS
  Coronary artery surgery without CPB is not associated with an increase in serum S100beta. The observed increase in the CPB group was four- to ninefold lower than levels previously reported. A possible explanation for the lower level was the avoidance of retransfusing shed mediastinal blood. If elevated S100beta levels are thought to represent a cerebral insult caused by CPB, the magnitude of the insult might be less than previously assumed.
authors.affiliation: Department of Anaesthesia, Sir Charles Gairdner Hospital Nedlands, Western Australia, Australia. nmg@cyllene.uwa.edu.au
authors.forename: N M
authors.initials: NM
authors.lastname: Gibbs
authors.forename: B D
authors.initials: BD
authors.lastname: Mahon
authors.forename: M A
authors.initials: MA
authors.lastname: Newman
authors.forename: A
authors.initials: A
authors.lastname: Prins
authors.forename: W M
authors.initials: WM
authors.lastname: Weightman