Impaired cerebral autoregulation and elevation in plasma glial fibrillary acidic protein level during cardiopulmonary bypass surgery for CHD

How to Define and Meet Blood Pressure Targets After Traumatic Brain Injury: A Narrative Review

BACKGROUND

Traumatic brain injury (TBI) poses a significant challenge to healthcare providers, necessitating meticulous management of hemodynamic parameters to optimize patient outcomes. This article delves into the critical task of defining and meeting continuous arterial blood pressure (ABP) and cerebral perfusion pressure (CPP) targets in the context of severe TBI in neurocritical care settings.

METHODS

We narratively reviewed existing literature, clinical guidelines, and emerging technologies to propose a comprehensive approach that integrates real-time monitoring, individualized cerebral perfusion target setting, and dynamic interventions.

RESULTS

Our findings emphasize the need for personalized hemodynamic management, considering the heterogeneity of patients with TBI and the evolving nature of their condition. We describe the latest advancements in monitoring technologies, such as autoregulation-guided ABP/CPP treatment, which enable a more nuanced understanding of cerebral perfusion dynamics. By incorporating these tools into a proactive monitoring strategy, clinicians can tailor interventions to optimize ABP/CPP and mitigate secondary brain injury.

DISCUSSION

Challenges in this field include the lack of standardized protocols for interpreting multimodal neuromonitoring data, potential variability in clinical decision-making, understanding the role of cardiac output, and the need for specialized expertise and customized software to have individualized ABP/CPP targets regularly available. The patient outcome benefit of monitoring-guided ABP/CPP target definitions still needs to be proven in patients with TBI.

CONCLUSIONS

We recommend that the TBI community take proactive steps to translate the potential benefits of personalized ABP/CPP targets, which have been implemented in certain centers, into a standardized and clinically validated reality through randomized controlled trials.

Cerebral autoregulation in paediatric and neonatal intensive care: A scoping review

Deranged cerebral autoregulation (CA) is associated with worse outcome in adult brain injury. Strategies for monitoring CA and maintaining the brain at its 'best CA status' have been implemented, however, this approach has not yet developed for the paediatric population. This scoping review aims to find up-to-date evidence on CA assessment in children and neonates with a view to identify patient categories in which CA has been measured so far, CA monitoring methods and its relationship with clinical outcome if any. A literature search was conducted for studies published within 31st December 2022 in 3 bibliographic databases. Out of 494 papers screened, this review includes 135 studies. Our literature search reveals evidence for CA measurement in the paediatric population across different diagnostic categories and age groups. The techniques adopted, indices and thresholds used to assess and define CA are heterogeneous. We discuss the relevance of available evidence for CA assessment in the paediatric population. However, due to small number of studies and heterogeneity of methods used, there is no conclusive evidence to support universal adoption of CA monitoring, technique, and methodology. This calls for further work to understand the clinical impact of CA monitoring in paediatric and neonatal intensive care.

Determining Optimal Mean Arterial Blood Pressure Based on Cerebral Autoregulation in Children after Cardiac Surgery

To evaluate the feasibility of continuous determination of the optimal mean arterial blood pressure (opt-MAP) according to cerebral autoregulation and to describe the opt-MAP, the autoregulation limits, and the time spent outside these limits in children within 48 h of cardiac surgery. Cerebral autoregulation was assessed using the correlation coefficient (COx) between cerebral oxygenation and MAP in children following cardiac surgery. Plots depicting the COx according to the MAP were used to determine the opt-MAP using weighted multiple time windows. For each patient, we estimated (1) the time spent with MAP outside the autoregulation limits and (2) the burden of deviation, defined as the area between the MAP curve and the autoregulation limits when the MAP was outside these limits. Fifty-one patients with a median age of 7.1 (IQR 0.7-52.0) months old were included. The opt-MAP was calculated for 94% (IQR 90-96) of the monitored time. The opt-MAP was significantly lower in neonates < 1 month old. The patients spent 24% (18-31) of the time outside of the autoregulation limits, with no significant differences between age groups. Continuous determination of the opt-MAP is feasible in children within the first 48 h following cardiac surgery.

