Benefit of neurophysiologic monitoring for pediatric cardiac surgery

Cerebral blood flow dynamics during cardiac surgery in infants

BACKGROUND

In this pilot study, we investigated continuous cerebral blood flow velocity measurements to explore cerebrovascular hemodynamics in infants with congenital heart disease undergoing cardiac surgery.

METHODS

A non-invasive transfontanellar cerebral Doppler monitor (NeoDoppler) was used to monitor 15 infants (aged eight days to nine months) during cardiac surgery with cardiopulmonary bypass. Numerical and visual analyses were conducted to assess trends and events in Doppler measurements together with standard monitoring equipment. The mean flow index, calculated as the moving Pearson correlation between mean arterial pressure and time averaged velocity, was utilized to evaluate dynamic autoregulation. Two levels of impaired autoregulation were defined (Mean flow index >0.3/0.45), and percentage of time above these limits were calculated.

RESULTS

High quality recordings were achieved during 90.6% of the monitoring period. There was a significant reduction in time averaged velocity in all periods of cardiopulmonary bypass. All patients showed a high percentage of time with impaired dynamic autoregulation, with Mean flow index >0.3 and 0.45: 73.71% ± 9.06% and 65.16% ± 11.27% respectively. Additionally, the system promptly detected hemodynamic events.

CONCLUSION

Continuous transfontanellar cerebral Doppler monitoring could become an additional tool in enhancing cerebral monitoring in infants during cardiac surgery.

IMPACT

This pilot study demonstrates the feasibility of continuous transfontanellar Doppler monitoring of cerebral blood flow velocities during cardiac surgery in infants. It also demonstrates a high proportion of time with impaired cerebral autoregulation during cardiac surgery based on the Mean flow index. Continuous transfontanellar Doppler could become a useful tool to improve cerebral monitoring and provide new pathophysiological insight.

Neurological injury in pediatric heart disease: A review of developmental and acquired risk factors and management considerations

Medical and surgical advancements have improved survival in children with acquired and congenital heart disease (CHD), but the burden of neurological morbidity is high. Brain disorders associated with CHD include white matter injury, stroke, seizure, and neurodevelopmental delays. While genetics and disease-specific factors play a substantial role in early brain injury, therapeutic management of the heart disease intensifies the risk. There is a growing interest in understanding how to reduce brain injury and improve neurodevelopmental outcomes in cardiac diseases. Pediatric neurologists serve a vital role in care teams managing these complex patients, providing interpretation of neuromonitoring and imaging, managing neurologic emergencies, assisting with neuro prognostication, and identifying future research aims.

Intraoperative Regional Cerebral Oxygenation During Pediatric Thoracoscopic Surgery: A Systematic Review

Background: Ventilating a pediatric patient during thoracoscopy is challenging. Few studies have highlighted the impact of capnothorax in children by measuring regional cerebral oxygen saturation (rcSO2) with near infrared spectroscopy. In this systematic review, we aimed to summarize the data from relevant studies and assess whether thoracoscopy in children is associated with intraoperative pathological cerebral desaturation. Methods: The authors systematically searched four databases for relevant studies on the measurement of rcSO2 during pediatric thoracoscopic procedures. The primary outcome was the proportion of patients with pathological desaturation, that is, >20% decline in the intraoperative rcSO2. Risk of bias among the included studies was estimated using the Newcastle-Ottawa scale. Results: The systematic search resulted in 776 articles, of which 7 studies were included in the analysis. In total, 88 patients (99 procedures) with an age ranging from 0 days to 8.1 years were included. Of these, 43 (49%) patients were neonates. The included cohort had esophageal atresia and tracheoesophageal fistula (n = 26), long-gap esophageal atresia (n = 5), congenital diaphragmatic hernia (n = 14), and congenital pulmonary airway malformations and other conditions needing lung resection (n = 43). Of the total 99 procedures, pathological desaturation was noticed in 13 (13.1%, 95% confidence interval 7.2-21.4) of them. Upon quality assessment, most of the studies were weaker in the selection and comparability domains. Conclusion: In this review, pathological cerebral desaturation was noticed in 13.1% of the pediatric thoracoscopic procedures. However, due to limited methodological quality of the included studies, further randomized multicentric studies comparing rcSO2 in open versus thoracoscopic surgeries are needed to derive definitive conclusions.

Perioperative Neuromonitoring in Children with Congenital Heart Disease

Although neonates and children with congenital heart disease are primarily hospitalized for cardiac and pulmonary diseases, they are also at an increased risk for neurologic injury due to both empiric differences that can exist in their nervous systems and acquired injury from cardiopulmonary pathology and interventions. Although early efforts in care focused on survival after reparative cardiac surgery, as surgical and anesthetic techniques have evolved and survival rates accordingly improved, the focus has now shifted to maximizing outcomes among survivors. Children and neonates with congenital heart disease experience seizures and poor neurodevelopmental outcomes at a higher rate than age-matched counterparts. The aim of neuromonitoring is to help clinicians identify patients at highest risk for these outcomes to implement strategies to mitigate these risks and to also help with neuroprognostication after an injury has occurred. The mainstays of neuromonitoring are (1) electroencephalographic monitoring to evaluate brain activity for abnormal patterns or changes and to identify seizures, (2) neuroimaging to reveal structural changes and evidence of physical injury in and around the brain, and (3) near-infrared spectroscopy to monitor brain tissue oxygenation and detect changes in perfusion. This review will detail the aforementioned techniques and their use in the care of pediatric patients with congenital heart disease.

Electroencephalography as a tool to predict cerebral oxygen metabolism during deep-hypothermic circulatory arrest in neonates with critical congenital heart disease

Objectives

Recent research suggests that increased cerebral oxygen use during surgical intervention for neonates with congenital heart disease may play a role in the development of postoperative white matter injury. The objective of this study is to determine whether increased cerebral electrical activity correlates with greater decrease of cerebral oxygen saturation during deep hypothermic circulatory arrest.

Methods

Neonates with critical congenital heart disease requiring surgical intervention during the first week of life were studied. All subjects had continuous neuromonitoring with electroencephalography and an optical probe (to quantify cerebral oxygen saturation) during cardiac surgical repair that involved the use of cardiopulmonary bypass and deep hypothermic circulatory arrest. A simple linear regression was used to investigate the association between electroencephalography metrics before the deep hypothermic circulatory arrest period and the change in cerebral oxygen saturation during the deep hypothermic circulatory arrest period.

