Serum biomarkers of neurologic injury in cardiac operations

Evaluation of the brain cellular damage during liver transplantations

Background

Neuroinflammation in patients undergoing major surgery can lead to neuronal damage, and neuronal damage can be detected through the measurement of biochemical markers of brain damage. S100 beta (S100 β), neuron-specific enolase (NSE), and glial fibrillary acidic protein (GFAP) levels are considered good biomarkers to detect brain damage that emerged with neurotoxicity.

Aim

To evaluate neuronal damage during liver transplantations.

Materials and Methods

After approval of the ethics committee and patient consents, preoperative and postoperative cognitive functions of 33 patients undergoing liver transplantation were measured using the Mini Mental State Examination (MMSE), whereas simultaneous neuronal damage was evaluated through the measurement of S100β, NSE, and GFAP levels.

Results

There was no statistically significant difference between preoperative and postoperative MMSE. There was a statistically significant decrease in postoperative GFAP (P < 0.05) and a statistically significant increase in NSE (P < 0.05) compared to preoperative values. The decrease in S100β (P > 0.05) level was statistically insignificant.

Conclusions

Neuroprotective approaches in anesthesia protocol protect patients from brain damage during liver transplantation and prevent the development of postoperative cognitive dysfunction. Since the significant increase in NSE levels during liver transplantations was deemed to have been associated with causes other than neuronal damage, NSE should not be evaluated as a marker of brain damage in these operations.

Difference in GFAP Levels in POCD and Non-POCD Patients After on Pump CABG

Introduction

On-pump, coronary artery bypass grafting (CABG) is the most common cause of postoperative cognitive dysfunction (POCD) after cardiac surgery. Previous studies showed that the incidence of POCD after cardiac surgery was 60%, higher than non-cardiac surgery with 11.7%. Glial fibrillary acid protein (GFAP) is one of the sensitive biomarkers of brain damage. Previous studies have found that elevated GFAP serum is associated with cognitive impairment. This study aims to measure the difference in GFAP levels in POCD and non-POCD patients after CABG on-pump surgery.

Methods

This study is a retrospective cohort design study. The data were obtained from 56 subjects undergoing elective CABG on the pump surgery enrolled into two groups consisting of 28 POCD as a case group and 28 non-POCD as a control group. In this study, the ELISA method measured the levels of GFAP biomarkers within 24 hours after surgery. After 72 hours, the patient received a MoCA-INA examination to determine cognitive impairment. Data analysis was carried out by SPSS 23.00 software.

Results

The mean age of patients in both groups was 60 years and was dominated by males (>85%). POCD patients were found to have a significantly longer duration of cardiopulmonary bypass (CPB) and cross-clamp surgery than non-POCD patients (p = 0.002 and p = 0.004). Postoperative GFAP levels in POCD patients were significantly higher than in non-POCD patients (12.95 ± 7.47 vs 3.80 ± 2.77, p < 0.001). There was a significant increase in GFAP levels compared with non-POCD (8.28 ± 7.24 vs -1.5 ± 3.03, p < 0.001). The area under the curve (AUC) value of GFAP against POCD was 0.887, cut-off GFAP 4.750 with a sensitivity of 92.9% and a specificity of 71.4%.

Conclusion

POCD patients had higher GFAP levels than non-POCD patients. There are differences in GFAP levels in patients with POCD and non-POCD post-CABG surgery.

Neurodegeneration and Vascular Burden on Cognition After Midlife: A Plasma and Neuroimaging Biomarker Study

Background and Objectives: Neurodegeneration and vascular burden are the two most common causes of post-stroke cognitive impairment. However, the interrelationship between the plasma beta-amyloid (Aβ) and tau protein, cortical atrophy and brain amyloid accumulation on PET imaging in stroke patients is undetermined. We aimed to explore: (1) the relationships of cortical thickness and amyloid burden on PET with plasma Aβ40, Aβ42, tau protein and their composite scores in stroke patients; and (2) the associations of post-stroke cognitive presentations with these plasma and neuroimaging biomarkers.

Methods: The prospective project recruited first-ever ischemic stroke patients around 3 months after stroke onset. The plasma Aβ40, Aβ42, and total tau protein were measured with the immunomagnetic reduction method. Cortical thickness was evaluated on MRI, and cortical amyloid plaque deposition was evaluated by ¹⁸F-florbetapir PET. Cognition was evaluated with Mini-Mental State Examination (MMSE), Geriatric Depression Scale (GDS), Dementia Rating Scale-2 (DRS-2).

Results: The study recruited 24 stroke patients and 13 normal controls. The plasma tau and tau*Aβ42 levels were correlated with mean cortical thickness after age adjustment. The Aβ42/Aβ40 ratio was correlated with global cortical ¹⁸F-florbetapir uptake value. The DRS-2 and GDS scores were associated with mean cortical thickness and plasma biomarkers, including Aβ42/Aβ40, tau, tau*Aβ42, tau/Aβ42, and tau/Aβ40 levels, in stroke patients.

