Is there a relationship between serum S-100beta protein and neuropsychologic dysfunction after cardiopulmonary bypass?

S100B in cardiac surgery brain monitoring: friend or foe?

Recent advances in perioperative management of adult and pediatric patients requiring open heart surgery (OHS) and cardiopulmonary bypass (CPB) for cardiac and/or congenital heart diseases repair allowed a significant reduction in the mortality rate. Conversely morbidity rate pattern has a flat trend. Perioperative period is crucial since OHS and CPB are widely accepted as a deliberate hypoxic-ischemic reperfusion damage representing the cost to pay at a time when standard of care monitoring procedures can be silent or unavailable. In this respect, the measurement of neuro-biomarkers (NB), able to detect at early stage perioperative brain damage could be especially useful. In the last decade, among a series of NB, S100B protein has been investigated. After the first promising results, supporting the usefulness of the protein as predictor of short/long term adverse neurological outcome, the protein has been progressively abandoned due to a series of limitations. In the present review we offer an up-dated overview of the main S100B pros and cons in the peri-operative monitoring of adult and pediatric patients.

Current Evidence Regarding Biomarkers Used to Aid Postoperative Delirium Diagnosis in the Field of Cardiac Surgery-Review

Postoperative cognitive disorders after cardiac surgery may manifest as postoperative delirium (POD) or later as postoperative cognitive dysfunction (POCD). The incidence of POD after cardiac surgery ranges from 16% to 73%. In contrast to POD, POCD is usually diagnosed after the discharge from hospital, with an incidence of 30 to 70% of cases, very often noticed only by close relative or friends, decreasing after six (20–30%) and twelve (15–25%) months after surgery. Perioperative cognitive disorders are associated with adverse short- and long-term effects, including increased morbidity and mortality. Due to the complexity of delirium pathomechanisms and the difficulties in the diagnosis, researchers have not yet found a clear answer to the question of which patient will be at a higher risk of developing delirium. The risk for POD and POCD in older patients with numerous comorbidities like hypertension, diabetes, and previous ischemic stroke is relatively high, and the predisposing cognitive profile for both conditions is important. The aim of this narrative review was to identify and describe biomarkers used in the diagnosis of delirium after cardiac surgery by presenting a search through studies regarding this subject, which have been published during the last ten years. The authors discussed brain-derived biomarkers, inflammation-related biomarkers, neurotransmitter-based biomarkers, and others. Work based on inflammation-related biomarkers, which are characterized by the low cost of implementation and the effectiveness of delirium diagnosis, seems to be the closest to the goal of discovering an inexpensive and effective marker. Currently, the use of a panel of tests, and not a single biomarker, brings us closer to the discovery of a test, or rather a set of tests ideal for the diagnosis of delirium after cardiac surgery.

Effects of dexamethasone on early cognitive decline after cardiac surgery: A randomised controlled trial

BACKGROUND

Postoperative cognitive decline (POCD), a very common complication after cardiac surgery, is characterised by impairment of both memory function and intellectual ability as well as being associated with increased use of healthcare resources. The investigators focused on the role of the inflammatory response to a surgical procedure as a potential factor involved in the pathogenesis of POCD.

OBJECTIVE

The use of prophylactic dexamethasone to attenuate the inflammatory response was hypothesised to reduce the risk of POCD.

DESIGN

Randomised controlled study.

SETTING

Single university teaching hospital, from March 2015 to January 2016.

PATIENTS

A total of 169 patients scheduled for elective cardiac surgery were enrolled, and 161 patients were included in the analyses.

INTERVENTION

Patients were randomised to receive a single intravenous bolus of 0.1 mg kg dexamethasone (n = 85) or placebo (n = 84) 10 h before the surgery.

MAIN OUTCOME MEASURES

The primary outcome measure in both groups was the incidence of POCD on the 6th day after surgery. The investigators also evaluated the effect of dexamethasone on the incidence of systemic inflammatory response syndrome, postoperative C-reactive protein levels and postoperative serum S100β protein levels.

RESULTS

Compared to the placebo group, the dexamethasone group showed statistically significant reductions in the incidence of POCD (relative risk, 0.43; 95% confidence interval, 0.21 to 0.89; P = 0.02), the incidence of systemic inflammatory response syndrome (30.0 versus 58.0%, P < 0.001) and postoperative C-reactive protein levels (P < 0.001). Postoperative S100β levels were insignificantly lower (P = 0.56) in the dexamethasone group.

CONCLUSION

Preoperative administration of dexamethasone reduced the inflammatory response and thereby decreased the risk of early POCD after cardiac surgery.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT02767713.

Effects of two differently heparin-coated extracorporeal circuits on markers for brain and myocardial dysfunction

Objective: The two most commonly used heparin-coated systems for cardiopulmonary bypass (CPB) are the Carmeda Bio-Active Surface (CBAS) (Medtronic, Minneapolis, MN, USA) and the Duraflo II coating (Baxter Healthcare, Irvine, CA, USA). The two surfaces are technically unequal and previous experimental studies have demonstrated disparities in effects on the immune system and blood cells. However, little is known concerning the influence of the two surfaces on markers for brain and myocardial dysfunction.

Methods: Forty patients undergoing elective, primary coronary bypass grafting with CPB were prospectively randomized to either the CBAS system or the Duraflo II circuit. During and after CPB, biological markers for brain dysfunction and myocardial injury were analysed.

Results: Both markers for brain dysfunction S-100B and neuron-specific enolase (NSE) increased significantly during CPB ( p =0.01). The elevation during bypass correlated significantly with the duration of CPB ( r = 0.39 and r= 0.38, respectively, both p< 0.02). NSE was somewhat more elevated in the Duraflo II group at the end of CPB ( p =0.01) and 5 h after CPB ( p= 0.02); for S-100B, there were no intergroup differences. Also, the markers related to myocardial injury, myoglobin and creatine kinase (CK-MB) mass increased during CPB ( p= 0.01), while elevation of troponin-I occurred 5 h after CPB ( p= 0.01). There were no statistically significant intergroup differences. No significant correlation was seen between the release of cardiac markers and the duration of CPB. The clinical course was similar in both groups.