Results

Sixteen neonates had both neuromonitoring modalities attached during surgical repair. Cerebral oxygen saturation data from 5 subjects were excluded due to poor data quality, yielding a total sample of 11 neonates. A simple linear regression model found that the presence of electroencephalography activity at the end of cooling is positively associated with the decrease in cerebral oxygen saturation that occurs during deep hypothermic circulatory arrest (P < .05).

Conclusions

Electroencephalography characteristics within 5 minutes before the initiation of deep hypothermic circulatory arrest may be useful in predicting the decrease in cerebral oxygen saturation that occurs during deep hypothermic circulatory arrest. Electroencephalography may be an important tool for guiding cooling and the initiation of circulatory arrest to potentially decrease the prevalence of new white matter injury in neonates with critical congenital heart disease.

Association between regional oxygen saturation and central venous saturation in pediatric patients undergoing cardiac surgery: A prospective observational study

BACKGROUND

We evaluated the correlation between regional oxygen saturation (rSO2 ) in the frontal and right renal dorsum (cerebral rSO2 and somatic rSO2 ) measured by near-infrared spectroscopy (INVOS™ 5100C, Medtronic) and central venous oxygen saturation (ScvO2 ) measured with a fiber-optic oximetry catheter (PediaSat™, Edwards Lifesciences) during surgery in order to determine whether noninvasive rSO2 could be used as an alternative to ScvO2 in pediatric cardiac surgery patients. We evaluated the correlation between regional tissue oxygen saturation (cerebral rSO2 and somatic rSO2 ) measured by near-infrared spectroscopy and other patient measures with central venous oxygen saturation (ScvO2 ) measured with a fiber-optic oximetry catheter to track global oxygen supply demand as a potential alternative or supplement to ScvO2 .

PATIENTS AND METHODS

This single-center prospective observational study enrolled 33 children (weight < 10 kg) who underwent cardiac surgery for congenital heart disease between February 2018 and November 2021. ScvO2 , cerebral rSO2 , and somatic rSO2 were recorded simultaneously after anesthesia induction and central venous catheter placement. Pearson's correlation coefficient and Bland-Altman analysis were used to determine the relationship between ScvO2 and rSO2 . We conducted correlation, Bland Altman, and multiple regression analyses to identify associations between rSO2 , patient measures, and ScvO2 values.

RESULTS

The patients' median age was 11.0 (quartile 2.0-16.0) months. Their weight was 7.2 (quartile 4.5-9.2) kg. Cerebral rSO2 was significantly positively correlated with ScvO2 (r2  = 0.29, p = .002 in all patients; r2  = 0.61, p = .013 in the patients without mixing at the atrial level), whereas somatic rSO2 was not. The Bland-Altman analysis demonstrated biases [95% confidence interval; 95% CI] (lower and upper limits of agreement [95% CI]) of 0.27% [-4.26 to 4.80] (-24.79 [-32.61 to -16.96] to 25.33 [17.50 to 33.16]) between cerebral rSO2 and ScvO2 and 0.91% [-5.48 to 7.30] (-34.43 [-45.47 to -23.39] to 36.25 [25.21 to 47.29]) between somatic rSO2 and ScvO2 . Preoperative brain natriuretic peptide (BNP) and SpO2 were independent variables associated with ScvO2 and cerebral and somatic rSO2 .

CONCLUSION

Cerebral rSO2 , SpO2 , and BNP were significantly correlated with ScvO2 , although the cerebral rSO2 correlation was greater for lesions without atrial mixing. rSO2 , BNP, and SpO2 might be used to track changes in ScvO2 but cerebral rSO2 is not sufficiently precise to replace it.

The Congenital Heart Surgeons' Society Presidents and Their Contributions

The Congenital Heart Surgeons' Society (CHSS) was founded by 16 congenital heart surgeons in 1973, who endeavored to share their clinical advances in an informal setting that would stimulate honest and forthright discussions. As the Society grew, prospective studies were organized from a centralized data center that was established and based first in Birmingham, Alabama, thence to Toronto, and recently in a collaboration between Toronto and the Cleveland Clinic. These studies formed the basis for a myriad of outcomes reports that favorably impacted surgical results. The Kirklin-Ashburn Fellowship was created and endowed by the membership which has been successful in training many congenital heart surgeons. The CHSS was then incorporated into a 501(c) (3) not-for-profit organization with bylaws, officers, and committees in 2002. Increased membership followed. The CHSS has become the face of congenital heart surgery in North America by affiliating with the World Journal for Pediatric and Congenital Heart Surgery, having one designated member on the American Board of Thoracic Surgery, and hosting joint meetings with the European Congenital Heart Surgeons Association. Since 2002, 11 presidents have been elected for two-year terms and have guided the advances that have been achieved by the CHSS. Their contributions and achievements are highlighted in chronological order.

Retroperitoneoscopic Surgery in Children Does Not Cause Pathological Desaturation in Cerebral/Renal Oxygenation on Near-Infrared Spectroscopy Compared with Laparoscopic and Thoracoscopic Surgery

Introduction: Cerebral and renal regional oxygen saturation (C-rSO₂ and R-rSO₂, respectively) were monitored using near-infrared spectroscopy in pediatric patients (range: 0.3-14.3 years) during minimally invasive surgery (MIS) taking at least 3 hours performed by laparoscopy (Lap), thoracoscopy (Tho), or retroperitoneoscopy (Ret) from January 2019 to December 2021. Materials and Methods: Criteria compared were operative time, preoperative/intraoperative hemoglobin, blood loss, mean arterial pressure, arterial partial pressure of carbon dioxide (PaCO₂), peripheral oxygen saturation (SpO₂), C-rSO₂, and R-rSO₂. Pathological desaturation (PD) was defined as >20% decrease from baseline, and statistical significance as P < .05. Results: Subjects (n = 79) were similar for gender, age, and body mass index. MIS procedures were: Lap = 45, Tho = 20, Ret = 14; one Lap case required conversion for severe adhesions, not PD. Intraoperative PaCO₂ (mmHg) was significantly higher in Tho (maximum: 59.5 ± 17.0, minimum: 39.9 ± 7.5) versus Lap (maximum: 39.9 ± 5.1, minimum: 34.6 ± 3.9) and Ret (maximum: 37.8 ± 4.2, minimum: 35.0 ± 3.3); P < .0001 (maximum), P = .0013 (minimum). Minimum intraoperative SpO₂ was significantly lower in Tho (P < .0001). Mean operative times were significantly shorter in Tho (259 ± 114 minutes) versus Lap (433 ± 154 minutes) and Ret (342 ± 100 minutes); P < .0001, respectively. PD was absent during Ret (C-rSO₂: 0/14 = 0% and R-rSO₂: 0/14 = 0%). Differences in PD for Lap (C-rSO₂: 7/45 = 15.6% and R-rSO₂: 10/45 = 22.2%) and Tho (C-rSO₂: 9/20 = 45.0%, and R-rSO₂: 7/20 = 35.0%) were significant; P = .0028 for C-rSO₂ and P = .0497 for R-rSO₂. Hemoglobin and blood loss were similar. Conclusions: PD was absent during Ret, despite longer operative times. If Ret is indicated for a procedure, neurodevelopmental sequelae of MIS could be minimized.