Conclusion: Plasma Aβ, tau, and their composite scores were associated with cognitive performance 3 months after stroke, and these plasma biomarkers were correlated with corresponding imaging biomarkers of neurodegeneration. Further longitudinal studies with a larger sample size are warranted to replicate the study results.

Perioperative GABA Blood Concentrations in Infants with Cyanotic and Non-Cyanotic Congenital Heart Diseases

Perioperative stress detection in children with congenital heart disease (CHD), particularly in the brain, is still limited. Among biomarkers, γ-amino-aminobutyric acid (GABA) assessment in biological fluids appears to be promising for its regulatory action on the cardiovascular and cerebral systems. We aimed to investigate cyanotic (C) or non-cyanotic (N) CHD children for GABA blood level changes in the perioperative period. We conducted an observational study in 68 CHD infants (C: n = 33; N: n = 35) who underwent perioperative clinical, standard laboratory and monitoring parameter recordings and GABA assessment. Blood samples were drawn at five predetermined time-points before, during and after surgery. No significant perioperative differences were observed between groups in clinical and laboratory parameters. In C, perioperative GABA levels were significantly lower than N. Arterial oxygen saturation and blood concentration significantly differed between C and N children and correlated at cardiopulmonary by-pass (CPB) time-point with GABA levels. The present data showing higher hypoxia/hyperoxia-mediated GABA concentrations in C children suggest that they are more prone to perioperative cardiovascular and brain stress/damage. The findings suggest the usefulness of further investigations to detect the “optimal” oxygen concentration target in order to avoid the side effects associated with re-oxygenation during CPB.

MiRNA-124a: a Potential Biomarker for Neurological Deficits Following Cardiac Surgery in Pediatric Patients

Brain injury is a major source of patient morbidity after cardiac surgery in children. New early accurate biomarkers are needed for the diagnosis of patients at risk for cerebral postoperative damage. Specific circulating miRNAs have been found as suitable biomarkers for many diseases. We tested whether miRNA-124a reflects neurological injury in pediatric patients following heart surgery. Serum samples were obtained from 34 patients before and six hours after heart surgery. MiRNAs-124a was quantified by RQ-PCR. MiRNA-124a levels six hours after heart surgery correlated with the neurological outcome of the patients. In children with neurological deficits, miRNA-124a levels increased while in those with no neurological deficits the levels decreased. MiRNA-124a was able, at six hours after the operation, to identify patients who are at risk for the appearance of neurological deficits. Circulating miRNA-124a is a potential biomarker for the appearance of neurological deficits in pediatric patients following heart surgery. Graphical Abstract.

Intraoperative dexmedetomidine for prevention of postoperative delirium in elderly patients with mild cognitive impairment

OBJECTIVES

Delirium is the most common postoperative neurological complication and some evidence suggests that dexmedetomidine is associated with a decreased incidence of delirium. This study is designed to assess the effect of dexmedetomidine on postoperative delirium (POD) in elderly patients with mild cognitive impairment (MCI).

METHODS

Sixty geriatric patients with MCI were enrolled and ramdomly divided into two groups by a computer-generated randomisation sequence: dexmedetomidine group (D group) and normal saline group (C group). Patients in D group received a loading dose of 0.5 μg/kg dexmedetomidine over 10 minutes before anesthesia induction, followed by a continuous infusion of 0.4 μg·kg^-1·h^-1 until 30 minutes before the end of surgery; equal volume of normal saline was given in C group. Blood samples were extracted to detect the concentration of cytokines, including tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), heme oxygenase-1 (HO-1), matrix metalloproteinase-9 (MMP-9), and glial fibrillary acidic protein (GFAP) before anesthesia induction (T₁), before suture (T₂), and 30 minutes after surgery (T₃). Postoperative recovery times were recorded. Delirium was assessed with the 3-Minute Diagnostic Interview for confusion assessment method during the first 7 days postoperatively.

RESULTS

POD occurred in 10 (33.3%) of 30 patients in C group, and in 3 (10%) of 30 patients given dexmedetomidine (odds ratio [OR] 0.222, 95% CI 0.054-0.914; P = 0.028). The serum concentrations of TNF-α, MMP-9, and GFAP were significantly increased and IL-10 was decreased in the C group than in the D group at T₂ and T₃. No differences were observed between groups in the level of HO-1. Analysis using random-effect multivariable logistic regression indicated that POD was associated with GFAP (odds ratio [OR] 16.691, 95% CI 2.288-121.746; P = 0.005). The positive predictive ability of the multivariate logistic regression model tested by ROC analysis showed an area under the curve of 0.713 (95% CI, 0.584-0.842).

CONCLUSIONS

Dexmedetomidine can alleviate POD in elderly patients with MCI and may be related to reduce the neuroinflammation by lowering the permeability of blood-brain barrier.