Utility of Brain Injury Biomarkers in Children With Congenital Heart Disease Undergoing Cardiac Surgery

BACKGROUND

Congenital heart disease (CHD) affects roughly 40,000 children annually. Despite advancements, children undergoing surgery for CHD are at an increased risk for adverse neurological outcomes. At present, there is no gold standard for the diagnosis of cerebral injury during the perioperative period.

OBJECTIVE

To determine the utility of brain injury biomarkers in children undergoing cardiac surgery.

METHODS

We searched PUBMED, EMBASE, LILACS, EBSCO, ClinicalTrials.gov, Cochrane Databases, and OVID interface to search MEDLINE through July 2021 and assessed the literature following the snowball method. The search terms used were "congenital heart disease," "cardiopulmonary bypass," "biomarkers," "diagnosis," "prognosis," and "children." No language or publication date restrictions were used. Papers studying inflammatory and imaging biomarkers were excluded. The risk of bias, strengths, and limitations of the study were reported. Study was registered in PROSPERO ID: CRD42021258385.

RESULTS

A total of 1449 articles were retrieved, and 27 were included. Eight neurological biomarkers were examined. Outcomes assessed included prognosis of poor neurological outcome, mortality, readmission, and diagnosis of brain injury. Results from these studies support that significant perioperative elevations in brain injury biomarkers in cerebrospinal fluid and serum, including S100B, GFAP, NSE, and activin A, may be diagnostic of real-time brain injury and serve as an independent predictor of adverse neurological outcomes in patients with CHD undergoing cardiopulmonary bypass.

CONCLUSIONS

There are limited homogeneous data in the field, limiting the generalizability and comparability of the results. Further large-scale longitudinal studies addressing neurological biomarkers in children undergoing CHD corrective surgery are required to support the routine use of neuronal biomarkers in this population.

A pilot study: Comparing a novel noninvasive measure of cerebrovascular stability index with an invasive measure of cerebral autoregulation in neonates with congenital heart disease

Infants with congenital heart disease (CHD) may have impaired cerebral autoregulation (CA) associated with cerebral fractional tissue oxygen extraction (FTOE). We conducted a pilot study in nine CHD neonates to validate a noninvasive CA measure, cerebrovascular stability index (CSI), by eliciting responses to postural tilts. We compared CSI to an invasive measure of CA and to FTOE collected during tilts (FTOESpot). FTOESpot correlated with CSI, as did the change in FTOE during tilts, but CSI's correlation with impaired CA did not reach significance. Larger trials are indicated to validate CSI, allowing for noninvasive CA measurements and measurements in outpatient settings.

Cerebral Autoregulation Status in Relation to Brain Injury on Electroencephalogram and Magnetic Resonance Imaging in Children Following Cardiac Surgery

Background Disturbed cerebral autoregulation has been reported in children with congenital heart disease before and during cardiopulmonary bypass surgery, but not after. We sought to characterize the cerebral autoregulation status in the early postoperative period in relation to perioperative variables and brain injuries. Methods and Results A prospective and observational study was conducted in 80 patients in the first 48 hours following cardiac surgery. Cerebral oximetry/pressure index (COPI) was retrospectively calculated as a moving linear correlation coefficient between mean arterial blood pressure and cerebral oxygen saturation. Disturbed autoregulation was defined as COPI >0.3. Correlations of COPI with demographic and perioperative variables as well as brain injuries on electroencephalogram and magnetic resonance imaging and early outcomes were analyzed. Thirty-six (45%) patients had periods of abnormal COPI for 7.81 hours (3.38 hours) either at hypotension (median <45 mm Hg) or hypertension (median >90 mm Hg) or both. Overall, COPI became significantly lower over time, suggesting improved autoregulatory status during the 48 postoperative hours. All of the demographic and perioperative variables were significantly associated with COPI, which in turn was associated with the degree of brain injuries and early outcomes. Conclusions Children with congenital heart disease following cardiac surgery often have disturbed autoregulation. Cerebral autoregulation is at least partly the underlying mechanism of brain injury in those children. Careful clinical management to manipulate the related and modifiable factors, particularly arterial blood pressure, may help to maintain adequate cerebral perfusion and reduce brain injury early after cardiopulmonary bypass surgery. Further studies are warranted to determine the significance of impaired cerebral autoregulation in relation to long-term neurodevelopment outcomes.