Optimizing Neurodevelopmental Outcomes in Neonates With Congenital Heart Disease

Neurodevelopmental impairment is a common and important long-term morbidity among infants with congenital heart disease (CHD). More than half of those with complex CHD will demonstrate some form of neurodevelopmental, neurocognitive, and/or psychosocial dysfunction requiring specialized care and impacting long-term quality of life. Preventing brain injury and treating long-term neurologic sequelae in this high-risk clinical population is imperative for improving neurodevelopmental and psychosocial outcomes. Thus, cardiac neurodevelopmental care is now at the forefront of clinical and research efforts. Initial research primarily focused on neurocritical care and operative strategies to mitigate brain injury. As the field has evolved, investigations have shifted to understanding the prenatal, genetic, and environmental contributions to impaired neurodevelopment. This article summarizes the recent literature detailing the brain abnormalities affecting neurodevelopment in children with CHD, the impact of genetics on neurodevelopmental outcomes, and the best practices for neonatal neurocritical care, focusing on developmental care and parental support as new areas of importance. A framework is also provided for the infrastructure and resources needed to support CHD families across the continuum of care settings.

Detection of hypoxia by near-infrared spectroscopy and pulse oximetry: a comparative study

SIGNIFICANCE

Pulse oximetry is widely used in clinical practice to monitor changes in arterial oxygen saturation (SpO2). However, decreases in SpO2 can be delayed relative to the actual clinical event, and near-infrared spectroscopy (NIRS) may detect alterations in oxygenation earlier than pulse oximetry, as shown in previous cerebral oxygenation monitoring studies.

AIM

We aim to compare the response of transcutaneous muscle NIRS measures of the tissue saturation index with pulse oximetry SpO2 during hypoxia.

APPROACH

Episodes of acute hypoxia were induced in nine anesthetized Yucatan miniature pigs. A standard pulse oximeter was attached to the ear of the animal, and a transcutaneous NIRS sensor was placed on the hind limb muscle. Hypoxia was induced by detaching the ventilator from the animal and reattaching it once the pulse oximeter reported 70% SpO2.

RESULTS

Twenty-four episodes of acute hypoxia were analyzed. Upon the start of hypoxia, the transcutaneous NIRS measures changed in 5.3 ± 0.4 s, whereas the pulse oximetry measures changed in 14.9 ± 1.0 s (p < 0.0001).

CONCLUSIONS

Transcutaneous muscle NIRS can detect the effects of hypoxia significantly sooner than pulse oximetry in the Yucatan miniature pig. A transcutaneous NIRS sensor may be used as an earlier detector of oxygen saturation changes in the clinical setting than the standard pulse oximeter.

ASNM and ASN joint guidelines for transcranial Doppler ultrasonic monitoring: An update

Today, it seems prudent to reconsider how ultrasound technology can be used for providing intraoperative neurophysiologic monitoring that will result in better patient outcomes and decreased length and cost of hospitalization. An extensive and rapidly growing literature suggests that the essential hemodynamic information provided by transcranial Doppler (TCD) ultrasonography neuromonitoring (TCDNM) would provide effective monitoring modality for improving outcomes after different types of vascular, neurosurgical, orthopedic, cardiovascular, and cardiothoracic surgeries and some endovascular interventional or diagnostic procedures, like cardiac catheterization or cerebral angiography. Understanding, avoiding, and preventing peri- or postoperative complications, including neurological deficits following abovementioned surgeries, endovascular intervention, or diagnostic procedures, represents an area of great public and economic benefit for society, especially considering the aging population. The American Society of Neurophysiologic Monitoring and American Society of Neuroimaging Guidelines Committees formed a joint task force and developed updated guidelines to assist in the use of TCDNM in the surgical and intensive care settings. Specifically, these guidelines define (1) the objectives of TCD monitoring; (2) the responsibilities and behaviors of the neurosonographer during monitoring; (3) instrumentation and acquisition parameters; (4) safety considerations; (5) contemporary rationale for TCDNM; (6) TCDNM perspectives; and (7) major recommendations.

Significant neonatal intraoperative cerebral and renal oxygen desaturation identified with near-infrared spectroscopy

INTRODUCTION

Near-infrared spectroscopy (NIRS) was used to monitor intraoperative regional oxygen saturation (rSO₂) during open (Op) and minimally invasive (MI) surgery performed in neonates (N) and children.

MATERIALS AND METHODS

NIRS sensors were applied to the forehead and flanks for cerebral rSO₂ (C-rSO₂) and renal rSO₂ (R-rSO₂), respectively. MI included laparoscopy (La), retroperitoneoscopy (Re) and thoracoscopy (Th). In children, Op and MI were major operations taking at least 3 h (MOp; MMI). Pathological desaturation (PD) was defined as > 20% deterioration in rSO₂.