Risk Factors for Delayed Neurocognitive Recovery According to Brain Biomarkers and Cerebral Blood Flow Velocity

Background and Objectives: The aim of this study is to identify risk factors for the development of delayed neurocognitive recovery (dNCR). Methods: 140 patients underwent neurocognitive evaluations (Adenbrooke, MoCa, trial making, and CAM test) and middle cerebral artery (MCA) blood flow velocity (BFV) measurements, one day before cardiac surgery. BFV was re-evaluated after anesthesia induction, before the beginning, middle, end, and after cardiopulmonary bypass (CPB) and postsurgery. To measure glial fibrillary acidic protein (GFAP) and neurofilament heavy chain (Nf-H), blood samples were collected after anesthesia induction, 24 and 48 h after the surgery. Neurocognitive evaluation was repeated 7-10 days after surgery. According to the results, patients were divided into two groups: with dNCR (dNCR group) and without dNCR (non-dNCR group). Results: 101 patients completed participation in this research. GFAP increased in both the non-dNCR group (p < 0.01) and in the dNCR group (p < 0.01), but there was no difference between the groups (after 24 h, p 0.342; after 48 h, p 0.273). Nf-H increased in both groups (p < 0.01), but there was no difference between them (after 24 h, p = 0.240; after 48 h, p = 0.597). MCA BFV was significantly lower in the dNCR group during the bypass (37.13 cm/s SD 7.70 versus 43.40 cm/s SD 9.56; p = 0.001) and after surgery (40.54 cm/s SD 11.21 versus 47.6 cm/s SD 12.01; p = 0.003). Results of neurocognitive tests correlated with CO₂ concentration (Pearson's r 0.40, p < 0.01), hematocrit (r 0.42, p < 0.01), MCA BFV during bypass (r 0.41, p < 0.01), and age (r -0.533, p < 0.01). The probability of developing dNCR increases 1.21 times with every one year of increased age (p < 0.01). The probability of developing dNCR increases 1.07 times with a decrease of BFV within 1 cm/s during bypass (p = 0.02). Conclusion: Risk factors contributing to dNCR among the tested patients were older age and middle cerebral artery blood flow velocity decrease during bypass.

Postoperative cognitive dysfunction after robot-assisted radical cystectomy (RARC) with cerebral oxygen monitoring an observational prospective cohort pilot study

Background

The incidence and risk factors of postoperative cognitive dysfunction (POCD) during robot-assisted radical cystectomy (RARC) in extreme Trendelenburg positioning and pneumoperitoneum are still controversial. The aim of this prospective observational study was to find the incidence rate as well as possible risk factors of POCD in RARC with cerebral oxygen monitoring.

Methods

Patients who underwent RARC and open abdominal surgery in horizontal positioning were included. Preoperative and postoperative arterial blood gas (ABG), S-100β, C-reactive protein (CRP), and cognitive dysfunction scales were tested. Also, we used Z score to analyze and comprehensively evaluate POCD. Measurements of heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), end-tidal CO₂ (etCO₂), and cerebral oxygen were immediately obtained after different time points during the surgery.

Results

Here, 24 and 23 patients were included in the RARC group and in the control group, respectively. The incidence of POCD didn’t have significant difference in RARC group (45.8%), in contrast to the control group (26.1%). The laboratory tests of s100β and CRP between two groups didn’t contain significant difference as well. As duration of Trendelenburg and pneumoperitoneum prolonged, the cerebral oxygen saturation in the RARC group increased, which didn’t cause excessive perfusion nevertheless (rSO₂<75%). We compared laboratory tests, age, education status, blood loss, and fluid input between POCD and non-POCD patients. A significant difference was found in the serum concentrations of CRP (72.59 ± 42.09 vs. 48.50 ± 26.53, P = 0.025) and age (69.20 ± 7.033 vs. 65.34 ± 5.228, P = 0.041).

Conclusion

RARC in extreme Trendelenburg positioning and pneumoperitoneum did not significantly increase the incidence of POCD and didn’t cause excessive perfusion. The inflammation marker CRP and age might be independent risk factors of POCD.

Trial registration

Clinicaltrials.gov with registration number NCT03372135. Registered 1 November 2017 (retrospectively registered).

Neuron-Specific Enolase and Matrix Metalloproteinase 9 Signal Perioperative Silent Brain Infarction During or After Transcatheter Aortic Valve Implantation

Magnetic resonance imaging (MRI) studies have consistently identified a high incidence of silent brain infarction (SBI) after cardiac intervention. The frequent occurrence, objective measurement and clinical sequelae of SBI have seen interest in their detection for both research and clinical purposes. However, MRI is expensive, time-consuming, unsafe in acutely-ill patients, and not always available, limiting its use as a routine screening tool. For this purpose, a blood biomarker of SBI would be the "Holy Grail." By performing targeted profiling of serologic biomarkers this study aimed to assess their potential as screening tools for perioperative SBI. This is a nested case-control study of 20 prospectively recruited patients undergoing transcatheter aortic valve implantation under general anesthesia. Clinical and diffusion-weighted MRI assessments were performed at baseline and on day 3 postprocedure to identify the presence (cases) or absence (controls) of new SBI. Blood was collected at baseline and 24, 48, and 72 hours postprocedure and analyzed for S100 calcium-binding protein B, neuron specific enolase (NSE), matrix metalloproteinase 9 (MMP 9), and glial fibrillary acidic protein. Best-fit polynomial curves using a smoothing model were generated for each biomarker and inferential testing at a predefined 24-hour postprocedure timepoint detected a significant difference for MMP 9 (72,435; SEM: 25,030; p = 0.027). Longitudinal regression revealed a statistically significant case-control difference for both NSE (mean: 10,747; SEM: 3,114) and MMP 9 (63,842; SEM: 16,173). In conclusion, NSE and MMP 9 are present in higher levels following SBI and warrant further investigation for their utility as screening tools.