Identifying the optimal blood pressure for cerebral autoregulation in infants after cardiac surgery by monitoring cerebrovascular reactivity-A pilot study

BACKGROUND

Advances in the treatment of pediatric congenital heart disease have increased survival rates. Despite efforts to prevent neurological injury, many patients suffer from impaired neurodevelopmental outcomes. Compromised cerebral autoregulation can increase the risk of brain injury following pediatric cardiac surgery with cardiopulmonary bypass. Monitoring autoregulation and maintaining adequate cerebral blood flow can help prevent neurological injury.

AIMS

Our objective was to evaluate autoregulation parameters and to define the optimal blood pressure as well as the lower and upper blood pressure limits of autoregulation.

METHODS

Autoregulation was monitored prospectively in 36 infants after cardiopulmonary bypass surgery for congenital heart defects between January and December 2019. Autoregulation indices were calculated by correlating invasive arterial blood pressure, cortical oxygen saturation, and relative tissue hemoglobin levels with near-infrared spectroscopy parameters.

RESULTS

The mean patient age was 4.1 ± 2.8 months, and the mean patient weight was 5.2 ± 1.8 kg. Optimal mean arterial pressure could be identified in 88.9% of patients via the hemoglobin volume index and in 91.7% of patients via the cerebral oxygenation index, and a lower limit of autoregulation could be found in 66.7% and 63.9% of patients, respectively. No significant changes in autoregulation indices at the beginning or end of the monitoring period were observed. In 76.5% ± 11.1% and 83.8% ± 9.9% of the 8 and 16 h monitoring times, respectively, the mean blood pressure was inside the range of intact autoregulation (below in 21.5% ± 25.4% and 11.3% ± 16.5% and above in 8.7% ± 10.4% and 6.0% ± 11.0%, respectively). The mean optimal blood pressure was 57.4 ± 8.7 mmHg and 58.2 ± 7.9 mmHg and the mean lower limit of autoregulation was 48.8 ± 8.3 mmHg and 45.5 ± 6.7 mmHg when generated via the hemoglobin volume index and cerebral oxygenation index, respectively.

CONCLUSIONS

Postoperative noninvasive autoregulation monitoring after cardiac surgery in children can be reliably and safely performed using the hemoglobin volume index and cerebral oxygenation index and provides robust data. This monitoring can be used to identify individual hemodynamic targets to optimize autoregulation, which differs from those recommended in the literature. Further evaluation of this subject is needed.

Age Difference of the Relationship Between Cerebral Oxygen Saturation and Physiological Parameters in Pediatric Cardiac Surgery with Cardiopulmonary Bypass: Analysis Using the Random-Effects Model

Recently, monitoring of cerebral oxygen saturation (ScO₂) has become widespread in pediatric cardiac surgery. Our previous study reported that mean blood pressure (mBP) was the major contributor to ScO₂ throughout cardiac surgery with cardiopulmonary bypass (CPB) in children weighing under 10 kg. We speculated that this result might be attributable to incomplete cerebral autoregulation in such young children. Accordingly, our hypothesis is that the relationship between ScO₂ and the physiological parameters may change according to the growth of the children. ScO₂ was measured with an INVOS 5100C (Somanetics, Troy, MI). Random-effects analysis was employed with ScO₂ as a dependent variable, and seven physiological parameters (mBP, central venous pressure, nasopharyngeal temperature, SaO₂, hematocrit, PaCO₂, and pH) were entered as independent covariates. The analysis was performed during the pre-CPB, CPB, and post-CPB periods by dividing the patients into two groups: infants (Infant Group) and children who were more than 1 year old (Child Group). The Infant and Child Groups consisted of 28 and 21 patients. In the random-effects analysis, mBP was the major contributor to ScO₂ during CPB in both groups. During the pre-CPB period, the effect of mBP was strongest in the Infant group. However, its effect was second to that of SaO₂ in the Child Group. During the post-CPB period, SaO₂ and mBP still affected ScO₂ in the Infant group. However, the dominant contributors were unclear in the Child Group. Cerebral autoregulation may be immature in infants. In addition, it may be impaired during CPB even after 1 year of age.