RESULTS

Mean ages at surgery were N: 5.2 ± 8.2 days, MOp: 2.4 ± 2.9 years, and MMI: 3.8 ± 4.3 years. Despite significantly shorter operative times in N (169 ± 94 min; p < 0.0001), PD was significantly worse; PD(C-rSO₂): N = 14/35 (40.0%) versus MOp = 3/36 (8.3%) and MMI = 7/58 (12.1%); p = 0.0006, and PD(R-rSO₂): N = 27/35 (77.1%) versus MOp = 6/36 (16.7%) and MMI = 7/58 (12.1%); p < 0.0001, respectively. PD(R-rSO₂) occurred immediately with visceral reduction in NOp (Fig. 1) and PD was frequent during NMI(Th) (Fig. 2). rSO₂ was stable throughout MOp and MMI (Fig. 3). Fig. 1 Pathological desaturation in renal rSO₂ after visceral reduction for gastroschisis. Renal rSO₂ deteriorated immediately after viscera were returned to the abdominal cavity rSO₂ regional oxygen saturation Fig. 2 Fragility of tissue perfusion during thoracoscopic lung lobectomy in a neonate. Pathological desaturation occurred frequently during neonatal thoracoscopic surgery rSO₂ regional oxygen saturation Fig. 3 Changes in cerebral and renal rSO₂ according to operative time. Cerebral and renal rSO₂ did not appear to change according to operative time during major open and major minimally invasive surgery in children. rSO₂ regional oxygen saturation CONCLUSIONS: NIRS is a non-invasive technique for monitoring rSO₂ as an indicator of intraoperative stress and vascular perfusion. PD was so significant in neonates that intraoperative NIRS is highly recommended during thoracoscopy and procedures requiring visceral manipulation.

The use of cerebral oximetry in cardiac surgery: A systematic review and meta-analysis of randomized controlled trials

High prevalence of cerebral desaturation is associated with postoperative neurological complications in cardiac surgery. However, the evidence use of cerebral oximetry by correcting cerebral desaturation in the reduction of postoperative complications remains uncertain in the literature. This systematic review and meta-analysis aimed to examine the effect of cerebral oximetry on the incidence of postoperative cognitive dysfunction in cardiac surgery. Databases of MEDLINE, EMBASE, and CENTRAL were searched from their inception until April 2021. All randomized controlled trials comparing cerebral oximetry and blinded/no cerebral oximetry in adult patients undergoing cardiac surgery were included. Observational studies, case series, and case reports were excluded. A total of 14 trials (n = 2,033) were included in this review. Our pooled data demonstrated that patients with cerebral oximetry were associated with a lower incidence of postoperative cognitive dysfunction than the control group (studies = 4, n = 609, odds ratio [OR]: 0.15, 95% confidence interval [CI]: 0.04 to 0.54, P = 0.003, I² = 88%; certainty of evidence = very low). In terms of postoperative delirium (OR: 0.75, 95%CI: 0.50-1.14, P = 0.18, I² = 0%; certainty of evidence = low) and postoperative stroke (OR: 0.81 95%CI: 0.37-1.80, P = 0.61, I² = 0%; certainty of evidence = high), no significant differences (P > 0.05) were reported between the cerebral oximetry and control groups. In this meta-analysis, the use of cerebral oximetry monitoring in cardiac surgery demonstrated a lower incidence of postoperative cognitive dysfunction. However, this finding must be interpreted with caution due to the low level of evidence, high degree of heterogeneity, lack of standardized cognitive assessments, and cerebral desaturation interventions.

Near-Infrared Spectroscopy Monitoring in Pediatric Anesthesiology: A Pro-Con Discussion

Near-infrared spectroscopy (NIRS) has been increasingly used as a non-invasive measurement of cerebral tissue oxygen saturation. The aim of this short review is to discuss the benefits and drawbacks of its use in the pediatric anesthesia population. In the context of cardiac surgery, lower intraoperative NIRS values have shown a modest association with neurodevelopmental outcomes while lower neonatal intensive care unit NIRS values have been correlated with reduced neurodevelopment in children. However, it is still unclear if management aimed at increasing cerebral tissue oxygenation would have any benefit on these outcomes. Without prospective research looking into the effects of intervention given proper thresholds, the true benefit of NIRS use is still up for debate. Even with current research gaps, its use in the clinical setting continues.

Deep Hypothermic Circulatory Arrest in the Pediatric Population Undergoing Cardiac Surgery With Electroencephalography Monitoring: A Systematic Review and Meta-Analysis

OBJECTIVE

Cardiac surgery for repair of congenital heart defects poses unique hazards to the developing brain. Deep hypothermic circulatory arrest (DHCA) is a simple and effective method for facilitating a bloodless surgical field during congenital heart defect repair. There are, however, some concerns that prolonged DHCA increases the risk of nervous system injury. The electroencephalogram (EEG) is used in adult and, to a lesser extent, pediatric cardiac procedures as a neuromonitoring method. The present study was performed to assess outcomes following DHCA with EEG monitoring in the pediatric population.

DESIGN

In this systematic review and meta-analysis, the PubMed, Cochrane Central Register of Controlled Trials, Scopus, Institute of Science Index, and Embase databases were searched from inception for relevant articles. A fixed- or random-effects model, as appropriate, was used.

SETTING

Surgical setting.

PARTICIPANTS

Pediatric population (≤18 y old).

INTERVENTIONS

DHCA (18°C) with EEG monitoring.

MEASUREMENTS AND MAIN RESULTS

Nineteen articles with 1,267 pediatric patients ≤18 years were included. The event rate of clinical and EEG seizures among patients who underwent DHCA was 12.9% and 14.9%, respectively. Mortality was found to have a 6.3% prevalence. A longer duration of DHCA was associated with a higher risk of EEG seizure and neurologic abnormalities. In addition, seizures were associated with increased neurologic abnormalities and neurodevelopmental delay.

CONCLUSIONS

EEG and neurologic abnormalities were common after DHCA. A longer duration of DHCA was found to lead to more EEG seizure and neurologic abnormalities. Moreover, EEG seizures were more common than clinical seizures. Seizures were found to be associated with increased neurologic abnormalities and neurodevelopmental delay.

A wireless, skin-interfaced biosensor for cerebral hemodynamic monitoring in pediatric care

The standard of clinical care in many pediatric and neonatal neurocritical care units involves continuous monitoring of cerebral hemodynamics using hard-wired devices that physically adhere to the skin and connect to base stations that commonly mount on an adjacent wall or stand. Risks of iatrogenic skin injuries associated with adhesives that bond such systems to the skin and entanglements of the patients and/or the healthcare professionals with the wires can impede clinical procedures and natural movements that are critical to the care, development, and recovery of pediatric patients. This paper presents a wireless, miniaturized, and mechanically soft, flexible device that supports measurements quantitatively comparable to existing clinical standards. The system features a multiphotodiode array and pair of light-emitting diodes for simultaneous monitoring of systemic and cerebral hemodynamics, with ability to measure cerebral oxygenation, heart rate, peripheral oxygenation, and potentially cerebral pulse pressure and vascular tone, through the utilization of multiwavelength reflectance-mode photoplethysmography and functional near-infrared spectroscopy. Monte Carlo optical simulations define the tissue-probing depths for source-detector distances and operating wavelengths of these systems using magnetic resonance images of the head of a representative pediatric patient to define the relevant geometries. Clinical studies on pediatric subjects with and without congenital central hypoventilation syndrome validate the feasibility for using this system in operating hospitals and define its advantages relative to established technologies. This platform has the potential to substantially enhance the quality of pediatric care across a wide range of conditions and use scenarios, not only in advanced hospital settings but also in clinics of lower- and middle-income countries.

