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Is there an association between release of protein S100B during cardiopulmonary bypass and memory disturbances?
Staffan Svenmarker1, Erik Sandström, Thomas Karlsson
1Department of Surgical & Perioperative Science, University of Umeå, Sweden. staffan.svenmarker.us@vll.se
Insights
High levels of protein S100B seven hours after cardiopulmonary bypass (CPB) correlate with explicit memory decline. Protein S100B levels during CPB do not predict memory issues, suggesting timing is crucial for its use as a brain injury marker.
Area of Science:
- Neuroscience
- Biomarkers
- Cardiovascular Surgery
Background:
- Protein S100B is a marker for brain cell injury.
- Its utility in conjunction with cardiopulmonary bypass (CPB) has been questioned.
- The relationship between S100B and memory disturbances requires further investigation.
Purpose of the Study:
- To investigate functional brain injury by examining the association between protein S100B levels and memory disturbances in patients undergoing coronary artery bypass grafting (CABG) with CPB.
- To determine the optimal timing for using S100B as a brain cell injury marker in the context of CPB.
Main Methods:
- A cohort of 415 low-risk patients undergoing CABG with CPB were studied.
- Protein S100B levels were measured during and at multiple time points after surgery.
- Explicit and implicit memory function were assessed preoperatively and at hospital discharge.
Main Results:
- Serum S100B levels peaked at the termination of CPB and gradually decreased over time.
- High S100B levels (>1.5 microg/l) at 7 hours post-CPB were significantly associated with a decline in explicit memory function (p = 0.006).
- No significant association was found between S100B levels at CPB termination and memory function decline (p = 0.834). Predictors of memory decline included S100B levels at 7 hours post-CPB, hospital length of stay, and neurological disorders.
Conclusions:
- Protein S100B levels measured 7 hours post-CPB, but not during CPB, are associated with explicit memory decline.
- These findings suggest that S100B should be used as a brain cell injury marker only several hours after surgery in the context of CPB.
- Timing of S100B measurement is critical for its accurate interpretation as a marker of brain injury following cardiac surgery.
Objective:
The use of protein S100B as a marker of brain cell injury in conjunction with cardiopulmonary bypass (CPB) has recently been questioned. The present study investigates functional brain injury based on the relation between S100B and memory disturbances.
Methods:
Four hundred and fifteen low-risk coronary artery bypass patients exposed to CPB were examined. The protein S100B was sampled during and after surgery. Explicit and implicit memory function was assessed preoperatively and at discharge from hospital. Possible associations between the release of the protein S100B and memory function were studied.
Results:
Serum concentration of S100B peaked at termination of CPB (0.895 +/- 0.84 microg/l) and decreased gradually; 7 h post CPB (0.436 +/- 0.59 microg/l), day 1 (0.149 +/- 0.27 microg/l) and day 2 (0.043 +/- 0.15 microg/l). High levels of S100B (>1.5 microg/l) 7 h post CPB were associated with a significant (-1 SD) decline of explicit memory function (p = 0.006); this was not seen at termination of CPB (p = 0.834). Predictors of memory decline were S100B 7 h post CPB, length of stay in hospital and concomitant neurological disorders. Postoperative S100B concentration was higher among patients with atrial fibrillation (p = 0.022).
Conclusion:
Only high levels of protein S100B found 7 h post CPB were associated with decline of explicit memory function, not the release seen during CPB. Thus, when using protein S100B, only values several hours remote from surgery should be used as a brain cell injury marker.