Effects of circulatory arrest and cardiopulmonary bypass on cerebral autoregulation in neonatal swine

BACKGROUND

Cerebral autoregulation mechanisms help maintain adequate cerebral blood flow (CBF) despite changes in cerebral perfusion pressure. Impairment of cerebral autoregulation, during and after cardiopulmonary bypass (CPB), may increase risk of neurologic injury in neonates undergoing surgery. In this study, alterations of cerebral autoregulation were assessed in a neonatal swine model probing four perfusion strategies.

METHODS

Neonatal swine (n = 25) were randomized to continuous deep hypothermic cardiopulmonary bypass (DH-CPB, n = 7), deep hypothermic circulatory arrest (DHCA, n = 7), selective cerebral perfusion (SCP, n = 7) at deep hypothermia, or normothermic cardiopulmonary bypass (control, n = 4). The correlation coefficient (LDx) between laser Doppler measurements of CBF and mean arterial blood pressure was computed at initiation and conclusion of CPB. Alterations in cerebral autoregulation were assessed by the change between initial and final LDx measurements.

RESULTS

Cerebral autoregulation became more impaired (LDx increased) in piglets that underwent DH-CPB (initial LDx: median 0.15, IQR [0.03, 0.26]; final: 0.45, [0.27, 0.74]; p = 0.02). LDx was not altered in those undergoing DHCA (p > 0.99) or SCP (p = 0.13). These differences were not explained by other risk factors.

CONCLUSIONS

In a validated swine model of cardiac surgery, DH-CPB had a significant effect on cerebral autoregulation, whereas DHCA and SCP did not.

IMPACT

Approximately half of the patients who survive neonatal heart surgery with cardiopulmonary bypass (CPB) experience neurodevelopmental delays. This preclinical investigation takes steps to elucidate and isolate potential perioperative risk factors of neurologic injury, such as impairment of cerebral autoregulation, associated with cardiac surgical procedures involving CPB. We demonstrate a method to characterize cerebral autoregulation during CPB pump flow changes in a neonatal swine model of cardiac surgery. Cerebral autoregulation was not altered in piglets that underwent deep hypothermic circulatory arrest (DHCA) or selective cerebral perfusion (SCP), but it was altered in piglets that underwent deep hypothermic CBP.

Serum brain injury biomarkers are gestationally and post-natally regulated in non-brain injured neonates

BACKGROUND

To determine the association of gestational age (GA) and day of life (DOL) with the circulating serum concentration of six brain injury-associated biomarkers in non-brain injured neonates born between 23 and 41 weeks' GA.

METHODS

In a multicenter prospective observational cohort study, serum CNS-insult, inflammatory and trophic proteins concentrations were measured daily in the first 7 DOL.

RESULTS

Overall, 3232 serum samples were analyzed from 745 enrollees, median GA 32.3 weeks. BDNF increased 3.7% and IL-8 increased 8.9% each week of gestation. VEGF, IL-6, and IL-10 showed no relationship with GA. VEGF increased 10.8% and IL-8 18.9%, each DOL. IL-6 decreased by 15.8% each DOL. IL-10 decreased by 81.4% each DOL for DOL 0-3. BDNF did not change with DOL. Only 49.67% of samples had detectable GFAP and 33.15% had detectable NRGN. The odds of having detectable GFAP and NRGN increased by 53% and 11%, respectively, each week after 36 weeks' GA. The odds of having detectable GFAP and NRGN decreased by 15% and 8%, respectively, each DOL.