Effects of Isolated Impaired Fasting Glucose on Brain Injury During Cardiac Surgery Under Cardiopulmonary Bypass

Objective: To evaluate the effects of isolated impaired fasting glucose (IIFG) on brain injury in patients undergoing cardiopulmonary bypass (CPB) surgery. Methods: Patients with rheumatic heart valve disease who underwent elective mitral valve replacement were included and divided into control and IIFG groups. Pre-, intra-, and postoperative blood glucose levels, serum insulin levels, insulin resistance index (HOMA-IR), lactic acid levels, and neuron-specific enolase (NSE) and S100B levels were measured. The cerebral oxygen extraction ratio (OER) was calculated. Cognitive function was assessed via the Mini-Mental State Examination (MMSE). Results: HOMA-IR levels were higher in the IIFG group than the control group 30 min after the beginning of CPB, at the termination of CPB, and 2 h after the termination of CPB. Cerebral OER and lactic acid increased intraoperatively in both groups, especially in the IIFG group. NSE and S100B levels were higher in the IIFG group than in the control group at the termination of CPB, 2 h after the termination of CPB, and at 24 h postoperatively. The MMSE scores did not significantly differ between the two groups. Delirium occurred in two patients in the IIFG group, and one in the control group. No other signs and symptoms of brain injuries were detected in either group. Conclusions: The increased postoperative NSE and S100B levels in the IIFG group compared with controls may be associated with severe insulin resistance and stress hyperglycemia. However, the IIFG group did not have clinical manifestations of brain injuries, including cognitive impairment.

The influence of carbon dioxide field flooding in mitral valve operations with cardiopulmonary bypass on S100ß level in blood plasma in the aging brain

Introduction

The risk of air microembolism during cardiopulmonary bypass (CPB) is high and influences the postoperative outcome, especially in elderly patients. The use of carbon dioxide (CO₂) atmosphere during cardiac surgery may reduce the risk of cerebral air microembolism. The aim of our study was to assess the influence of CO₂ field flooding on microembolism-induced brain damage assessed by the level of S100ß protein, regarded as a marker of brain damage.

Materials and methods

A group of 100 patients undergoing planned mitral valve operation through median sternotomy using standard CPB was recruited for the study. Echocardiography was performed prior to and after the CPB. CO₂ insufflation at 6 L/minute was conducted in the study group. Blood samples for S100ß protein analysis were collected after induction of anesthesia, 2 hours after aorta de-clamping, and 24 hours after operation.

Results

The S100ß level in blood plasma did not differ significantly between the study and the control group (0.13±0.08 µg/L, 1.12±0.59 µg/L, and 0.26±0.23 µg/L and 0.18±0.19 µg/L, 1.31±0.62 µg/L, and 0.23±0.12 µg/L, P=0.7, 0.14, and 0.78). The mean increase of the S100ß concentration was 13% lower in the group with CO₂ protection than in the control group (0.988 µg/L vs 1.125 µg/L), although statistically insignificant. Tricuspid valve annuloplasties (TVAs) had significant impact on the increase in S100ß concentration in the treatment group after 24 hours (TVA [−] 0.21±0.09 vs TVA [+] 0.42±0.42, P=0.05). In patients <60 years, there were significant differences in the S100ß level 2 and 24 hours after the procedure (1.59±0.682 µg/L vs 1.223±0.571 µg/L, P=0.048, and 0.363±0.318 µg/L vs 0.229±0.105 µg/L, P=0.036) as compared with younger patients.

Conclusion

The increase in S100ß concentration was lower in the group with CO₂ protection than in the control group. Age and an addition of TVA significantly influenced the level of S100ß concentration in the tests performed 2 hours after aortic clamp release.

Correlation among decreased regional cerebral oxygen saturation, blood levels of brain injury biomarkers, and cognitive disorder

Objective

This study was performed to investigate the correlation among decreased regional cerebral oxygen saturation (rSO₂), blood levels of brain injury biomarkers, and postoperative cognitive disorder (POCD) after cardiac surgery with cardiopulmonary bypass (CPB).

Methods

This prospective observational study included 59 patients undergoing coronary artery bypass graft surgery with CPB. All patients underwent neuropsychological tests (Mini Mental State Evaluation, Rey Auditory Verbal Learning Test, digit span test, digit symbol substitution test, and Schulte table) the day before and 10 days after the surgery. The blood levels of two brain injury biomarkers, neuron-specific enolase (NSE) and glial fibrillary acidic protein (GFAP), were measured before and 1 day after the surgery.