Conclusions: Except for a slightly higher elevation of NSE at the end of CPB and 5 h after CPB in the Duraflo II group, there were no significant differences between the CBAS group and the Duraflo II group concerning markers for brain and myocardial dysfunction.

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.

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.

Antibodies against N-methyl-D-aspartate receptors in patients with systemic lupus erythematosus without major neuropsychiatric syndromes

PURPOSE

Approximately 14-54% of patients with systemic lupus erythematosus without a history of major neuropsychiatric syndromes (nonNPSLE) have cognitive deficits. Elevated N-methyl-D-aspartate (NMDA) receptor antibodies (anti-NR2) have been reported in 35% of patients with SLE, but few studies have utilized controls or a composite memory index. We hypothesized that serum anti-NR2 would be elevated in nonNPSLE compared to healthy controls, and that elevated anti-NR2 would be associated with memory dysfunction and depression.

METHODS

Subjects included 43 nonNPSLE patients with a mean age of 36.5 (SD=9.0) and mean education level of 14.7 years (SD=2.5). Twenty-seven healthy control subjects with similar demographic characteristics were also enrolled in this study. A global Cognitive Impairment Index (CII) and a Memory Impairment Index (MII) were calculated using impaired test scores from the ACR-SLE neuropsychological battery. Serum samples were analyzed using a standard ELISA for anti-NR2.

RESULTS

Elevations of serum anti-NR2 were found in 14.0% of the nonNPSLE and 7.4% of the controls (p=0.47). There was no relationship between elevated anti-NR2 status and higher CII or performance on the MII. No relationship between levels of depressive symptoms and anti-NR2 was found.

CONCLUSIONS

The frequency of elevated anti-NR2 was low (14.0%) in this sample of SLE patients and not significantly different from controls. A relationship was not found between the presence of anti-NR2 in serum and global cognitive or memory indices, or with depression. Results suggest that serum anti-NR2 is not likely related to mild cognitive dysfunction in SLE patients without a prior history of NPSLE.

Evaluation of methods to predict early long-term neurobehavioral outcome after coronary artery bypass grafting

Postoperative cognitive decrease (POCD) represents the most frequent complication in modern cardiac surgery. The application of easily assessable surrogate parameters that predict long-term POCD at early time points is tempting. The aim of the present study was to analyze the predictive value of cerebral biomarkers, diffusion-weighted magnetic resonance imaging (DWI), and cognitive bedside testing after coronary artery bypass grafting (CABG). From 106 patients who underwent elective CABG, blood samples were drawn for the measurement of protein S100B and neuron-specific enolase release at baseline, at the end of surgery, and 48 hours afterward. Cerebral DWI was carried out before and 2 to 4 days after surgery. Cognitive functioning was assessed before, 2 to 4 days (bedside testing) after, and 3 months after CABG. On DWI, lesions were detected in 15.1% of patients. Biomarker levels and the presence of acute ischemic lesions on DWI were not associated with long-term POCD. Early POCD was correlated with 3-month POCD (r = 0.46, p <0.001). Ninety-one percent of patients who had shown moderate to severe POCD (<-1.5 z scores) in the early phase still had decreased memory functioning at 3 months compared to baseline (likelihood ratio 5.23). Early POCD was asserted as the only predictor for long-term POCD in a stepwise multiple linear regression model (R(2) = 0.20, p <0.001), excluding age, length of surgery, aortic clamping and cardiopulmonary bypass duration, the number of anastomoses, and postoperative neuron-specific enolase and S100B levels. In conclusion, the results show that in contrast to biomarkers, DWI, age, or intraoperative variables, early neuropsychological bedside testing predicts long-term POCD after CABG with acceptable accuracy.

Antibodies to S100 proteins have anxiolytic-like activity at ultra-low doses in the adult rat

S100 proteins are small calcium-binding proteins interacting with numerous intra- and extra cellular targets involved in diverse physiological functions. In particular, S100 proteins may be involved in the regulation of anxiety-related behaviour. In the present study, the effects of affinity-purified antibodies to S100 proteins administered orally at ultra-low doses were evaluated in pre-clinical tests for anxiolytic-like activity in the adult rat. In the Vogel conflict test in the rat, antibodies to S100 proteins increased punished drinking (anti-conflict effect) at 5 and 7.5 mL kg−1, but not at 2.5 or 10 mL kg−1. Antibodies to S100 proteins increased the percentage of entries into the open arms of an elevated plus-maze at 10 mL kg−1, but not at lower doses. Taken together, these results indicate the presence of anxiolytic-like activity for antibodies to S100 proteins over the dose range 5–10 mL kg−1 in the adult rat.

Evaluation of an alternative S100b assay for use in cardiac surgery: relationship with microemboli and neuropsychological outcome

INTRODUCTION

The aim of the study was to investigate the relationship between S100b release, neuropsychological outcome and cerebral microemboli. Peri-operative assay of the astroglial cell protein S100b has been used as a marker of cerebral damage after cardiac surgery but potential assay cross-reactivity has limited its specificity. The present study uses an alternative enzyme-linked immunoabsorbant assay (ELISA) for serum S100b that has documented sensitivity and specificity data in patients undergoing coronary artery bypass grafting (CABG).

METHODS

Fifty-five consecutive patients undergoing routine CABG surgery received serial venous S100b sampling at five time points: i) Pre-operative, ii) At the end of cardiopulmonary bypass (CPB), iii) 6 hrs, iv) 24 hrs and v) 48 hrs post skin closure. A previously described sandwich ELISA with monoclonal anti- S100b was used. This assay has a lower limit of detection of 0.04 microg/L and < 0.006% reactivity with S100a at a concentration of 100 microg/L S100a. Cerebral microemboli during surgery were recorded by transcranial Doppler monitor over the right middle cerebral artery. Evidence of cerebral impairment was obtained by comparing patients' performance in a neuropsychological battery of 9 tests administered 6-8 weeks post-operatively with their pre-operative scores.