CONCLUSIONS

BDNF and IL-8 serum concentrations vary with GA. VEGF and interleukin concentrations are dynamic in the first week of life, suggesting circulating levels should be adjusted for GA and DOL for clinically relevant assessment of brain injury.

IMPACT

Normative data of six brain injury-related biomarkers is being proposed. When interpreting serum concentrations of brain injury biomarkers, it is key to adjust for gestational age at birth and day of life during the first week to correctly assess for clinical brain injury in neonates. Variation in levels of some biomarkers may be related to gestational and postnatal age and not necessarily pathology.

Cerebral Autoregulation in Non-Brain Injured Patients: A Systematic Review

Introduction: Cerebral autoregulation (CA) plays a fundamental role in the maintenance of adequate cerebral blood flow (CBF). CA monitoring, through direct and indirect techniques, may guide an appropriate therapeutic approach aimed at improving CBF and reducing neurological complications; so far, the role of CA has been investigated mainly in brain-injured patients. The aim of this study is to investigate the role of CA in non-brain injured patients.

Methods: A systematic consultation of literature was carried out. Search terms included: “CA and sepsis,” “CA and surgery,” and “CA and non-brain injury.”

Results: Our research individualized 294 studies and after screening, 22 studies were analyzed in this study. Studies were divided in three groups: CA in sepsis and septic shock, CA during surgery, and CA in the pediatric population. Studies in sepsis and intraoperative setting highlighted a relationship between the incidence of sepsis-associated delirium and impaired CA. The most investigated setting in the pediatric population is cardiac surgery, but the role and measurement of CA need to be further elucidated.

Conclusion: In non-brain injured patients, impaired CA may result in cognitive dysfunction, neurological damage, worst outcome, and increased mortality. Monitoring CA might be a useful tool for the bedside optimization and individualization of the clinical management in this group of patients.

Regulation of the Cerebral Circulation During Development

The cerebral microcirculation undergoes dynamic changes in parallel with the development of neurons, glia, and their energy metabolism throughout gestation and postnatally. Cerebral blood flow (CBF), oxygen consumption, and glucose consumption are as low as 20% of adult levels in humans born prematurely but eventually exceed adult levels at ages 3 to 11 years, which coincide with the period of continued brain growth, synapse formation, synapse pruning, and myelination. Neurovascular coupling to sensory activation is present but attenuated at birth. By 2 postnatal months, the increase in CBF often is disproportionately smaller than the increase in oxygen consumption, in contrast to the relative hyperemia seen in adults. Vascular smooth muscle myogenic tone increases in parallel with developmental increases in arterial pressure. CBF autoregulatory response to increased arterial pressure is intact at birth but has a more limited range with arterial hypotension. Hypoxia-induced vasodilation in preterm fetal sheep with low oxygen consumption does not sustain cerebral oxygen transport, but the response becomes better developed for sustaining oxygen transport by term. Nitric oxide tonically inhibits vasomotor tone, and glutamate receptor activation can evoke its release in lambs and piglets. In piglets, astrocyte-derived carbon monoxide plays a central role in vasodilation evoked by glutamate, ADP, and seizures, and prostanoids play a large role in endothelial-dependent and hypercapnic vasodilation. Overall, homeostatic mechanisms of CBF regulation in response to arterial pressure, neuronal activity, carbon dioxide, and oxygenation are present at birth but continue to develop postnatally as neurovascular signaling pathways are dynamically altered and integrated. © 2021 American Physiological Society. Compr Physiol 11:1-62, 2021.

Age-Related Changes in Cerebral Hemodynamics in Children Undergoing Congenital Cardiac Surgery: A Prospective Observational Study

OBJECTIVE

To explore age-related cerebral hemodynamic characteristics before and after pediatric cardiac surgery.

DESIGN

Prospective observational study.

SETTING

Single-center study based at a tertiary care center in Shanghai, China.

PATIENTS

Fifty-three children with congenital heart disease (CHD) aged zero-to-six years undergoing cardiac surgery with cardiopulmonary bypass were enrolled, and 44 children finally were analyzed.