Sensitivity of a Next-Generation NIRS Device to Detect Low Mixed Venous Oxyhemoglobin Saturations in the Single Ventricle Population

Regional cerebral oxygenation index (rSO2) based on near-infrared spectroscopy (NIRS) is frequently used to detect low venous oxyhemoglobin saturation (ScvO2). We compared the performance of 2 generations of NIRS devices. Clinically obtained, time-matched cerebral rSO2 and ScvO2 values were compared in infants monitored with the FORE-SIGHT (n = 73) or FORE-SIGHT ELITE (n = 47) by linear regression and Bland-Altman analyses. In both devices, cerebral rSO2 correlated poorly with measured ScvO2 (FORE-SIGHT partial correlation 0.50 [95% confidence interval {CI}, 0.40-0.58]; FORE-SIGHT ELITE partial correlation 0.47 [0.39-0.55]) and mean bias was +8 (standard deviation [SD] 13.2) for FORE-SIGHT and +14 (SD 12.5) for FORE-SIGHT ELITE. When ScvO2 was <30%, rSO2 was <40 in 8% of FORE-SIGHT ELITE readings. Future NIRS should be validated in more hypoxic cohorts.

Direct postoperative protein S100B and NIRS monitoring in infants after pediatric cardiac surgery enrich early mortality assessment at the PICU

BACKGROUND

Neuromonitoring using plasmatic biomarkers such as S100B and near-infrared spectroscopy (NIRS) represents a standard procedure for detecting cerebral damage after cardiac surgery. Their use in pediatric clinical assessment, however, is negligible.

OBJECTIVES

The goal of this study was to evaluate the predictive role of S100B levels and cerebral oxygenation in postoperative pediatric cardiac patients for survival and potential cerebral injuries.

METHODS

A retrospective cohort study of infants after cardiac surgery. Primary outcome was survival until discharge. Intra/postoperative vital signs and laboratory data were measured and statistically analyzed.

RESULTS

Seven out of 226 infants were non-survivors. Non-survivors had significantly lower cerebral saturation than survivors, as well as elevated S100B values at admission, associated with lower arterial pressure and higher serum lactate levels.

CONCLUSION

Although significant differences of S100B and crO₂ values between survivors and non-survivors were found, no critical thresholds could be established from the data. Nevertheless, changes from the norm in these parameters should raise awareness for critical clinical development.

Investigation of the Relationship between Cerebral Near-Infrared Spectroscopy Measurements and Cerebrovascular Event in Coronary Artery Bypass Grafting Operation in Patients without Carotid Stenosis and Patients with Carotid Stenosis below Surgical Margins

OBJECTIVES

Stroke is an important cause of mortality and morbidity in surgery. In the present study, we examined the cerebral oximetry values of patients with carotid artery stenosis who did not present surgical indications and those who did not present carotid artery stenosis in coronary artery bypass grafting (CABG) surgery by comparing their cerebral oximetry values with cerebrovascular disease (CVD).

METHODS

Between January and May 2014, 40 patients who underwent isolated CABG were included in the study. Cerebral oximetry probes were placed prior to induction of anesthesia. Cerebral oximetry values were recorded before induction, in the pump (cardiopulmonary bypass) inlet period, in the post-clamp period, in the pump outlet period, and in the intensive care unit and neurological complications.

RESULTS

There was no difference between the groups in terms of demographic data and routine follow-up parameters. Intraoperative surgical data and early postoperative results were similar in both groups. When comparing the groups, there were no statistically significant results in cerebral oximetry values and CVD development. Only one patient in group 2 had postoperative CVD and this patient was discharged from the hospital with right hemiplegia. Mean arterial pressure (MAP)levels were significantly higher in Group 2 (P<0.05).

CONCLUSION

The follow-up of cerebral perfusion with a method like near-infrared spectroscopy (NIRS) will ensure that MAP is adjusted with interventions that will be made according to changes in NIRS. Thus, it will be possible to avoid unnecessary medication and flow-rate increase with cerebral oxygen saturation (rSO2) follow-up.

Most High-Intensity Transient Signals Are Not Associated With Specific Surgical Maneuvers

Background:

Mortality after congenital heart defect surgery has dropped dramatically in the last few decades. Current research on long-term outcomes has focused on preventing secondary neurological sequelae, for which embolic burden is suspected. In children, little is known of the correlation between specific surgical maneuvers and embolic burden. Transcranial Doppler ultrasound is highly useful for detecting emboli but has not been widely used with infants and children.

Methods:

Bilateral middle cerebral artery blood flow was continuously monitored from sternal incision to chest closure in 20 infants undergoing congenital heart defect repair or palliative surgery. Embolus counts for specific maneuvers were recorded using widely accepted criteria for identifying emboli via high-intensity transient signals (HITS).

Results:

An average of only 13% of all HITS detected during an operation were correlated with any of the surgical maneuvers of interest. The highest mean number of HITS associated with a specific maneuver occurred during cross-clamp removal. Cross-clamp placement also had elevated HITS counts that significantly differed from other maneuvers.

Conclusions:

In this study of infants undergoing cardiac surgery with cardiopulmonary bypass, the great majority of HITS detected are not definitively associated with a specific subset of surgical maneuvers. Among the measured maneuvers, removal of the aortic cross-clamp was associated with the greatest occurrence of HITS. Future recommended research efforts include identifying and confirming other sources for emboli and longitudinal outcome studies to determine if limiting embolic burden affects long-term neurological outcomes.

Haemodynamic effects of premedication for neonatal intubation: an observational study

OBJECTIVE

To examine changes in blood pressure (BP), cardiac output (CO) and cerebral regional oxygen saturation (rScO2) with administration of premedication for neonatal intubation.

DESIGN

Pilot, prospective, observational study. Oxygen saturation, heart rate, CO, rScO2 and BP data were collected. Monitoring began 5 min prior to premedication and continued until spontaneous movement.

SETTING

Single-centre, level 3 neonatal intensive care unit PATIENTS: 35 infants, all gestational ages. 81 eligible infants: 66 consented, 15 refused.