Results

The rSO₂ decreased during surgery in 21 (35%) patients. POCD was detected in 22 (37%) patients. After the surgery, no significant changes in the GFAP blood level occurred in any patients. No significant correlations were found among the decreased rSO₂, increased NSE blood level, and rate of POCD.

Conclusion

These results suggest that a decrease in rSO₂ during cardiac surgery is not necessarily related to the development of POCD or an increased blood level of the brain injury biomarker NSE.

S100B increases in cyanotic versus noncyanotic infants undergoing heart surgery and cardiopulmonary bypass (CPB)

AIMS

S100B has been proposed as a consolidated marker of brain damage in infants with congenital heart disease (CHD) undergoing cardiac surgery and cardiopulmonary bypass (CPB). The present study aimed to investigate whether S100B blood levels in the perioperative period differed in infants complicated or not by cyanotic CHD (CHDc) and correlated with oxygenation status (PaO₂).

METHODS

We conducted a case-control study of 48 CHD infants without pre-existing neurological disorders undergoing surgical repair and CPB. 24 infants were CHDc and 24 were CHD controls. Blood samples for S100B assessment were collected at six monitoring time-points: before the surgical procedure (T0), after sternotomy but before CPB (T1), at the end of the cross-clamp CPB phase (T2), at the end of CPB (T3), at the end of the surgical procedure (T4), at 24 h postsurgery (T5).

RESULTS

In the CHDc group, S100B multiples of median (MoM) were significantly higher (p < .05, for all) from T0 to T5. PaO₂ was significantly lower (p < .05, for all) in CHDc infants at T0-T1 and at T4 while no differences (p > .05, for all) were found at T2, T3, T5. Linear regression analysis showed a positive correlation between S100B MoM at T3 and PaO₂ (R = 0.84; p < .001).

CONCLUSIONS

The present data showing higher hypoxia/hyperoxia-mediated S100B concentrations in CHDc infants suggest that CHDc are more prone to perioperative brain stress/damage and suggest the usefulness of further investigations to detect the "optimal" PaO₂ target in order to avoid the side effects associated with reoxygenation during CPB.

Perfusion Pressure Cerebral Infarct (PPCI) trial - the importance of mean arterial pressure during cardiopulmonary bypass to prevent cerebral complications after cardiac surgery: study protocol for a randomised controlled trial

Background

Debilitating brain injury occurs in 1.6–5 % of patients undergoing cardiac surgery with cardiopulmonary bypass. Diffusion-weighted magnetic resonance imaging studies have reported stroke-like lesions in up to 51 % of patients after cardiac surgery. The majority of the lesions seem to be caused by emboli, but inadequate blood flow caused by other mechanisms may increase ischaemia in the penumbra or cause watershed infarcts. During cardiopulmonary bypass, blood pressure can be below the lower limit of cerebral autoregulation. Although much debated, the constant blood flow provided by the cardiopulmonary bypass system is still considered by many as appropriate to avoid cerebral ischaemia despite the low blood pressure.

Methods/design

The Perfusion Pressure Cerebral Infarct trial is a single-centre superiority trial with a blinded outcome assessment. The trial is randomising 210 patients with coronary vessel and/or valve disease and who are undergoing cardiac surgery with the use of cardiopulmonary bypass. Patients are stratified by age and surgical procedure and are randomised 1:1 to either an increased mean arterial pressure (70–80 mmHg) or ‘usual practice’ (40–50 mmHg) during cardiopulmonary bypass.

The cardiopulmonary bypass pump flow is fixed and set at 2.4 L/minute/m² body surface area plus 10–20 % in both groups.

The primary outcome measure is the volume of the new ischaemic cerebral lesions (in mL), expressed as the difference between a baseline, diffusion-weighted, magnetic resonance imaging scan and an equal scan conducted 3–6 days postoperatively. Secondary endpoints are the total number of new ischaemic cerebral lesions, postoperative cognitive dysfunction at discharge and 3 months postoperatively, diffuse cerebral injury evaluated by magnetic resonance spectroscopy and selected biochemical markers of cerebral injury.

The sample size will enable us to detect a 50 % reduction in the primary outcome measure in the intervention compared to the control group at a significance level of 0.05 and with a power of 0.80.

Discussion

This is the first clinical randomised study to evaluate whether the mean arterial pressure level during cardiopulmonary bypass influences the development of brain injuries that are detected by diffusion-weighted magnetic resonance imaging.

Trial registration

ClinicalTrials.gov, NCT02185885. Registered on 7 July 2014.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1373-6) contains supplementary material, which is available to authorized users.

Evidence of an association between brain cellular injury and cognitive decline after non-cardiac surgery

BACKGROUND

Postoperative cognitive dysfunction (POCD) is common after non-cardiac surgery, but the mechanism is unclear. We hypothesized that decrements in cognition 1 month after non-cardiac surgery would be associated with evidence of brain injury detected by elevation of plasma concentrations of S100β, neuron-specific enolase (NSE), and/or the brain-specific protein glial fibrillary acid protein (GFAP).