RESULTS

There was a significant increase in S100b only at the end of bypass (mean 0.30 microg/L, SD +/- 0.33 and range .00 to 1.57). S100b levels at the end of bypass did not correlate with neuropsychological outcome or microemboli counts.

CONCLUSIONS

The low levels of S100b detected using the present assay, despite its high sensitivity and despite the routine use of cardiotomy suction, suggest that the assay may have higher specificity for cerebral S100b than previously used assays. There was no evidence that this assay is related to neuropsychological change or cerebral microemboli in cardiac surgery.

The effects of isoflurane, sevoflurane, and desflurane anesthesia on neurocognitive outcome after cardiac surgery: a pilot study

BACKGROUND

Inhalation anesthetics such as isoflurane, sevoflurane, and desflurane are widely used in clinical practice; however, there is no study for comparing these drugs in cardiac surgery with respect to postoperative cognitive outcome and S100 beta protein (S100 BP) levels. In this study, we evaluated the effect of sevoflurane, isoflurane, and desflurane anesthesia on neuropsychological outcome and S100 BP levels in patients undergoing coronary artery bypass grafting (CABG) surgery with cardiopulmonary bypass (CPB).

MATERIALS AND METHODS

Forty-two male patients were prospectively randomized and classified into 3 groups according to the volatile agents used; isoflurane, sevoflurane, desflurane. All patients had a sufficient education level to participate in neuropsychological testing and a normal carotid Doppler ultrasonography. Blood samples for analysis of S100 BP were collected before anesthesia (T1), before heparinization (T2), 15 minutes into CPB (T3), following protamine administration (T4), postoperatively (T5), 24 hours after the operation (T6), postoperative day 3 (T7), and postoperative day 6 (T8). The neuropsychological tests, including Mini-Mental State Examination (MMSET) and visual-aural digit span test (VADST), were administered 1 day prior to surgery and on the third and sixth postoperative days.

RESULTS

The postoperative third and sixth day MMSET scores and third day visual-written subtest scores in the sevoflurane group were significantly lower than in the isoflurane and desflurane groups (P < .05). S100 BP levels increased with the beginning of anesthesia in the sevoflurane and desflurane groups. Although S100 BP decreased to baseline levels on postoperative day 1 in the sevoflurane group, this was significantly higher on the third and sixth days postoperatively in the desflurane group (P < .05). In the isoflurane group, the S100 BP level was significantly higher than the baseline level only after CPB (P < .05).

CONCLUSION

Our study suggests that isoflurane is associated with better neurocognitive functions than desflurane or sevoflurane after on-pump CABG. Sevoflurane seems to be associated with the worst cognitive outcome as assessed by neuropsychologic tests, and prolonged brain injury as detected by high S100 BP levels was seen with desflurane.

Serologic markers of brain injury and cognitive function after cardiopulmonary bypass

OBJECTIVE

To examine the association between biochemical markers of brain injury (MBI) and the inflammatory response in relation to neurocognitive deficiency (NCD) after cardiopulmonary bypass (CPB).

SUMMARY BACKGROUND DATA

In cardiac surgery, NCD is a common but underdiagnosed complication with an unclear pathophysiology leading to significant morbidity. Despite extensive investigation, identification of a MBI for clinical use and clarifying the pathophysiology of NCD have not been achieved.

METHODS

Forty patients undergoing CABG and/or valve procedures using CPB were administered a validated neurocognitive battery preoperatively and postoperatively at day 4 and 3 months. S-100b, neuron specific enolase (NSE), and tau protein were assayed as MBIs preoperatively and postoperatively at 6 hours and day 4. C-reactive protein (CRP), interleukin (IL)-6, C3a, and total peroxide levels were also quantified from serum. Impact of cardiotomy suction and antifibrinolytics on markers of brain injury was assessed.

RESULTS

The incidence of early NCD was 40% (16 of 40). NSE and tau protein at the 6-hour time point were both significantly elevated in the presence of NCD (NCD group) compared with those without NCD (NORM group) (8.69 +/- 0.82 vs. 5.98 +/- 0.61; P = 0.018 and 68.8 vs. 29.2%; P = 0.015; respectively). S-100b increase was not different between the NCD and NORM groups. Cardiotomy suction significantly elevated S-100b levels, whereas NSE and tau were not significantly influenced. Aprotinin did not have an effect on NCD or levels of MBIs. Also, the NCD group had significantly elevated CRP and peroxide levels compared with the NORM group at postoperative day 4 while C3a was significantly elevated at 6 hours.

CONCLUSION

NSE and tau are better associated with NCD and less influenced by cardiotomy suction compared with S-100beta. Inflammatory and oxidative stress is associated with NCD post-CPB.

Randomized Controlled Trial of Pericardial Blood Processing With a Cell-Saving Device on Neurologic Markers in Elderly Patients Undergoing Coronary Artery Bypass Graft Surgery

BACKGROUND

Processing of pericardial shed blood with a cell-saving device was claimed to prevent lipid microembolization and to protect from neurocognitive dysfunction after cardiopulmonary bypass. The present study tested the hypothesis that processing of pericardial shed blood with a cell-saving device during cardiopulmonary bypass would significantly decrease serum levels of protein S100B, and improve brain oxygen saturation and neurologic outcome, all markers of brain injury in elderly patients.

METHODS

Forty patients, 65 years of age and older, undergoing coronary artery bypass graft with cardiopulmonary bypass, were prospectively randomly assigned to processing of pericardial shed blood with a cell-saving device or to conventional use of a standard closed venous reservoir where cardiotomy blood was collected and reinfused through the arterial circuit (control group). Serum in S100B was measured 30 minutes, 4 hours, 24 hours, and 48 hours after surgery. Near-infrared spectroscopy monitoring was performed during the procedure and the National Institutes of Health stroke scale was measured before surgery and at the time of discharge of the hospital.

