Serum S100B and hypothermic circulatory arrest in adults

Effect of intravenous versus inhaled anesthetics on blood-brain barrier dysfunction and neuroinflammation in elderly patients undergoing major surgery: study protocol of a randomized controlled trial

BACKGROUND

Postoperative cognitive dysfunction (POCD) is one of the major complications after surgery, with devastating clinical outcomes. Although POCD is a condition with a multifactorial pathophysiology, blood-brain barrier (BBB) dysfunction and neuronal injury have been shown to play a critical role, especially in the elderly. Previous studies have demonstrated that the choice of anesthetics affect BBB permeability and neuroinflammation. However, most studies are carried out on animals, with limited research undertaken on humans. Therefore, we will compare the effect of intravenous anesthetics and inhaled anesthetics on BBB dysfunction and the change of inflammatory markers after surgery.

METHODS

One hundred and fifty-four patients who are 60 years of age or older undergoing major surgery for more than 2 h will be randomly allocated to two anesthetics groups (intravenous, inhaled) in a 1:1 ratio. In the intravenous anesthetics group (group P), propofol will be infused with a target-controlled infusion (TCI) system throughout the entire surgery. In the inhaled anesthetics group (group G), bolus injection of propofol will be administered for loss of consciousness, and simultaneously sevoflurane will be initiated for the maintenance of anesthesia. The primary outcome is the change in serum S100 calcium binding protein β (S100β) at four time points: before induction of anesthesia, at the end of surgery, 4 h after surgery, postoperative day 1. Secondary outcomes include changes in the inflammatory markers, serum interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α, and C-reactive protein; the incidence of delirium; and the change in the cognitive function between groups. In patients pre-scheduled for postoperative intensive care unit admission, the cerebrospinal fluid/serum albumin quotient (Qalb) between the two groups will be compared before and after surgery, and change in inflammatory markers in serum and CSF will be analyzed in relation to the Qalb.

DISCUSSION

The current study will compare the effect of intravenous versus inhaled anesthetics on blood-brain barrier permeability and, as a result, the difference in neuroinflammation in elderly patients. Also, the study results will provide additional information to develop intraoperative anesthetic strategies to reduce POCD.

TRIAL REGISTRATION

The trial was prospectively registered at Clinical Trials protocol registration with identifier 2310-117-126 on April 9, 2024.

S100B, Actor and Biomarker of Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) accounts for approximately 80% of all TBI cases and is a growing source of morbidity and mortality worldwide. To improve the management of children and adults with mTBI, a series of candidate biomarkers have been investigated in recent years. In this context, the measurement of blood biomarkers in the acute phase after a traumatic event helps reduce unnecessary CT scans and hospitalizations. In athletes, improved management of sports-related concussions is also sought to ensure athletes' safety. S100B protein has emerged as the most widely studied and used biomarker for clinical decision making in patients with mTBI. In addition to its use as a diagnostic biomarker, S100B plays an active role in the molecular pathogenic processes accompanying acute brain injury. This review describes S100B protein as a diagnostic tool as well as a potential therapeutic target in patients with mTBI.

The Ca2+-Binding S100B Protein: An Important Diagnostic and Prognostic Neurobiomarker in Pediatric Laboratory Medicine

In recent decades a significant scientific effort has focused on projects regarding the use of neurobiomarkers in perinatal medicine with a view to understanding the mechanisms that interfere with physiological patterns of brain development and lead to ominous effects in several human diseases. Numerous potential neurobiomarkers have been proposed for use in monitoring high-risk fetuses and newborns, including markers of oxidative stress, neuroproteins, and vasoactive agents. Nonetheless, the use of these markers in clinical practice remains a matter of debate. Recently, the calcium-binding S100B protein has been proposed as being an ideal neurobiomarker, thanks to its simple availability and easy reproducibility, to the possibility of detecting it noninvasively in biological fluids with good reproducibility, and to the possibility of a longitudinal evaluation in relation to reference curves. The present chapter contains an overview of the most significant studies on the assessment of S100B in different biological fluids as a trophic factor and/or marker of brain damage in high-risk fetuses and newborns.