METHODS

One hundred and forty-nine patients undergoing shoulder surgery underwent neuropsychological testing before and then 1 month after surgery. Plasma was collected before and after anaesthesia. We determined the relationship between plasma biomarker concentrations and individual neuropsychological test results and a composite cognitive functioning score (mean Z-score).

RESULTS

POCD (≥-1.5 sd decrement in Z-score from baseline) was present in 10.1% of patients 1 month after surgery. There was a negative relationship between higher plasma GFAP concentrations and lower postoperative composite Z-scores {estimated slope=-0.14 [95% confidence interval (CI) -0.24 to -0.04], P=0.005} and change from baseline in postoperative scores on the Rey Complex Figure Test copy trial (P=0.021), delayed recall trial (P=0.010), and the Symbol Digit Modalities Test (P=0.004) after adjustment for age, sex, history of hypertension and diabetes. A similar relationship was not observed with S100β or NSE concentrations.

CONCLUSIONS

Decline in cognition 1 month after shoulder surgery is associated with brain cellular injury as demonstrated by elevated plasma GFAP concentrations.

Serum S-100β and NSE levels after off-pump versus on-pump coronary artery bypass graft surgery

Background

We aimed to evaluate serum levels of S-100 beta (S-100β) and neuron specific enolase (NSE) in patients with coronary heart disease (CHD) after off-pump versus on-pump coronary artery bypass graft (CABG) surgery.

Methods

The PubMed (~2013) and the Chinese Biomedical Database (CBM) (1982 ~ 2013) were searched without language restrictions. After extraction of relevant data from selected studies, meta-analyses were conducted using STATA software (Version 12.0, Stata Corporation, College Station, Texas USA). Possible sources of heterogeneity were examined through univariate and multivariate meta-regression analyses and verified by Monte Carlo Simulation.

Results

Eleven studies with a total of 411 CHD patients met the inclusion criteria. Our meta-analysis showed no significant difference in serum S-100β and NSE levels between the on-pump group and the off-pump group before surgery. In the on-pump group, there was a significant difference in serum S-100β levels of CHD patients between before and after surgery, especially within the first 24 h after surgery. Furthermore, in the on-pump group, there was a significant difference in serum NSE levels of CHD patients between before and after surgery, particularly at 0 h after surgery. In the off-pump group, there was an obvious difference in serum S-100β levels between before and after surgery, especially within 24 h after surgery. Our results also demonstrated that serum S-100β and NSE levels of CHD patients in the on-pump group were significantly higher than those of patients in the off-pump group, especially within 24 h after surgery.

Conclusions

Our findings provide empirical evidence that off-pump and on-pump CABG surgeries may increase serum S-100β and NSE levels in CHD patients, which was most prominent within 24 h after on-pump CABG surgery.

Rewarming Rate During Cardiopulmonary Bypass Is Associated With Release of Glial Fibrillary Acidic Protein

BACKGROUND

Rewarming from hypothermia during cardiopulmonary bypass (CPB) may compromise cerebral oxygen balance, potentially resulting in cerebral ischemia. The purpose of this study was to evaluate whether CPB rewarming rate is associated with cerebral ischemia assessed by the release of the brain injury biomarker glial fibrillary acidic protein (GFAP).

METHODS

Blood samples were collected from 152 patients after anesthesia induction and after CPB for the measurement of plasma GFAP levels. Nasal temperatures were recorded every 15 min. A multivariate estimation model for postoperative plasma GFAP level was determined that included the baseline GFAP levels, rewarming rate, CPB duration, and patient age.

RESULTS

The mean rewarming rate during CPB was 0.21° ± 0.11°C/min; the maximal temperature was 36.5° ± 1.0°C (range, 33.1°C to 38.0°C). Plasma GFAP levels increased after compared with before CPB (median, 0.022 ng/mL versus 0.035 ng/mL; p < 0.001). Rewarming rate (p = 0.001), but not maximal temperature (p = 0.77), was associated with higher plasma GFAP levels after CPB. In the adjusted estimation model, rewarming rate was positively associated with postoperative plasma log GFAP levels (coefficient, 0.261; 95% confidence intervals, 0.132 to 0.390; p < 0.001). Six patients (3.9%) experienced a postoperative stroke. Rewarming rate was higher (0.3° ± 0.09°C/min versus 0.2° ± 0.11°C/min; p = 0.049) in the patients with stroke compared with those without a stroke.

CONCLUSIONS

Rewarming rate during CPB was correlated with evidence of brain cellular injury documented with plasma GFAP levels. Modifying current practices of patient rewarming might provide a strategy to reduce the frequency of neurologic complications after cardiac surgery.

Hypotension After Cardiac Operations Based on Autoregulation Monitoring Leads to Brain Cellular Injury

BACKGROUND

Individualizing blood pressure targets could improve organ perfusion compared with current practices. In this study we assess whether hypotension defined by cerebral autoregulation monitoring vs standard definitions is associated with elevation in the brain-specific injury biomarker glial fibrillary acidic protein plasma levels (GFAP).

