Delayed rises in serum S100B levels and adverse neurological outcome in infants and children undergoing cardiopulmonary bypass.

BACKGROUND: The protein S100B is a marker of brain injury. Early after cardiopulmonary bypass (CPB), serum S100B levels are artefactually high. We investigated whether delayed (48 h) rise in S100B levels may have a role in detecting brain injury after CPB.
METHODS: Data from 43 children were analysed in this study. Samples were collected at preincision and 30 min, 24 and 48 h postbypass and then analysed by using a commercially available radioimmunoassay (Sangtec100). Charts were reviewed at 3-5 months for evidence of neurological injury.
RESULTS: S100B levels were high preoperatively in neonates and universally high immediately postbypass. In 36 children, samples were available for all time points. Compared with preoperative levels, rises occurred at both 24 and 48 h in three patients, only at 24 h in four patients and only at 48 h in three patients. Two patients had evidence of neurological injury. A rise at 48 h was associated with neurological injury (odds ratio 33.9, P < 0.03, 95% CI 1.39-827). There was no association between neurological injury and S100B levels at 24 h. Both the patients with neurological injury had rises at 48 h that were significantly higher than patients with rises at 48 h without injury.
CONCLUSIONS: The results of this study suggest that monitoring S100B levels in the late postoperative period may still have a role in detecting neurological injury after cardiac surgery in children. Consistent with previous observations, S100B is high preoperatively in neonates and early postbypass in all patients.