Biomarkers in traumatic brain injury (TBI): a review

Biomarkers can be broadly defined as qualitative or quantitative measurements that convey information on the physiopathological state of a subject at a certain time point or disease state. Biomarkers can indicate health, pathology, or response to treatment, including unwanted side effects. When used as outcomes in clinical trials, biomarkers act as surrogates or substitutes for clinically meaningful endpoints. Biomarkers of disease can be diagnostic (the identification of the nature and cause of a condition) or prognostic (predicting the likelihood of a person's survival or outcome of a disease). In addition, genetic biomarkers can be used to quantify the risk of developing a certain disease. In the specific case of traumatic brain injury, surrogate blood biomarkers of imaging can improve the standard of care and reduce the costs of diagnosis. In addition, a prognostic role for biomarkers has been suggested in the case of post-traumatic epilepsy. Given the extensive literature on clinical biomarkers, we will focus herein on biomarkers which are present in peripheral body fluids such as saliva and blood. In particular, blood biomarkers, such as glial fibrillary acidic protein and salivary/blood S100B, will be discussed together with the use of nucleic acids (eg, DNA) collected from peripheral cells.

S100 and S100β: biomarkers of cerebral damage in cardiac surgery with or without the use of cardiopulmonary bypass

OBJECTIVE

The present study is to describe the clinical impact of S100 and S100β for the evaluation of cerebral damage in cardiac surgery with or without the use of cardiopulmonary bypass (CPB).

METHODS

Quantitative results of S100 and S100β reported in the literature of the year range 1990-2014 were collected, screened and analyzed.

RESULTS

Cerebrospinal fluid and serum S100 levels showed a same trend reaching a peak at the end of CPB. The cerebrospinal fluid/serum S100 ratio decreased during CPB, reached a nadir at 6 h after CPB and then increased and kept high untill 24 h after CPB. Serum S100 at the end of CPB was much higher in infant than in adults, and in on-pump than in off-pump coronary artery bypass patients. ∆S100 increased with age and CPB time but lack of statistical significances. Patients receiving an aorta replacement had a much higher ∆S100 than those receiving a congenital heart defect repair. Serum S100β reached a peak at the end of CPB, whereas cerebrospinal fluid S100 continued to increase and reached a peak at 6 h after CPB. The cerebrospinal fluid/serum S100β ratio decreased during CPB, increased at the end of CPB, peaked 1 h after CPB, and then decreased abruptly. The increase of serum S100β at the end of CPB was associated with type of operation, younger age, lower core temperature and cerebral damages. ∆S100β displayed a decreasing trend with age, type of operation, shortening of CPB duration, increasing core temperature, lessening severity of cerebral damage and the application of intervenes. Linear correlation analysis revealed that serum S100β concentration at the end of CPB correlated closely with CPB duration.

CONCLUSION

S100 and S100β in cerebrospinal fluid can be more accurate than in the serum for the evaluations of cerebral damage in cardiac surgery. However, cerebrospinal fluid biopsies are limited. But serum S100β and ∆S100β seem to be more sensitive than serum S100 and ∆S100. The cerebral damage in cardiac surgery might be associated with younger age, lower core temperature and longer CPB duration during the operation. Effective intervenes with modified CPB circuit filters or oxygenators and supplemented anesthetic agents or priming components may alleviate the cerebral damage.

Modeling serum level of s100β and bispectral index to predict outcome after cardiac arrest

OBJECTIVES

This study was designed to evaluate multimodal prognostication in patients after cardiac arrest (CA).

BACKGROUND

Accurate methods to predict outcome after CA are lacking.

METHODS

Seventy-five patients with CA treated with therapeutic hypothermia after cardiac resuscitation were enrolled in this prospective observational study. Serum levels of neuron-specific enolase (NSE) and neuron-enriched S100 beta (S100β) were measured 48 h after CA. Bispectral index (BIS) was continuously monitored during the first 48 h after CA. The primary endpoint was neurological outcome, as defined by the cerebral performance category (CPC) at 6-month follow-up: scores 1 or 2 indicated good outcome, and scores 3 to 5, poor outcome. The secondary endpoint was survival.