INTERVENTIONS

Intravenous atropine, fentanyl or morphine, ±cisatracurium MAIN OUTCOME MEASURES: BP, CO, rScO2 RESULTS: n=37 intubations. Mean gestational age and median birth weight were 31 4/7 weeks and 1511 g. After premedication, 10 episodes resulted in a BP increase from baseline and 27 in a BP decrease. Of those whose BP decreased, 17 had <20% decrease and 10 had ≥20% decrease. Those with <20% BP decrease took an average of 2.5 min to return to baseline while those with a ≥20% BP decline took an average of 15.2 min. Three did not return to baseline by 35 min. Following intubation, further declines in BP (21%-51%) were observed in eight additional cases. One infant required a bolus for persistently low BPs. CO and rScO2 changes were statistically similar between the two groups.

CONCLUSION

About 30% of infants dropped their BP by ≥20% after premedication for elective intubation. These BP changes were not associated with any significant change in rScO2 or CO. More data are needed to better characterise the immediate haemodynamic changes and clinical outcomes associated with premedication.

The Organ-Protective Effect of Higher Partial Pressure of Arterial Carbon Dioxide in the Normal Range for Infant Patients Undergoing Ventricular Septal Defect Repair

Hypercapnia has been reported to play an active role in protection against organ injury. The aim of this study was to determine whether a higher level of partial pressure of arterial carbon dioxide (PaCO₂) within the normal range in pediatric patients undergoing cardiac surgery had a similar organ-protective effect. From May 2017 to May 2018, 83 consecutive infant patients undergoing ventricular septal defect (VSD) repair with cardiopulmonary bypass were retrospectively enrolled. We recorded the end-expiratory tidal partial pressure of carbon dioxide (Pet-CO₂) as an indirect and continuous way to reflect the PaCO₂. The patients were divided into a low PaCO₂ group (LPG; 30 mmHg < Pet-CO₂ < 40 mmHg) and a high PaCO₂ group (HPG; 40 mmHg < Pet-CO₂ < 50 mmHg). The regional cerebral oxygen saturation (rScO₂), cerebral blood flow velocity (CBFV), and hemodynamics at five time points throughout the operation, and perioperative data were recorded and analyzed for the two groups. In total, 34 LPG and 49 HPG patients were included. Demographics and perioperative clinical data showed no significant difference between the groups. Compared with LPG, the HPG produced lower postoperative creatine kinase isoenzyme-MB (40.88 versus 50.34 ng/mL, P = 0.038). The postoperative C-reactive protein of HPG trended lower than in LPG (61.09 versus 73.4 mg/L, P = 0.056). The rScO₂ and mean CBFV of HPG were significantly higher compared with LPG (P < 0.05) except at the end of cardiopulmonary bypass. Hemodynamic data showed no significant difference between the groups. As a convenient and safe approach, higher-normal PaCO₂ could attenuate brain injury, heart injury, and inflammatory response in infant patients undergoing VSD repair.

Near-infrared spectroscopy: An important tool during the blalock-taussig shunt

Near infra red spectroscopy (NIRS) is a noninvasive diagnostic tool for measuring regional oxygen saturation (rSO2). Cerebral oxygenation measured with NIRS is used to corroborate mixed venous oxygenation and hence considered an indicator of tissue perfusion. We describe NIRS guiding an anatomical variation leading to inadequate cerebral circulation or any impairment in cerebral oxygen delivery during Blalock Taussig shunt.

Non-invasive optical neuromonitoring of the temperature-dependence of cerebral oxygen metabolism during deep hypothermic cardiopulmonary bypass in neonatal swine

Management of deep hypothermic (DH) cardiopulmonary bypass (CPB), a critical neuroprotective strategy, currently relies on non-invasive temperature to guide cerebral metabolic suppression during complex cardiac surgery in neonates. Considerable inter-subject variability in temperature response and residual metabolism may contribute to the persisting risk for postoperative neurological injury. To characterize and mitigate this variability, we assess the sufficiency of conventional nasopharyngeal temperature (NPT) guidance, and in the process, validate combined non-invasive frequency-domain diffuse optical spectroscopy (FD-DOS) and diffuse correlation spectroscopy (DCS) for direct measurement of cerebral metabolic rate of oxygen (CMRO₂). During CPB, n = 8 neonatal swine underwent cooling from normothermia to 18℃, sustained DH perfusion for 40 min, and then rewarming to simulate cardiac surgery. Continuous non-invasive and invasive measurements of intracranial temperature (ICT) and CMRO₂ were acquired. Significant hysteresis (p < 0.001) between cooling and rewarming periods in the NPT versus ICT and NPT versus CMRO₂ relationships were found. Resolution of this hysteresis in the ICT versus CMRO₂ relationship identified a crucial insufficiency of conventional NPT guidance. Non-invasive CMRO₂ temperature coefficients with respect to NPT (Q₁₀ = 2.0) and ICT (Q₁₀ = 2.5) are consistent with previous reports and provide further validation of FD-DOS/DCS CMRO₂ monitoring during DH CPB to optimize management.

Combined Multimodal Cerebral Monitoring and Focused Hemodynamic Assessment in the First 72 h in Extremely Low Gestational Age Infants

BACKGROUND

Characteristic changes in cerebral saturation (CrSO2), amplitude-integrated electroencephalography (aEEG), and echocardiography (ECHO) may be associated with intraventricular hemorrhage (IVH); however, the feasibility of their combined application is not known.

OBJECTIVE

The aim of this work was to investigate the feasibility and safety of combined multimodal cerebral and hemodynamic monitoring in extremely low gestational age (ELGA) infants in the first 72 h after birth.

METHODS

In this prospective -observational study of 50 infants born between 23 + 0 and 27 + 6 weeks gestation, we measured CrSO2 and aEEG, starting <8 h until 72 h of age. Sequential echocardiography and head ultrasound were performed at 4-8, 12-18, 24-30, and 48-60 h of age. The primary outcome was feasibility of multimodal monitoring, defined as >75% of the subjects satisfying at least 3/4 criteria: (a) CrSO2 and (b) aEEG monitoring each for >75% of the time, and (c) at least 2 out of 4 ECHO and (d) head ultrasounds (at least one by age 24 h). Adverse reactions to sensors, desaturation, and bradycardia during ultrasound studies were recorded.

