Influence of simulated prehospital transport, time to analysis and storage temperature on S100B values.

According to in-hospital guidelines, the biomarker S100B is used to rule-out intracranial lesions in mild-moderate head trauma. It is currently investigated if S100B is applicable in a prehospital setting. The aim was to compare S100B values and hemolysis index in blood samples drawn and stored under simulated prehospital conditions to standardized blood samples. 30 patients undergoing craniotomy at Department of Neurosurgery, Aarhus University Hospital each had six blood samples drawn. Two samples, drawn in in-hospital standardized Beckton Dickinson tubes and prehospital Monovette tubes respectively, were stored as references at 21 degrees C for 30 minutes. Two samples were stored at 15 and 29 degrees C respectively, one sample was stored at prolonged time (60 min) and one sample was transported for 30 min prior to centrifugation. S100B values were compared by equivalence test with a predefined equivalence margin of +/- 8.5%. There was no clinically relevant difference between samples stored in different tubes, at various temperatures or time to analysis compared to reference samples. Transported samples had a 11.5% [90% CI 6.55; 16.61] higher median S100B value and a 430% [95% CI 279.6; 661.4] higher median hemolysis index compared to reference samples. 3/30 (10%) patients had a S100B value above guideline cut-off in the transported sample which was not found in reference samples (false positive). There were no false negatives. In conclusion S100B values were not influenced by different tubes, temperatures and time to analysis. Transported samples had higher median S100B values and HIL index compared to reference samples.