RESULTS

A total of 46 (61%) patients survived at 6 months and 41 (55%) patients had CPC 1 or 2. Levels of NSE and S100β were higher in patients with poor outcomes compared with patients with good outcomes (4-fold and 10-fold, respectively; p < 0.001). BIS was lower in patients with poor outcomes (10-fold; p < 0.001). NSE, S100β, or BIS alone predicted neurological outcome, with areas under the receiver-operating characteristic curve (AUC) above 0.80. Combined determination of S100β and BIS had an incremental predictive value (AUC: 0.95). S100β improved discriminations based on BIS (p = 0.0008), and BIS improved discriminations based on S100β (p < 10(-5)). Patients with S100β level above 0.03 μg/l and BIS below 5.5 had a 3.6-fold higher risk of poor neurological outcome (p < 0.0001). S100β and BIS predicted 6-month mortality (log-rank statistic: 50.41; p < 0.001).

CONCLUSIONS

Combined determination of serum level of S100β and BIS monitoring accurately predicts outcome after CA.

Neurological biomarkers in the perioperative period

The rapid detection and evaluation of patients presenting with perioperative neurological dysfunction is of great clinical relevance. Biomarkers have been defined as biological molecules that can be used as an indicator of new onset or progression of a biological process or effect of treatment. Biomarkers have become increasingly important in this setting to supplement other modalities of diagnosis such as EEG, sensory- or motor-evoked potential, transcranial Doppler, near-infrared spectroscopy, or imaging methods. A number of neuro-proteins have been identified and are currently under investigation for potential to provide insights into injury severity, outcome, and the ability to monitor cellular damage and molecular events that occur during neurological injury. S100B is a protein released by glial cells and is considered a marker of blood-brain barrier dysfunction. Clinical studies in patients undergoing cardiac and non-cardiac surgery indicate that serum levels of S100B are increased intraoperatively and after operation. The neurone-specific enolase has also been extensively investigated as a potential marker of neuronal injury in the context of cardiac and non-cardiac surgery. A third biomarker of interest is the Tau protein, which has been linked to neurodegenerative disorders. Tau appears to be more specific than the previous two biomarkers since it is only found in the central nervous system. The metalloproteinase and ubiquitin C terminal hydroxylase-L1 (UCH-L1) are the most recently researched markers; however, their usefulness is still unclear. This review presents a comprehensive overview of S100B, neuronal-specific enolase, metalloproteinases, and UCH-L1 in the perioperative period.

Arterio-jugular Differences in Serum S-100β Proteins in Patients Receiving Selective Cerebral Perfusion

PURPOSE

The early increase in serum S100beta after cardiopulmonary bypass (CPB) seems to be derived from an extracerebral source. To exclude contamination, we investigated the arterio-jugular differences in S100beta levels in patients receiving selective cerebral perfusion (SCP). We also evaluated the brain-protective effect of SCP by comparing the arterial S100beta levels with those in patients undergoing coronary artery bypass grafting (CABG).

METHODS

We measured arterial and jugular venous levels of S100beta in ten patients undergoing aortic arch repair with SCP for up to 12 h postoperatively (SCP group). We also measured arterial levels of S100beta in nine patients undergoing CABG (CPB group).

RESULTS

There was no incidence of hospital death or stroke. The arterial levels of S100beta in both groups were comparable and peaked just after the conclusion of CPB. The arterial and jugular venous levels of S100beta were almost equivalent. The arterio-jugular differences in S100beta levels were negligible, even in our SCP-group patient with postoperative delirium, who had a peak value three times higher than the other patients.

CONCLUSIONS

The arterio-jugular differences in S100beta did not clarify the origin of their increase. Thus, measuring the jugular venous levels of S100beta in patients without postoperative clinical neurological deterioration would be of little benefit. However, SCP seems to protect the brain against S100beta release as effectively as conventional CPB.