METHODS

Plasma GFAP levels were measured in 121 patients undergoing cardiac operations after anesthesia induction, at the conclusion of the operation, and on postoperative day 1. Cerebral autoregulation was monitored during the operation with the cerebral oximetry index, which correlates low-frequency changes in mean arterial pressure (MAP) and regional cerebral oxygen saturation. Blood pressure was recorded every 15 minutes in the intensive care unit. Hypotension was defined based on autoregulation data as an MAP below the optimal MAP (MAP at the lowest cerebral oximetry index) and based on standard definitions (systolic blood pressure decrement >20%, >30% from baseline, or <100 mm Hg, or both).

RESULTS

MAP (mean ± standard deviation) in the intensive care unit was 74 ± 7.3 mm Hg; optimal MAP was 78 ± 12.8 mm Hg (p = 0.008). The incidence of hypotension varied from 22% to 37% based on standard definitions but occurred in 54% of patients based on the cerebral oximetry index (p < 0.001). There was no relationship between standard definitions of hypotension and plasma GFAP levels, but MAP of less than optimal was positively related with postoperative day 1 GFAP levels (coefficient, 1.77; 95% confidence interval, 1.27 to 2.48; p = 0.001) after adjusting for GFAP levels at the conclusion of the operation and low cardiac output syndrome.

CONCLUSIONS

Individualizing blood pressure management using cerebral autoregulation monitoring may better ensure brain perfusion than current practice.

S100B protein as a screening tool for computed tomography findings after mild traumatic brain injury: Systematic review and meta-analysis

PRIMARY OBJECTIVE

To determine whether S100B protein in serum can predict intracranial lesions on computed tomography (CT) scan after mild traumatic brain injury (MTBI).

RESEARCH DESIGN

Systematic review and meta-analysis Methods and procedures: A literature search was conducted using Medline, Embase, Cochrane, Google Scholar, CINAHL, SUMSearch, Bandolier, Trip databases, bibliographies from identified articles and review article references. Eligible articles were defined as observational studies including patients with MTBI who underwent post-traumatic head CT scan and assessing the screening role of S100B protein.

MAIN OUTCOMES AND RESULTS

There was a significant positive association between S100B protein concentration and positive CT scan (22 studies, SMD = 1.92, 95% CI = 1.29-2.45, I² = 100%; p < 0.001). The pooled sensitivity and specificity values for a cut-point range = 0.16-0.20 µg L^-1 were 98.65 (95% CI = 95.53-101.77; I² = 0.0%) and 50.69 (95% CI = 40.69-60.69; I² = 76.3%), respectively. The threshold for serum S100B protein with 99.63 (95% CI = 96.00-103.25; I² = 0.0%) sensitivity and 46.94 (95% CI = 39.01-54.87; I² = 95.5%) specificity was > 0.20 µg L^-1.

CONCLUSIONS

After MTBI, serum S100B protein levels are significantly associated with the presence of intracranial lesions on CT scan. Measuring the protein could be useful in screening high risk MTBI patients and decreasing unnecessary CT examinations.

Shoulder surgery in the beach chair position is associated with diminished cerebral autoregulation but no differences in postoperative cognition or brain injury biomarker levels compared with supine positioning: the anesthesia patient safety foundation beach chair study

BACKGROUND

Although controversial, failing to consider the gravitational effects of head elevation on cerebral perfusion is speculated to increase susceptibility to rare, but devastating, neurologic complications after shoulder surgery in the beach chair position (BCP). We hypothesized that patients in the BCP have diminished cerebral blood flow autoregulation than those who undergo surgery in the lateral decubitus position (LDP). A secondary aim was to examine whether there is a relationship between patient positioning during surgery and postoperative cognition or serum brain injury biomarker levels.

METHODS

Patients undergoing shoulder surgery in the BCP (n = 109) or LDP (n = 109) had mean arterial blood pressure (MAP) and regional cerebral oxygen saturation (rScO2) monitored with near-infrared spectroscopy. A continuous, moving Pearson correlation coefficient was calculated between MAP and rScO2, generating the variable cerebral oximetry index (COx). When MAP is in the autoregulated range, COx approaches zero because there is no correlation between cerebral blood flow and arterial blood pressure. In contrast, when MAP is below the limit of autoregulation, COx is higher because there is a direct relationship between lower arterial blood pressure and lower cerebral blood flow. Thus, diminished autoregulation would be manifest as higher COx. Psychometric testing was performed before surgery and then 7 to 10 days and 4 to 6 weeks after surgery. A composite cognitive outcome was determined as the Z-score. Serum S100β, neuron-specific enolase, and glial fibrillary acidic protein were measured at baseline, after surgery, and on postoperative day 1.

RESULTS

After adjusting for age and history of hypertension, COx (P = 0.035) was higher and rScO2 lower (P < 0.0001) in the BCP group than in the LDP group. After adjusting for baseline composite cognitive outcome, there was no difference in Z-score 7 to 10 days (P = 0.530) or 4 to 6 weeks (P = 0.202) after surgery between the BCP and the LDP groups. There was no difference in serum biomarker levels between the 2 position groups

CONCLUSIONS

: Compared with patients in the LDP, patients undergoing shoulder surgery in the BCP are more likely to have higher COx indicating diminished cerebral autoregulation and lower rScO2. There were no differences in the composite cognitive outcome between the BCP and the LDP groups after surgery after accounting for baseline Z-score.