RESULTS

Patients in the cell-saving device group averaged 72 +/- 3 years of age and underwent 3.1 +/- 0.7 coronary artery grafts with a mean of 62 +/- 20 minutes of cardiopulmonary bypass time. Patients in the control group averaged 75 +/- 4 years of age (p = 0.03) and underwent 3.3 +/- 0.6 coronary artery grafts (p = 0.49) with a mean of 75 +/- 25 minutes of cardiopulmonary bypass time (p = 0.12). The quantity of blood administered from the cell-saving device averaged 281 +/- 162 mL per patient. Serum protein S100B levels averaged 0.06 +/- 0.03 before surgery and 0.51 +/- 0.23 microg/L 30 minutes after surgery in the cell-saving device patients compared with 0.076 +/- 0.04 before surgery (p = 0.32) and 1.48 +/- 0.66 (p < 0.0001) in the control patients. The near-infrared spectroscopy baseline mean value of left and right cortical region was 58% +/- 12% and 55% +/- 7% in the cell-saving device group versus 59% +/- 7% and 53% +/- 6% in the control group (p = 0.67 and 0.36), and no difference occurred over time in each group. The National Institutes of Health stroke score before and after surgery was similar in the two groups. There was one cerebrovascular complication in the control group (1 of 20, 5%) after surgery.

CONCLUSIONS

The difference between the two groups occurred 30 minutes after surgery, at which time serum levels of protein S100B were significantly higher in the control group compared with cell-saving device patients. Although use of the cell-saving device was not associated with higher brain oxygen saturation nor changes in the National Institutes of Health stroke score, it is associated with lesser release of nonspecific markers of brain injury in elderly patients.

Neurologic complications of cardiac surgery: Current concepts and recent advances

Neurologic complications following cardiac surgery result in increased morbidity and mortality. The incidence of stroke is 2% to 4%, but is substantially higher in patients with a prior history of stroke. The success of off-pump techniques in altering this risk is controversial. The efficacy and safety of simultaneous carotid endarterectomy and coronary artery bypass surgery are still debated. Mechanical clot retrievers may offer new opportunity to treat postoperative large, middle cerebral artery strokes. The risk of cognitive deficits is debatable but may be due to factors other than the use of bypass and may not differ from similar deficits after noncardiac surgery. Short-term cognitive deficits usually resolve by 1 to 3 months. Long-term risks are not clearly established. Novel approaches may decrease the incidence of neurocognitive dysfunction. Postoperative seizures may result from global or focal cerebral ischemia due to hypoperfusion, particulate or air emboli, or metabolic causes. Newer anticonvulsant drugs may offer additional management opportunities.

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.

Induction and detection of disturbed homeostasis in cardiopulmonary bypass

During cardiopulmonary bypass (CPB) haemodynamic alterations, haemostasis and the inflammatory response are the main causes of homeostatic disruption. Even with CPB procedures of short duration, the homeostasis of a patient is disrupted and, in many cases, requires intensive postoperative treatment to re-establish the physiological state of the patient. Although mortality is low, disruption of homeostasis may contribute to increased morbidity, particularly in high-risk patients. Over the past decades, considerable technical improvements in CPB equipment have been made to prevent the development of the systemic inflammatory response syndrome (SIRS). Despite all these improvements, only the inflammatory response, to some extent, has been reduced. The microcirculation is still impaired, as measured by tissue degradation products of various organs, indicating that CPB may still be considered as an unphysiological procedure. The question is, therefore, whether we can detect the pathophysiological consequences of CPB in each individual patient with valid bedside markers, and whether we can relate this to determinant factors in the CPB procedure in order to assist the perfusionist in improving the adequacy of CPB. The use of these markers could play a pivotal role in decision making by providing an immediate feedback on the determinant quality of perfusion. Therefore, we suggest validating the proposed markers in a nomogram to optimize not only the CPB procedure, but also the patient's safety.

Controversial significance of early S100B levels after cardiac surgery

Background

The brain-derived protein S100B has been shown to be a useful marker of brain injury of different etiologies. Cognitive dysfunction after cardiac surgery using cardiopulmonary bypass has been reported to occur in up to 70% of patients. In this study we tried to evaluate S100B as a marker for cognitive dysfunction after coronary bypass surgery with cardiopulmonary bypass in a model where the inflow of S100B from shed mediastinal blood was corrected for.

Methods

56 patients scheduled for coronary artery bypass grafting underwent prospective neuropsychological testing. The test scores were standardized and an impairment index was constructed. S100B was sampled at the end of surgery, hourly for the first 6 hours, and then 8, 10, 15, 24 and 48 hours after surgery. None of the patients received autotransfusion.

Results

In simple linear analysis, no significant relation was found between S100B levels and neuropsychological outcome. In a backwards stepwise regression analysis the three variables, S100B levels at the end of cardiopulmonary bypass, S100B levels 1 hour later and the age of the patients were found to explain part of the neuropsychological deterioration (r = 0.49, p < 0.005).

Conclusions

In this study we found that S100B levels 1 hour after surgery seem to be the most informative. Our attempt to control the increased levels of S100B caused by contamination from the surgical field did not yield different results. We conclude that the clinical value of S100B as a predictive measurement of postoperative cognitive dysfunction after cardiac surgery is limited.

[Neuromonitoring with S-100 protein in the intensive care unit]

During the last years biochemical neuromonitoring with various molecules such as S-100 protein has become popular. A huge number of investigations both experimental and clinical have been undertaken to determine diagnosis and prognosis of patients with acute neurologic diseases. This article gives a review on the current knowledge, indications and limitations on the use of S-100 protein with regard to most of the acute neurological diseases an intensivist is confronted with in everyday practice.

Interaction of temperature with hematocrit level and pH determines safe duration of hypothermic circulatory arrest

OBJECTIVE

Previous studies have demonstrated that both hematocrit level and pH influence the protection afforded by deep hypothermic circulatory arrest. The current study examines how temperature modulates the effect of hematocrit level and pH in determining a safe duration of circulatory arrest. The study also builds on previous work investigating the utility of near-infrared spectroscopy as a real-time monitor of cerebral protection during circulatory arrest.