RESULTS

Fifty infants were enrolled over 14 months. Multimodal monitoring was feasible in 49 (98%) infants. Forty-one (82%) infants fulfilled all 4 criteria. Mild erythema below CrSO2 sensors lasting 3-8 h without skin breakdown was noted in 8/50 subjects (16%). Desaturation was noted during 17/197 (8.6%) of the ultrasound studies. In total, 26/50 (52%) infants developed IVH (grade I/II, n = 22; grade III/IV, n = 4).

CONCLUSION

Multimodal monitoring is feasible, safe, and well tolerated in ELGA infants in the first 72 h after birth.

Cerebral regional oxygen saturation: a useful monitor during a surgical procedure involving the right-sided aortic arch in an infant

A right aortic arch with an aberrant left subclavian artery and a Kommerell's diverticulum represents a rare anatomic variant carrying the risk of dissection or rupture. Resection of the diverticulum and re-implantation of the left subclavian artery during childhood have been recommended. Because of the risk of cerebral blood flow reduction during the aberrant subclavian artery re-implantation to the common carotid artery, monitoring and prompt measures to curb blood flow reduction are required. A 5-month-old boy was scheduled to undergo resection surgery. During the translocation of the aberrant subclavian artery to the common carotid artery, his regional oxygen saturation (rSO₂) in the left cerebrum began to decrease. We increased the end-tidal CO₂ (EtCO₂), mean arterial pressure, and a fraction of inspired oxygen, successfully restoring the rSO₂ to the initial level. No postoperative neurological complications were observed. Our experience with this patient suggests that rSO₂ monitoring is a useful, and intervention protocol including hypercapnia, elevated mean arterial pressure, and hyperoxia to counter the decreased cerebral blood flow is effective in infant patients undergoing right-sided aortic arch surgery.

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.

Changes in cerebral oxygenation based on intraoperative ventilation strategy

Introduction

Cerebral oxygenation can be monitored clinically by cerebral oximetry (regional oxygen saturation, rSO₂) using near-infrared spectroscopy (NIRS). Changes in rSO₂ have been shown to precede changes in pulse oximetry, providing an early detection of clinical deterioration. Cerebral oximetry values may be affected by various factors, including changes in ventilation. The aim of this study was to evaluate the changes in rSO₂ during intraoperative changes in mechanical ventilation.

Patients and methods

Following the approval of the institutional review board (IRB), tissue and cerebral oxygenation were monitored intraoperatively using NIRS. Prior to anesthetic induction, the NIRS monitor was placed on the forehead and over the deltoid muscle to obtain baseline values. NIRS measurements were recorded each minute over a 5-min period during general anesthesia at four phases of ventilation: 1) normocarbia (35–40 mmHg) with a low fraction of inspired oxygen (FiO₂) of 0.3; 2) hypocarbia (25–30 mmHg) and low FiO₂ of 0.3; 3) hypocarbia and a high FiO₂ of 0.6; and 4) normocarbia and a high FiO₂. NIRS measurements during each phase were compared with sequential phases using paired t-tests.

Results

The study cohort included 30 adolescents. Baseline cerebral and tissue oxygenation were 81% ± 9% and 87% ± 5%, respectively. During phase 1, cerebral rSO₂ was 83% ± 8%, which decreased to 79% ± 8% in phase 2 (hypocarbia and low FiO₂). Cerebral oxygenation partially recovered during phase 3 (81% ± 9%) with the increase in FiO₂ and then returned to baseline during phase 4 (83% ± 8%). Each sequential change (e.g., phase 1 to phase 2) in cerebral oxygenation was statistically significant (p < 0.01). Tissue oxygenation remained at 87%–88% throughout the study.

Conclusion

Cerebral oxygenation declined slightly during general anesthesia with the transition from normocarbia to hypocarbic conditions. The rSO₂ decrease related to hypocarbia was easily reversed with a return to baseline values by the administration of supplemental oxygen (60% vs. 30%).

Data on the effect of target temperature management at 32-34 °C in cardiac arrest patients considering assessment by regional cerebral oxygen saturation: A multicenter retrospective cohort study

This data article contains raw data and supplementary analyzed data regarding to the article entitled “Effect of target temperature management at 32–34 °C in cardiac arrest patients considering assessment by regional cerebral oxygen saturation: A multicenter retrospective cohort study”. We examined the effectiveness of target temperature management (TTM) at 32–34 °C considering degrees of patients’ cerebral injury and cerebral circulation assessed by regional cerebral oxygen saturation (rSO₂). The research is a secondary analysis of prospectively collected registry, in which comatose patients who were transferred to 15 hospitals in Japan after out-of-hospital cardiac arrest (OHCA), and we included 431 study patients. Propensity score analysis revealed that TTM at 32–34 °C decreased all-cause mortality in patients with rSO₂ 41–60%, and increased favorable neurological outcomes in patients with rSO₂ 41–60% in the original research article. With regard to the balance of covariates of propensity-score matching (PSM) and inverse-probability weighting (IPW) analyses, some covariates were not well balanced after the analyses between groups. The overlap plots indicate the overlap of densities of the propensity scores are low in group rSO₂ 41–60% and group rSO₂ ≥ 61%. When patients were limited to those who achieved return of spontaneous circulation (ROSC) until/on hospitals arrival, TTM still tended to decrease all-cause mortality and increase favorable outcomes in group rSO₂ 41–60%.

Neuroprotective Anesthesia Regimen and Intensive Management for Pediatric Cardiac Surgery with Cardiopulmonary Bypass: a Review and Initial Experience

This article describes our proposal for routine anesthesia, intraoperative medical management, cerebral and physiological monitoring during pediatric cardiac surgery with cardiopulmonary bypass that intend to provide appropriate anesthesia (analgesia, hypnosis), neuroprotection, adequate cerebral and systemic oxygen supply, and preventing against drugs neurotoxicity. A concise retrospective data is presented.

Cerebral Oximetry for Cardiac and Vascular Surgery

The technology of transcranial near-infrared spectroscopy (NIRS) for the measurement of cerebral oxygen balance was introduced 25 years ago. Until very recently, there has been only occasional interest in its use during surgical monitoring. Now, however, substantial technologic advances and numerous clinical studies have, at least partly, succeeded in overcoming long-standing and widespread misunderstanding and skepticism regarding its value. Our goals are to clarify common misconceptions about near-infrared spectroscopy and acquaint the reader with the substantial literature that now supports cerebral oximetric monitoring in cardiac and major vascular surgery.