Surgical resilience: a review of resilience biomarkers and surgical recovery

BACKGROUND

Two distinct and large bodies of literature exist on resilience that are of potential interest for surgical outcomes. First is the literature on the impact of resilience on surgical recovery and wound-healing. Second is the literature on biomarkers for resilience, which largely focuses on neuropeptide Y (NPY), testosterone and dehydroepiandrosterone (DHEA). Despite this activity, there is a dearth of literature linking these two bodies of research by investigating biomarkers for surgical resilience and its impact on surgical recovery. This paper reviews both bodies of literature within the context of surgical recovery.

METHOD

Literature searches within Medline and Embase were conducted for studies and previous reviews of resilience biomarkers and for the impact of individual resilience on surgical recovery. Reference lists of the reviews were searched for additional papers. No systematic review is yet possible due to the novelty of the use of resilience biomarkers within a surgical context.

RESULTS

This is the first review to explore a potential link between resilience biomarkers and surgical recovery. There are a number of biomarkers that correlate with individual resilience levels and resilient individuals exhibit better recovery trajectories following surgery, suggesting a novel use of such biomarkers for the identification of "surgical resilience".

CONCLUSION

By identifying surgical resilience, there is potential for utilising these biomarkers as prognostic indicators of likely recovery trajectories from surgery, which in turn complement individualised peri-operative management.

The silent and apparent neurological injury in transcatheter aortic valve implantation study (SANITY): concept, design and rationale

Background

The incidence of clinically apparent stroke in transcatheter aortic valve implantation (TAVI) exceeds that of any other procedure performed by interventional cardiologists and, in the index admission, occurs more than twice as frequently with TAVI than with surgical aortic valve replacement (SAVR). However, this represents only a small component of the vast burden of neurological injury that occurs during TAVI, with recent evidence suggesting that many strokes are clinically silent or only subtly apparent. Additionally, insult may manifest as slight neurocognitive dysfunction rather than overt neurological deficits. Characterisation of the incidence and underlying aetiology of these neurological events may lead to identification of currently unrecognised neuroprotective strategies.

Methods

The Silent and Apparent Neurological Injury in TAVI (SANITY) Study is a prospective, multicentre, observational study comparing the incidence of neurological injury after TAVI versus SAVR. It introduces an intensive, standardised, formal neurologic and neurocognitive disease assessment for all aortic valve recipients, regardless of intervention (SAVR, TAVI), valve-type (bioprosthetic, Edwards SAPIEN-XT) or access route (sternotomy, transfemoral, transapical or transaortic). Comprehensive monitoring of neurological insult will also be recorded to more fully define and compare the neurological burden of the procedures and identify targets for harm minimisation strategies.

Discussion

The SANITY study undertakes the most rigorous assessment of neurological injury reported in the literature to date. It attempts to accurately characterise the insult and sustained injury associated with both TAVI and SAVR in an attempt to advance understanding of this complication and associations thus allowing for improved patient selection and procedural modification.

GFAP-BDP as an acute diagnostic marker in traumatic brain injury: results from the prospective transforming research and clinical knowledge in traumatic brain injury study

Reliable diagnosis of traumatic brain injury (TBI) is a major public health need. Glial fibrillary acidic protein (GFAP) is expressed in the central nervous system, and breakdown products (GFAP-BDP) are released following parenchymal brain injury. Here, we evaluate the diagnostic accuracy of elevated levels of plasma GFAP-BDP in TBI. Participants were identified as part of the prospective Transforming Research And Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) Study. Acute plasma samples (<24 h post-injury) were collected from patients presenting with brain injury who had CT imaging. The ability of GFAP-BDP level to discriminate patients with demonstrable traumatic lesions on CT, and with failure to return to pre-injury baseline at 6 months, was evaluated by the area under the receiver operating characteristic curve (AUC). Of the 215 patients included for analysis, 83% had mild, 4% had moderate, and 13% had severe TBI; 54% had acute traumatic lesions on CT. The ability of GFAP-BDP level to discriminate patients with traumatic lesions on CT as evaluated by AUC was 0.88 (95% confidence interval [CI], 0.84-0.93). The optimal cutoff of 0.68 ng/mL for plasma GFAP-BDP level was associated with a 21.61 odds ratio for traumatic findings on head CT. Discriminatory ability of unfavorable 6 month outcome was lower, AUC 0.65 (95% CI, 0.55-0.74), with a 2.07 odds ratio. GFAP-BDP levels reliably distinguish the presence and severity of CT scan findings in TBI patients. Although these findings confirm and extend prior studies, a larger prospective trial is still needed to validate the use of GFAP-BDP as a routine diagnostic biomarker for patient care and clinical research. The term "mild" continues to be a misnomer for this patient population, and underscores the need for evolving classification strategies for TBI targeted therapy. (ClinicalTrials.gov number NCT01565551; NIH Grant 1RC2 NS069409).