METHODS

Seventy-six piglets (9.3 +/- 1.2 kg) underwent circulatory arrest under varying conditions with continuous monitoring by means of near-infrared spectroscopy (hematocrit level of 20% or 30%; pH-stat or alpha-stat strategy; temperature of 15 degrees C or 25 degrees C; arrest time of 60, 80, or 100 minutes). Neurologic recovery was evaluated daily by a veterinarian, and the brain was fixed in situ on postoperative day 4 to be examined on the basis of histologic score in a blinded fashion.

RESULTS

Multivariable analysis of total histologic score revealed that higher temperature, lower hematocrit level, more alkaline pH, and longer hypothermic circulatory arrest duration were predictive of more severe damage to the brain (P <.01). Regression modeling revealed that higher temperature exacerbated the disadvantage of a lower hematocrit level and longer arrest times but not pH strategy. Normalized oxyhemoglobin nadir time, derived from near-infrared spectroscopy, was positively correlated with neurologic recovery on the fourth postoperative day and with total histologic injury score (P <.0001).

CONCLUSION

Hematocrit level and pH, as well as temperature, determine the safe duration of hypothermic circulatory arrest. Near-infrared spectroscopy is a useful real-time monitor of safe duration of circulatory arrest.

Propofol offers no advantage over isoflurane anesthesia for cerebral protection during cardiopulmonary bypass: a preliminary study of S-100ß protein levels

PURPOSE

Despite advances in anesthesia, cardiopulmonary bypass (CPB) and surgical techniques, cerebral injury remains a major source of morbidity after cardiac surgery. We compared the effects of two different anesthetic techniques, isoflurane vs propofol on neurological outcome by serum S-100beta protein and neuropsychological tests after coronary artery bypass grafting (CABG).

METHODS

Twenty patients undergoing CABG, randomly allocated into two groups, were enrolled in this prospective, controlled, preliminary study. Isoflurane was used in group I and propofol in group P. Neurological examination and a neuropsychologic test battery consisting of the mini mental state examination (MMSET) and the visual aural digit span test (VADST) were obtained preoperatively and on the third and sixth postoperative days. Blood samples for analysis of S-100beta protein were collected before anesthesia (T1), after heparinization (T2), 15 min into CPB (T3), after CPB (T4) and at the 24(th) hr postoperatively (T5).

RESULTS

Postoperative neurological examinations of the patients were normal. VADST performance declined significantly on the third day (P < 0.05) in both groups, and there were no significant differences on VADST and MMSET scores between the two groups. In group P, S-100beta protein levels increased significantly at T3 and T4 compared to preoperative and isoflurane levels (P < 0.05).

CONCLUSIONS

Despite reports about the neuroprotective effects of propofol, S-100beta protein levels were significantly elevated in group P. Although there was no deterioration in neuropsychological outcome, propofol appeared to offer no advantage over isoflurane for cerebral protection during CPB in this preliminary study of 20 patients.

Neurocognitive outcome after retrograde cerebral perfusion

BACKGROUND

Neurocognitive outcome in patients undergoing thoracic aortic surgery using retrograde cerebral perfusion (RCP) remains uncertain.

METHODS

Forty-two patients undergoing thoracic aortic surgery using RCP were enrolled in the study. The patients' neurocognitive state was assessed by the revised Wechsler Adult Intelligence Scale (WAIS-R) a few days before operation, at 2 to 3 weeks, and at 4 to 6 months after operation.

RESULTS

There were no stroke, seizure, and hospital death. Significant performance deterioration was observed in digit span, arithmetic, and picture completion of the WAIS-R subtests. Bivariate comparison showed that older age (late vocabulary, late similarities, and late object assembly), longer RCP time (early picture arrangement, and early block design), later awake time (early and late picture arrangement, and early block design), longer respirator use (early and late digit span, late picture arrangement), longer ICU time (late picture completion, early and late picture arrangement, and early block design), and longer hospital stay (early picture arrangement) were significantly associated with the decline in neurocognitive performance. Stepwise logistic regression analysis disclosed that older age (late similarities and late object assembly), later awake time (late picture arrangement), and longer respirator use (early and late digit span, and late picture arrangement) were most predictive for the decline in neurocognitive performance.

CONCLUSIONS

On average, digit span, arithmetic, and picture completion tests were most sensitive in detecting the decline in neurocognitive performance. The relationship between the duration of RCP and neurocognitive test results was not significant.

Predictive value of brain-specific proteins in serum for neurodevelopmental outcome after birth asphyxia

Brain-specific proteins have been used to detect cerebral injury after birth asphyxia. Previous investigations suggest that serum protein S-100beta, brain-specific creatine kinase (CK-BB), and neuron-specific enolase (NSE) are capable of identifying patients with a risk of developing hypoxic-ischemic encephalopathy. Whether detection of elevated serum concentrations of these proteins reflects long-term neurodevelopmental impairment remains to be investigated. We examined serum protein S-100beta, NSE, and CK-BB at 2, 6, 12, and 24 h after birth in 29 asphyxiated infants and 20 control infants. Neurodevelopmental follow-up examinations were performed at 20 mo of age using the German revision of the Griffiths scales for developmental assessment. Elevated concentrations of serum protein S-100beta, NSE, and CK-BB within 24 h after asphyxia did not correlate with long-term neurodevelopmental delay. We conclude that serum protein S-100beta, NSE, and CK-BB, sampled on the first day of life, is of limited value in predicting severe brain damage after birth asphyxia.

Serial measurement of serum S-100B protein as a marker of cerebral damage after cardiac surgery

BACKGROUND

We used serial measurements of serum S-100B protein to evaluate the time course of serum S-100B protein concentration after cardiovascular surgery and to determine the clinical relevance of its concentration and cerebral damage.