Biochemical markers of brain injury: could they be used as diagnostic adjuncts in cases of inflicted traumatic brain injury?

Child abuse is the leading cause of serious traumatic brain injury (TBI) in infants and young children (Billmire & Myers, 1985; Bruce & Zimmerman, 1989). The incidence of serious or fatal inflicted traumatic brain injury (iTBI) in children < 1 year of age is approximately 1 in 3,300 ( Keenan et al., 2003); since many cases of iTBI are of mild or moderate severity, the incidence is probably significantly higher. Even at an incidence of 1 in 3,300, iTBI is as common as the incidence of cystic fibrosis (CF), the most common genetic recessive disease in the Caucasian population. Proper diagnosis of iTBI is difficult even for experienced and astute physicians because its presentation can be subtle and important historical data are often lacking. As a result, misdiagnosis is common and can have catastrophic medical consequences for patients and significant financial consequences for society ( Ewing-Cobbs et al., 1998; Jenny, Hymel, Pitzen, Reinert, & Hay, 1999). Unlike CF for which there are several well established screening tests, there are currently no diagnostic adjuncts to help physicians screen for possible iTBI.

Neuron-specific enolase and S100B in cerebrospinal fluid after severe traumatic brain injury in infants and children

BACKGROUND

Traumatic brain injury (TBI) is a leading cause of death and disability in children. Considerable insight into the mechanisms involved in secondary injury after TBI has resulted from analysis of ventricular cerebrospinal fluid (CSF) obtained in children with severe noninflicted and inflicted TBI (nTBI and iTBI, respectively). Neuron-specific enolase (NSE) is a glycolytic enzyme that is localized primarily to the neuronal cytoplasm. S100B is a calcium-binding protein localized to astroglial cells. In adults, CSF and serum concentrations of NSE and S100B have served as markers of neuronal damage after TBI. Neither NSE nor S100B has previously been studied in CSF after TBI in infants or children.

OBJECTIVE

To compare the time course and magnitude of neuronal and astroglial death after nTBI and iTBI by measuring CSF concentrations of NSE and S100B using a rapid enzyme-linked immunosorbent assay.

METHODS

Severe nTBI and iTBI were defined by strict clinical criteria. Serial ventricular CSF samples (n = 35) were obtained from children 1.5 to 9 years with severe nTBI (n = 5) and children 0.2 to 1.5 years (n = 5) with severe iTBI. Lumbar CSF samples from 5 children 0.1 to 2.3 years evaluated for meningitis were used as a comparison group. CSF NSE and S100B concentrations were quantified by an enzyme-linked immunosorbent assay (SynX Pharma Inc, Ontario, Canada).

RESULTS

There was no difference in age between patients with iTBI (median [range]: 0.2 years [0.2-1.8]), nTBI (2.0 years [1.5-9]), and the comparison group (0.2 years [0.2-1.8]). The initial Glasgow Coma Scale score was higher in the iTBI group (9 [4-14]) versus the nTBI group (3 [3-7]). NSE was increased in TBI versus the comparison group in 34 of 35 samples. Mean NSE was markedly increased (mean +/- SEM, 117.1 +/- 12.0 ng/mL vs 3.5 +/- 1.4 ng/mL). After nTBI, a transient peak in NSE was seen at a median of 11 hours after injury (range: 5-20 hours). After iTBI, an increase in admission NSE was followed by a sustained and delayed peak at a median of 63 hours after injury (range: 7-94). The magnitude of peak NSE was similar in nTBI and iTBI. S100B was increased versus the comparison group in 35 of 35 samples. Mean S100B was markedly increased in TBI versus the comparison group (1.67 +/- 0.2 ng/mL vs 0.02 +/- 0.0 ng/mL). S100B showed a single peak at 27 hours (range: 5-63 hours) after both nTBI and iTBI. The mean S100B concentration, peak S100B concentration, and the time to peak were not associated with mechanism of injury.