INTERVENTION

Cerebral hemodynamics were measured by transcranial color-coded duplex sonography in the right temporal window before and after surgery. The resistance index (RI), pulsatility index (PI), and cerebral blood flow velocity (CBFV), including time average maximum flow velocity (V_tamax), mean blood flow velocity (V_mean), and the peak systolic flow velocity (V_peak), of the right middle cerebral artery (MCA) and regional cerebral oxygen saturation (rScO₂) of the right frontal lobe were measured and analyzed. Heart rate and mean arterial pressure were also recorded during ultrasound.

MEASUREMENTS AND MAIN RESULTS

RI and PI decreased exponentially with age before and after cardiac surgery. While PI remained unchanged after cardiac surgery, RI was significantly reduced. Furthermore, RI reduction after cardiac surgery was more significant in children >18 months compared to those ≤18 months. CBFV of the right MCA also showed exponential increase with age, but rScO₂ linearly increased. Cardiac surgery significantly changed the cerebral hemodynamics, but it did not affect rScO₂ in children regardless of age.

CONCLUSIONS

Age-related cerebral hemodynamic changes exist in children with CHD. Cardiopulmonary bypass surgery led to greater cerebrovascular dilation in children aged ≤18 months than those >18 months.

The Relationships of Cerebral and Somatic Oxygen Saturation with Physiological Parameters in Pediatric Cardiac Surgery with Cardiopulmonary Bypass: Analysis Using the Random-Effects Model

Recently, tissue oxygenation in pediatric heart surgery is measured by using near-infrared spectroscopy. Monitoring of cerebral oxygen saturation (ScO₂) is most common but that of somatic tissue oxygen saturation (SrO₂) is also gradually becoming widespread. However, the value of their monitoring is not well established. One of the reasons for this may be that the physiological factors affecting ScO₂ and SrO₂ have not been sufficiently clarified. Accordingly, we prospectively observed the changes in ScO₂ and SrO₂ simultaneously throughout cardiac surgery with cardiopulmonary bypass (CPB) in children weighing under 10 kg and evaluated their relationships with physiological parameters by using the random-effects model. ScO₂ and SrO₂ were measured with an INVOS 5100C (Somanetics, Troy, MI, USA). The random-effects analysis was applied for ScO₂ and SrO₂, as dependent variables, and seven physiological parameters (mean blood pressure, central venous pressure, rectal temperature, SaO₂, hematocrit PaCO₂, and pH) were entered as independent covariates. The analysis was performed during the pre-CPB, CPB, and post-CPB periods. Next, the same analysis was performed by dividing the patients into univentricular and biventricular physiological types. Forty-one children were evaluated. Through the whole surgical period, ScO₂ correlated strongly with mean blood pressure regardless of the physiological type. On the other hand, the contribution of mean blood pressure to SrO₂ was weak and various other parameters were related to SrO₂ changes. Thus, the physiological parameters affecting ScO₂ and SrO₂ were rather different. Accordingly, the significance of monitoring of cerebral and somatic tissue oxygen saturation in pediatric cardiac surgery should be further evaluated.

Pharmacologic Control of Blood Pressure in Infants and Children

Alterations in blood pressure are common during the perioperative period in infants and children. Perioperative hypertension may be the result of renal failure, volume overload, or activation of the sympathetic nervous system. Concerns regarding end-organ effects or postoperative bleeding may mandate regulation of blood pressure. During the perioperative period, various pharmacologic agents have been used for blood pressure control including sodium nitroprusside, nitroglycerin, β-adrenergic antagonists, fenoldopam, and calcium channel antagonists. The following manuscript outlines the commonly used pharmacologic agents for perioperative BP including dosing regimens and adverse effect profiles. Previously published clinical trials are discussed and efficacy in the perioperative period reviewed.