METHODS

We assessed neurologic function in 149 patients undergoing cardiovascular surgery with cardiopulmonary bypass. The patients were classified into three groups according to their early postoperative outcome: those without complications (group A), those having unconsciousness or convulsion or both but no hemiplegia (group B), and those having unconsciousness and hemiplegia either with or without convulsion (group C). Serum S-100B protein concentrations were measured with a commercially available immunoluminometric assay, Sangtec 100 LIA, at seven time-points: before cardiopulmonary bypass, at the end of cardiopulmonary bypass, and at 5, 12, 24, 48, and 72 hours after cardiopulmonary bypass.

RESULTS

At 5 hours after cardiopulmonary bypass, the S-100B values in groups B and C were significantly higher than the value in group A. Although the S-100B level decreased in group C during the first 5 hours after cardiopulmonary bypass, it increased thereafter (12 through 24 hours) and continued at a high level until the final measurement at 72 hours. At 12 hours after cardiopulmonary bypass, S-100B was significantly higher in group C than in group B. This late increase in S-100B was associated with radiologically detected abnormalities and cerebral damage.

CONCLUSIONS

Serial measurement of serum S-100B protein in the initial 12 hours after cardiopulmonary bypass can be used to predict early postoperative brain injury.

The effect of zero-balanced ultrafiltration during cardiopulmonary bypass on S100b release and cognitive function

Zero-balanced ultrafiltration (ZBUF) might reduce the systemic inflammatory response (SIRS) during cardiopulmonary bypass (CPB) by removing inflammatory mediators. The objective of this study was to determine the effect of ZBUF on postoperative serum S100b levels, a marker of neuronal injury. In addition, the possible effects of ZBUF on postoperative neurocognitive function were assessed. Sixty patients undergoing elective coronary bypass grafting were randomly assigned either to a control group or to a protocol group in which ZBUF was performed. Serum S100b levels were measured five minutes after intubation, at the end of bypass and eight and 20 hours after arrival at the intensive care unit (ICU). Cognitive function was assessed with neuropsychological tests on the day before the operation and the sixth day after surgery. The S100b level at 20 hours after arrival at the ICU was 0.27 g/L (SD 0.16) in the control and 0.25 g/L (SD 0.12) in the group with ZBUF. There were no statistical differences at any time between the two groups. S100b was not detectable in the ultrafiltrate, indicating that these results were not obscured by washout of S100b. Thirteen patients (52%) in the control group and 14 patients (56%) in the ZBUF group showed a cognitive deficit. In conclusion, ZBUF during CPB does not decrease the release of S100b. This result is not affected by washout. ZBUF did not reduce the incidence of early neurocognitive deficits. The role of SIRS in the development of cognitive dysfunction following CPB remains to be resolved.

Assessment of neurocognitive impairment after off-pump and on-pump techniques for coronary artery bypass graft surgery: prospective randomised controlled trial

OBJECTIVE

To assess neurocognitive impairment after the off-pump and on-pump techniques for coronary artery bypass graft surgery in patients with triple vessel disease.

DESIGN

Randomised controlled trial.

SETTING

University Hospital of Wales, Cardiff.

PARTICIPANTS

60 patients undergoing coronary artery bypass graft surgery for triple vessel disease prospectively randomised to the off-pump or on-pump technique.

MAIN OUTCOME MEASURES

Change in scores in nine standard neuropsychometric tests administered preoperatively and at 1 and 10 weeks postoperatively.

RESULTS

The on-pump group showed a significantly greater deterioration in scores for two and three tests at 1 week and 10 weeks postoperatively, respectively, than the off-pump group. The on-pump group also showed a significantly higher incidence of major deterioration in one of the tests both 1 week and 10 weeks postoperatively. The incidence of neurocognitive impairment at 1 week postoperatively was 27% (8 out of 30) in the off-pump group and 63% (19 out of 30) in the on-pump group (P=0.004); and at 10 weeks postoperatively was 10% (3 out of 30) in the off-pump group and 40% (12 out of 30) in the on-pump group (P=0.017).

CONCLUSION

Off-pump coronary artery bypass graft surgery results in less neurocognitive impairment than the on-pump technique.

Early elevation of S-100B protein in blood after cardiac surgery is not a predictor of ischemic cerebral injury

BACKGROUND

We hypothesized that early changes in S-100B levels after cardiac surgery are nonspecific and mostly reflect damage to tissues outside the brain rather than ischemic brain damage.

METHODS

We measured serum levels of S-100B at several times perioperatively in 21 patients undergoing cardiac surgery. In addition, we measured levels of neuron specific enolase (NSE), glial fibrillary acidic protein (GFAP), creatine kinase (CK), the cardiac isoenzyme of CK (CK-MB), and myoglobin (MB) in these patients.

RESULTS

Early increases in serum S-100B concentration were significantly (p<0.01) correlated with increases in markers of tissue injury outside the brain: S-100B/CK: r(2)=0.69; S-100B/CK-MB: r(2)=0.64; S-100B/myoglobin: r(2)=0.60; S-100B/NSE: r(2)=0.51; CK/NSE: r(2)=0.60; CK-MB/NSE: r(2)=0.59; and myoglobin/NSE: r(2)=0.54.

CONCLUSIONS

Our findings indicate that increases in S-100B in the early phase after cardiac surgery are not due to release of S-100B from brain alone but also from tissue outside the brain.

Neurological Complications of Aortic Surgery

Surgery of the aortic arch involves an inherently high risk of neurological complications. A number of factors have been identified which may predispose the patient to brain injury, and various techniques employed in an attempt to counteract these are outlined. In particular the vulnerability of the brain to ischemia has led to the development of three adjunctive cerebral protective techniques, hypothermic circulatory arrest, retrograde cerebral perfusion and selective antegrade cerebral perfusion, all based upon brain cooling and metabolic inhibition. The relative merits and disadvantages of these techniques are therefore discussed. Finally, pharmacologic adjuncts and potential future developments in aortic arch surgery are discussed.