CONCLUSIONS

Markers of neuronal and astroglial death are markedly increased in CSF after severe nTBI and iTBI. ITBI produces a unique time course of NSE, characterized by both an early and late peak, presumably representing 2 waves of neuronal death, the second of which may represent apoptosis. Delayed neuronal death may represent an important therapeutic target in iTBI. NSE and S100B may also be useful as markers to identify occult iTBI, help differentiate nTBI and iTBI, and assist in determining the time of injury in cases of iTBI.

Neurological and cognitive disorders after coronary artery bypass grafting

Cerebral injury is a major cause of mortality and morbidity of coronary artery bypass grafting. Stroke occurs in 3% of patients and is largely caused by embolization of atheromatous debris during manipulation of the diseased aorta. Cognitive impairment, which is predominantly caused by microembolization of gaseous and particulate matter, mainly generated by cardiotomy suction, is more common. Demonstration of similar cognitive impairment in patients operated on without cardiopulmonary bypass indicates that other pathophysiological mechanisms, such as anaesthesia and hypoperfusion, are also involved. Advances in medical, anesthetic, and surgical management have resulted in a reduction in the incidence of neurological injury in CABG patients over the past decade. On the other hand, an increasingly elderly population with more severe comorbidity, who are more prone to cerebral injury, are increasingly being referred for CABG. Possible mechanisms to reduce overt and subtle cerebral injury are discussed. The use of composite arterial grafts performed on the beating heart may be the most effective way of minimizing the risk of cerebral injury associated with CABG.

S100beta correlates with neurologic complications after aortic operation using circulatory arrest

BACKGROUND

Astrocyte protein S100beta is a potential serum marker for neurologic injury. The goals of this study were to determine whether elevated serum S100beta correlates with neurologic complications in patients requiring hypothermic circulatory arrest (HCA) during thoracic aortic repair, and to determine the impact of retrograde cerebral perfusion (RCP) on S100beta release in this setting.

METHODS

Thirty-nine consecutive patients underwent thoracic aortic repairs during HCA; RCP was used in 25 patients. Serum S100beta was measured preoperatively, after cardiopulmonary bypass, and 24 hours postoperatively.

RESULTS

Neurologic complications occurred in 3 patients (8%). These patients had higher postbypass S100beta levels (7.17 +/- 1.01 microg/L) than those without neurologic complications (3.63 +/- 2.31 microg/L, p = 0.013). Patients with S100beta levels of 6.0 microg/L or more had a higher incidence of neurologic complications (3 of 7, 43%) compared with those who had levels less than 6.0 microg/L (0 of 30, p = 0.005). Retrograde cerebral perfusion did not affect S100beta release.

CONCLUSIONS

Serum S100beta levels of 6.0 microg/L or higher after HCA correlates with postoperative neurologic complications. Using serum S100beta as a marker for brain injury, RCP does not provide improved cerebral protection over HCA alone.

Serum S-100beta protein predicts brain injury after hypothermic circulatory arrest in pigs

OBJECTIVE

Serum S-100beta protein is suggested to be a neurobiochemical marker of brain injury after cardiac and aortic arch surgery. The aim of the present study was to investigate the predictive value of S-100beta protein with respect to histopathological analysis of the brain after a prolonged period of hypothermic circulatory arrest (HCA).

METHODS

Eighteen pigs (21 to 31 kg) underwent a 75 min period of HCA at 20 degrees C. Serum concentrations of S-100beta were assayed in mixed venous blood before and 2, 4, 7 and 20 h after HCA. A semiquantitative post-mortem histopathological analysis scoring all main regions of the brain was carried out in every animal.

RESULTS

All animals were stable during and after cardiopulmonary bypass (CPB) and survived at least to the first postoperative day. Ten of the 18 animals survived 7 days after surgery and were electively sacrificed. Animals with severe histopathological injury showed higher serum S-100beta protein levels at every time point after HCA. The strongest correlation between the total histopathologic score and serum S-100beta levels was found at 7 h after HCA (tau = 0.422 and p = 0.023).