Cerebral Autoregulation in Sick Infants: Current Insights

Cerebrovascular autoregulation is the ability to maintain stable cerebral blood flow within a range of cerebral perfusion pressures. When cerebral perfusion pressure is outside the limits of effective autoregulation, the brain is subjected to hypoperfusion or hyperperfusion, which may cause vascular injury, hemorrhage, and/or hypoxic white matter injury. Infants born preterm, after fetal growth restriction, with congenital heart disease, or with hypoxic-ischemic encephalopathy are susceptible to a failure of cerebral autoregulation. Bedside assessment of cerebrovascular autoregulation would offer the opportunity to prevent brain injury. Clinicians need to know which patient populations and circumstances are associated with impaired/absent cerebral autoregulation.

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.

The influence of blood flow velocity changes to postoperative cognitive dysfunction development in patients undergoing heart surgery with cardiopulmonary bypass

BACKGROUND

The aim of this study was to compare blood flow velocity changes in the middle cerebral artery before, during and after heart surgery with cardiopulmonary bypass for patients with and without postoperative cognitive dysfunction.

MATERIALS AND METHODS

A total of 100 patients, undergoing elective coronary artery bypass grafting or/and valve surgery enrolled in the study. A neurocognitive test evaluation included Adenbrooke, Mini-Mental State Examination and Trial Making test before and 7-10 days after surgery. Middle cerebral artery mean blood flow velocity was evaluated 1 day before the surgery, after anaesthesia induction, before cardiopulmonary bypass, at the beginning, ending and after cardiopulmonary bypass, and post surgery in intensive care unit. Blood samples for glial fibrillary acidic protein were measured after anaesthesia induction, 24 hours and 48 hours after surgery. According to neurocognitive tests results patients were divided in to two groups: patients with and without postoperative cognitive dysfunction.

RESULTS

Of the 100, 86 patients completed investigation. After induction, blood flow velocity of the middle cerebral artery was lower in postoperative cognitive dysfunction group (41.2; min 27.91, max 49.47) than in the H group (41.2, min 21.9, max 84.3) p = 0.034, and during cardiopulmonary bypass, blood flow velocity of the middle cerebral artery was lower in the postoperative cognitive dysfunction group (37.35, min 26.6, max 44.02) than the H group (42.3, min 20.1, max 86.5), p = 0.001. After the surgery, blood flow velocity of the middle cerebral artery was lower in the postoperative cognitive dysfunction group (40.7, min 29.7, max 50.4) than in the H group (45.3, min 34.12, max 59.88), p = 0.05. Results of cognitive tests had weak correlation (rho, 0.391) with middle cerebral artery's blood flow velocity after anaesthesia induction (p = 0.001) and during bypass (p = 0.018). The receiver operating characteristic analysis showed that the blood flow velocity of the middle cerebral artery during bypass (area under the curve = 0.735) was a fair predictor for postoperative cognitive dysfunction (p = 0.001). No significant correlations were found among glial fibrillary acidic protein, middle cerebral artery blood flow velocity, and cognitive tests results.

CONCLUSION

Middle cerebral artery's blood flow velocity was decreased after anaesthesia induction and during cardiopulmonary bypass for patients with postoperative cognitive dysfunction comparing with their blood flow velocity preoperatively. Blood flow velocity during bypass has diagnostic value for postoperative cognitive dysfunction. Brain biomarker glial fibrillary acidic protein is not helpful in diagnosing postoperative cognitive dysfunction.

Near-Infrared Spectroscopy in Pediatric Congenital Heart Disease

Near-infrared spectroscopy (NIRS) is widely used to monitor tissue oxygenation in the pediatric cardiac surgical population. Clinicians who use NIRS must understand the underlying measurement principles in order to interpret and use this monitoring modality appropriately. The aims of this narrative review are to provide a brief overview of NIRS technology, discuss the normative and critical values of cerebral and somatic tissue oxygen saturation and the interpretation of these values, present the clinical studies (and their limitations) of NIRS as a perioperative monitoring modality in the pediatric congenital heart disease population, and introduce the emerging and future applications of NIRS.

The Year in Review: Anesthesia for Congenital Heart Disease 2018

This review article surveys the published literature from January 2018 to March 2019. Three themes were identified and articles were selected based on their originality and interest to anesthesiologists caring for patients with congenital heart disease.