Is there an association between release of protein S100B during cardiopulmonary bypass and memory disturbances?

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.

Molecular Mechanisms of Neurologic Injury Following Cardiopulmonary Bypass

Neurologic injury is a potentially devastating consequence of heart surgery. Between 1% and 5% of patients undergoing cardiopulmonary bypass have postoperative strokes and 30% to 80% of patients demonstrate some neurologic dysfunction postoperatively. This review focuses on anatomic, molecular and clinical markers of neurologic injury following cardiopulmonary bypass. Attention is directed to the molecular mechanisms underlying neurologic injury and clinical biochemical markers of injury during heart surgery. Novel strategies to modulate injury are also discussed.

Postoperative course of S-100B protein and neuron-specific enolase in patients after implantation of continuous and pulsatile flow LVADs

BACKGROUND

In the early post-operative period after implantation of a continuous flow left ventricular assist device (LVAD) a non-pulsatile flow occurs. We compared the post-operative time-courses of protein S-100B (S100B) and neuron-specific enolase (NSE) as biochemical markers of brain injury in patients after implantation of a continuous flow LVAD and patients receiving a pulsatile flow LVAD.

METHODS

Since 1998 the continuous flow DeBakey VAD has been implanted in 8 patients at our institution. For comparison purposes, a group of 7 consecutive patients in whom a pulsatile Novacor N100 LVAD was implanted were investigated. In both groups cardiopulmonary bypass (CPB) with cardiotomy suction was used. S100B and NSE were measured in serum pre-operatively, 4 hours after CPB, and on days 1, 3, 7, and 14 after implantation of the LVAD. A neurologic examination was performed pre-operatively and post-operatively on days 3 and 14.

RESULTS

No differences were found between groups in pre-operative characteristics. The analysis of variance with repeated measurements for S-100B and NSE showed significant time effects (p = 0.004, p = 0.009, respectively) but no group effects (p = 0.06, p = 0.26, respectively) and no interaction between groups and time (p = 0.12, p = 0.48, respectively). The pre-operative serum level of S100B was significantly higher (p = 0.03) in the DeBakey VAD group. The pre-operative serum level of NSE was similar in the 2 groups (p = 0.7). In both groups there was a significant increase of S100B and NSE immediately after surgery (S100B: p = 0.006, p = 0.019; NSE: p = 0.01, p = 0.001). The values returned to pre-operative levels in the DeBakey VAD group on day 1 after implantation and in the Novacor group for S100B on day 3 and NSE on day 1. Post-operatively the mean values of S100B and NSE in the DeBakey VAD group compared with the Novacor group were significantly elevated only on day 3 (p = 0.005, p = 0.023).No neurologic complications were noted in patients with a continuous flow LVAD, whereas in the pulsatile LVAD group 2 patients presented neurologic abnormalities during the study period.

CONCLUSIONS

The similar course of biochemical markers of brain damage in both groups may indicate that the non-pulsatile flow in the early post-operative period does not lead to increased brain injury or permeability of the brain blood barrier.Elevated levels of S100B and NSE in the post-operative period can be used as diagnostic markers of brain injury in patients after implantation of both types of LVAD.

Retrograde cerebral perfusion as a method of neuroprotection during thoracic aortic surgery

Retrograde cerebral perfusion is commonly used as an adjunct to hypothermic circulatory arrest to enhance cerebral protection during thoracic aortic surgery. This review summarizes a large number of studies that demonstrate a spectrum of beneficial, neutral, and detrimental effects of retrograde cerebral perfusion in humans and experimental animal models. It remains unclear whether retrograde cerebral perfusion provides effective cerebral perfusion, metabolic support, washout of embolic material, and improved neurological and neuropsychological outcome.

Prediction of safe duration of hypothermic circulatory arrest by near-infrared spectroscopy

OBJECTIVE

Hypothermic circulatory arrest is widely used for adults with aortic arch disease as well as for children with congenital heart disease. At present, no method exists for monitoring safe duration of circulatory arrest. Near-infrared spectroscopy is a new technique for noninvasive monitoring of cerebral oxygenation and energy state. In the current study, the relationship between near-infrared spectroscopy data and neurologic outcome was evaluated in a survival piglet model with hypothermic circulatory arrest.

METHODS

Thirty-six piglets (9.36 +/- 0.16 kg) underwent circulatory arrest under varying conditions with continuous monitoring by near-infrared spectroscopy (temperature 15 degrees C or 25 degrees C, hematocrit value 20% or 30%, circulatory arrest time 60, 80, or 100 minutes). Each setting included 3 animals. Neurologic recovery was evaluated daily by neurologic deficit score and overall performance category. Brain was fixed in situ on postoperative day 4 and examined by histologic score.

RESULTS

Oxygenated hemoglobin signal declined to a plateau (nadir) during circulatory arrest. Time to nadir was significantly shorter with lower hematocrit value (P <.001) and higher temperature (P <.01). Duration from reaching nadir until reperfusion ("oxygenated hemoglobin signal nadir time") was significantly related to histologic score (r (s) = 0.826), neurologic deficit score (r (s) = 0.717 on postoperative day 1; 0.716 on postoperative day 4), and overall performance category (r (s) = 0.642 on postoperative day 1; 0.702 on postoperative day 4) (P <.001). All animals in which oxygenated hemoglobin signal nadir time was less than 25 minutes were free of behavioral or histologic evidence of brain injury.

CONCLUSION

Oxygenated hemoglobin signal nadir time determined by near-infrared spectroscopy monitoring is a useful predictor of safe duration of circulatory arrest. Safe duration of hypothermic circulatory arrest is strongly influenced by perfusate hematocrit value and temperature during circulatory arrest.