CONCLUSION

Serum S-100beta protein levels correlate with histopathological injury after a prolonged period of HCA in pigs. This finding supports the results of previous studies suggesting the potential accuracy of S-100beta in the prediction of brain injury after cardiac surgery.

Leukocyte filtration improves brain protection after a prolonged period of hypothermic circulatory arrest: A study in a chronic porcine model

BACKGROUND

Ischemic cerebral injury follows a well-attested sequence of events, including 3 phases: depolarization, biochemical cascade, and reperfusion injury. Leukocyte infiltration and cytokine-mediated inflammatory reaction are known to play a pivotal role in the reperfusion phase. These events exacerbate the brain injury by impairing the normal microvascular perfusion and through the release of cytotoxic enzymes. The aim of the present study was to determine whether a leukocyte-depleting filter (LeukoGuard LG6, Pall Biomedical, Portsmouth, United Kingdom) could improve the cerebral outcome after hypothermic circulatory arrest.

METHODS

Twenty pigs (23-30 kg) were randomly assigned to undergo cardiopulmonary bypass with or without a leukocyte-depleting filter before and after a 75-minute period of hypothermic circulatory arrest at 20 degrees C. Electroencephalographic recovery, S-100beta protein levels, and cytokine levels (interleukin 1beta, interleukin 8, and tumor necrosis factor alpha) were recorded up to the first postoperative day. Postoperatively, all animals were evaluated daily until death or until electively being put to death on day 7 by using a quantitative behavioral score. A postmortem histologic analysis of the brain was carried out on all animals.

RESULTS

The rate of mortality was 2 of 10 in the leukocyte-depletion group and 5 of 10 in control animals. The risk for early death in control animals was 2.5 (95% confidence interval, 0.63-10.0) times higher than that of the leukocyte-depleted animals. The median behavioral score at day 7 was higher in the leukocyte-depletion group (8.5 vs 3.5; P =.04). The median of total histopathologic score was 8.5 in the leukocyte-depletion group and 15.5 in the control group (P =.005).

CONCLUSION

A leukocyte-depleting filter improves brain protection after a prolonged period of hypothermic circulatory arrest.

Cytokine and S100B levels in paediatric patients undergoing corrective cardiac surgery with or without total circulatory arrest

OBJECTIVES

Neurological damage following cardiopulmonary bypass (CPB) is difficult to objectively evaluate in infants. In adults, serum elevations of astroglial S100B correlate with proven brain injury independent of operative temperature. The deleterious effects of inflammatory cytokines, generated during CPB, on the brain have not been studied in infants using S100B as a marker for cerebral injury.

METHODS

Twelve neonates, weighing 3.3 +/- 0.2 kg (total circulatory arrest group (TCA)) and 12 infants weighing 7.0 +/- 1.0 kg (cardiopulmonary bypass group (CPB)) underwent corrective cardiac surgery for various pathologies. Serial blood samples on induction, at the end of CPB, 30 min, 2 h and 24 h after the administration of protamine, were taken. The resultant plasma was frozen to -80 degrees C and stored for batch analysis. Cytokines were measured using ELISAs and S100B using a luminometric assay.

RESULTS

The TCA group were younger and experienced a longer perfusion time than the CPB group (137 +/- 8 vs. 113 +/- 7, P = 0.04). The mean TCA time was 23 +/- 4 min. The TCA group had significantly higher levels of IL-6 (P = 0.001), IL-8 (P = 0.005) and S100B (P = 0.002) at 24 h. C5b-9 levels were significantly lower in the TCA group: end of CPB (P = 0.001), 30 min (P < 0.001), 2 h (P = 0.002). There was a weak, but significant correlation between IL-6 levels at the end of CPB and S100B levels 2 h later (r = 0.55, P = 0.03). Long extubation times were associated with high 24-h S100B levels (r = 0.52, P = 0.01).

CONCLUSIONS

(1) The TCA group have prolonged rises of IL-6, IL-8 and S100B. (2) The TCA group generates significantly lower complement. (3) Astroglial injury, seen after surgery, may, in part, be cytokine mediated.