The systemic inflammatory response after cardiac surgery with cardiopulmonary bypass in children

Paediatric cardiac surgery often requires cardiopulmonary bypass (CPB) during the surgical intervention. CPB is known to elicit a systemic inflammatory response with activation of the complement and coagulation systems, stimulation of cytokine production, cellular entrapment in organs, neutrophil activation with degranulation, platelet activation, and endothelial dysfunction. These changes are associated with a risk of postoperative organ dysfunction and increased morbidity and mortality in the postoperative period. Clinical studies have concentrated on measurement of inflammatory markers and mediators in peripheral blood, where the systemic inflammatory response in the paediatric cardiac patient seems to be different from the adult case. Looking at the organ level, experimental studies have the advantage of providing information contributing to a better understanding of the pathological events that may lead to the deteriorated organ function. This review focuses on the systemic inflammatory response after cardiac surgery with CPB in children and experimental CPB models.

Early biochemical indicators of hypoxic-ischemic encephalopathy after birth asphyxia

Hypoxic-ischemic encephalopathy (HIE) after perinatal asphyxia is a condition in which serum concentrations of brain-specific biochemical markers may be elevated. Neuroprotective interventions in asphyxiated newborns require early indicators of brain damage to initiate therapy. We examined brain-specific creatine kinase (CK-BB), protein S-100, and neuron-specific enolase in cord blood and 2, 6, 12, and 24 h after birth in 29 asphyxiated and 20 control infants. At 2 h after birth, median (quartiles) serum CK-BB concentration was 10.0 U/L (6.0-13.0 U/L) in control infants, 16.0 U/L (13.0-23.5 U/L) in infants with no or mild HIE, and 46.5 U/L (21.4-83.0 U/L) in infants with moderate or severe HIE. Serum protein S-100 was 1.6 microg/L (1.4-2.5 microg/L) in control infants, 2.9 microg/L (1.8-4.7 microg/L) in asphyxiated infants with no or mild HIE, and 17.0 microg/L (3.2-34.1 microg/L) in infants with moderate or severe HIE 2 h after birth. No significant difference was detectable in serum neuron-specific enolase between infants with no or mild and moderate or severe HIE 2 and 6 h after birth. A combination of serum protein S-100 (cutoff value, 8.5 microg/L) and CK-BB (cutoff value, 18.8 U/L) 2 h after birth had the highest predictive value (83%) and specificity (95%) of predicting moderate and severe HIE. Cord blood pH (cutoff value, <6.9) and cord blood base deficit (cutoff value, >17 mM) increase the predictive values of protein S-100 and CK-BB. We conclude that elevated serum concentrations of protein S-100 and CK-BB reliably indicate moderate and severe HIE as early as 2 h after birth.

Metabolic changes after cardiac surgery

The metabolic changes that occur after cardiac surgery result from a complex interaction between the effects of surgery and extracorporeal circulation per se, the inflammatory response to surgical trauma and extracorporeal circulation, perioperative use of hypothermia, the cardiovascular and neuroendocrine responses characteristic to cardiac surgery, and the drugs and blood products used to support circulation during and after operation. These changes include among others increased oxygen consumption and energy expenditure and increased secretion of insulin, growth hormone, adrenocorticotrophic hormone, cortisol, epinephrine and norepinephrine. Other changes include decreased total-Trijodthyronine levels, hyperglycemia, hyperlactatemia, increased glutamate, aspartate and free fatty acid concentrations, hypokalemia, an increased production of inflammatory cytokines and increased consumption of complement and adhesion molecules. There is evidence that better control of metabolic abnormalities improves the patients' outcome.

Is there a relationship between cognitive dysfunction and systemic inflammatory response after cardiopulmonary bypass?

BACKGROUND

The systemic inflammatory reaction (SIR) is assumed to be one of the factors that causes cerebral dysfunction after cardiopulmonary bypass (CPB). The aim of the present study was to evaluate the relationship between the SIR and postoperative cognitive performance at 5 days and 3 months.

METHODS

One hundred patients undergoing coronary artery bypass grafting were studied. Inflammatory markers and markers of coagulation and fibrinolysis were determined at several time points during and after the operation. Correlation analysis between maximum levels of the different markers and early and late performance was performed.

RESULTS

No overall association was found between the maximum levels of the inflammatory markers and early and late function.

CONCLUSIONS

Notwithstanding limitations of statistical power established markers of systemic inflammatory reaction showed no relationship with outcome at 5-day or 3-month follow-up in this subset of patients.

Blood S-100 protein concentration in children undergoing cardiac surgery

OBJECTIVES

To investigate plasma levels of the betabeta isomer of S-100 protein and to assess the relationship between post-cardiopulmonary bypass (CPB) levels of this marker and a variety of perioperative and patient factors in children undergoing cardiac surgery.

DESIGN

Prospective study.

SETTING

University hospital.

PARTICIPANTS

Twenty-five children.

INTERVENTIONS

Blood samples (2 mL) for S-100 determinations were collected after the induction of anesthesia, 30 minutes after aortic cross-clamping, 1 hour after the termination of CPB, and 5 and 24 hours after the operation. Electroencephalogram activity was recorded, and neurologic examination was performed on all children 1 day before and 10 days after the operation. Lowest values of nasopharyngeal temperature, mean arterial pressure, arterial carbon dioxide tension (PaCO2), pH, and hematocrit during CPB were recorded.

MEASUREMENTS AND MAIN RESULTS

The overall change in S-100 during the study period was found to be statistically significant (p < 0.0001). Correlation between deltaS-100 and age (r = -0.45; p = 0.04), body surface area (r = -0.63; p = 0.002), nasopharyngeal temperature (r = -0.55; p = 0.01), and PaCO2 (r = -0.55; p = 0.009) was statistically significant in infants and children. Multivariate regression analysis indicated significant effects of PaCO2 and body surface area on deltaS-100 levels and area under the curve values.

CONCLUSION

In contrast to newborns, infants and older children showed prominent increases in S-100 protein concentration. Lack of pathologic electroencephalogram findings and neurologic signs in the postoperative period precludes the clinical use of S-100 protein concentration as a sensitive marker of cerebral injury.

Low serum S100β protein levels following coronary artery surgery with or without cardiopulmonary bypass

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.

AIM

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.