The role of EEG recordings in children undergoing cardiac surgery for congenital heart disease

BACKGROUND

Neurological dysfunction may occur after corrective cardiac surgery using cardio-pulmonary bypass (CPB) with or without circulatory arrest. Different neurophysiological monitoring systems have been employed to detect neurological complications and possible brain injury in infants and children during and after cardiac surgery. The value of Elecetroencephalogram (EEG) in infants and children at risk for neurological sequelae has not been systematically studied.

METHODS

Sequential performance of two EEGs before and after cardiac surgery at a tertiary University Hospital to screen for possible brain injury after cardiac surgery in neonates and children undergoing CPB surgery. In addition, a complete neurological examination and assessment by a physiotherapist was performed.

RESULTS

Over a 4-year period, in 313 patients (age: 54.2 ± 55.7 months; normal initial EEG) after cardiac surgery CPB (duration of surgery: 146.0 ± 58.9 min; aortic cross clamp time: 34.1 ± 19.1 min), a 19-channel EEG recording was performed 2.4 ± 1.8 days prior to and 11.6 ± 5.3 days after cardiac surgery. An abnormal EEG was detected in only 8 of 313 patients (2.5%; focal slowing: 1, generalised slowing: 5, epiletiform discharges: 2) after cardiac surgery, while the EEG was normal in the remaining 305 patients (97.5%). In 1 patient, an intra-cerebral pathology was seen on MRI (ischemic); in 5 patients, follow-up EEGs were performed, which revealed normalized findings. None of the 8 patients demonstrated new focal neurological deficits on physical examination, but 33 (9.7%) children demonstrated minor abnormalities (e.g., subtle motor asymmetry, increase in muscle tone, etc.), which were unrelated to abnormal EEG findings.

CONCLUSIONS

According to the used protocol, pathological EEG findings were very infrequent in our study cohort. The routine and indiscriminative recording of EEGs in children before and after corrective or palliative cardiac surgery for congenital heart disease using CPB is not recommended. Further intra-operative neuromonitoring methods with immediate intervention should be evaluated.

Prognostic value of cerebral tissue oxygen saturation during neonatal extracorporeal membrane oxygenation

Objectives

Extracorporeal membrane oxygenation support is indicated in severe and refractory respiratory or circulatory failures. Neurological complications are typically represented by acute ischemic or hemorrhagic lesions, which induce higher morbidity and mortality. The primary goal of this study was to assess the prognostic value of cerebral tissue oxygen saturation (StcO₂) on mortality in neonates and young infants treated with ECMO. A secondary objective was to evaluate the association between StcO₂ and the occurrence of cerebral lesions.

Study design

This was a prospective study in infants < 3 months of age admitted to a pediatric intensive care unit and requiring ECMO support.

Measurements

The assessment of cerebral perfusion was made by continuous StcO₂ monitoring using near-infrared spectroscopy (NIRS) sensors placed on the two temporo-parietal regions. Neurological lesions were identified by MRI or transfontanellar echography.

Results

Thirty-four infants <3 months of age were included in the study over a period of 18 months. The ECMO duration was 10±7 days. The survival rate was 50% (17/34 patients), and the proportion of brain injuries was 20% (7/34 patients). The mean StcO₂ during ECMO in the non-survivors was reduced in both hemispheres (p = 0.0008 right, p = 0.03 left) compared to the survivors. StcO₂ was also reduced in deceased or brain-injured patients compared to the survivors without brain injury (p = 0.002).

Conclusion

StcO₂ appears to be a strong prognostic factor of survival and of the presence of cerebral lesions in young infants during ECMO.

Brain Monitoring and Protection During Pediatric Cardiac Surgery

With advances in medical care, survival after cardiac surgery for congenital heart disease has dramatically improved, and attention is increasingly focused on longterm functional morbidities, especially neurodevelopmental outcomes, with their profound consequences to patients and society. There are multiple reasons for concern about brain injury. Some cardiac defects are associated with brain anomalies and altered cerebral blood flow regulation. Brain imaging studies have demonstrated that injury to gray and white matter is quite frequent before heart surgery in neonates. Cardiopulmonary bypass and deep hypothermic circulatory arrest are associated with shortand longer-term adverse neurologic outcome. Additional brain injury can occur during the patient's recovery from surgery. Strategies to optimize neurologic outcome continue to evolve. With new technological developments, perioperative neurologic monitoring of small children has become easier, and data suggest these modalities usefully identify adverse neurologic events and might predict outcome. Monitoring methods to be discussed include processed electroencephalography, near infrared spectroscopy, and transcranial Doppler ultrasound. Alternative perfusion techniques to deep hypothermic circulatory arrest have been developed, such as regional antegrade cerebral perfusion during cardiopulmonary bypass. Other neuroprotective strategies employed during open-heart surgery include temperature regulation, acid-base management, degree of hemodilution, blood glucose control and anti-inflammatory therapies. Evidence of the impact of these measures on neurologic outcome is examined, and deficiencies in our current understanding of neurologic function in children with congenital heart disease are identified.

Human Auditory Evoked Potentials in the Assessment of Brain Function During Major Cardiovascular Surgery

Focal neurologic and intellectual deficits or memory problems are relatively frequent after cardiac surgery. These complications have been associated with cerebral hypoperfusion, embolization, and inflammation that occur during or after surgery. Auditory evoked potentials, a neurophysiologic technique that evaluates the function of neural structures from the auditory nerve to the cortex, provide useful information about the functional status of the brain during major cardiovascular procedures. Skepticism regarding the presence of artifacts or difficulty in their interpretation has outweighed considerations of its potential utility and noninvasiveness. This paper reviews the evidence of their potential applications in several aspects of the management of cardiac surgery patients. The sensitivity of auditory evoked potentials to the effects of changes in brain temperature makes them useful for monitoring cerebral hypothermia and rewarming during cardiopulmonary bypass. The close relationship between evoked potential waveforms and specific anatomic structures facilitates the assessment of the functional integrity of the central nervous system in cardiac surgery patients. This feature may also be relevant in the management of critical patients under sedation and coma or in the evaluation of their prognosis during critical care. Their objectivity, reproducibility, and relative insensitivity to learning effects make auditory evoked potentials attractive for the cognitive assessment of cardiac surgery patients. From a clinical perspective, auditory evoked potentials represent an additional window for the study of underlying cerebral processes in healthy and diseased patients. From a research standpoint, this technology offers opportunities for a better understanding of the particular cerebral deficits associated with patients who are undergoing major cardiovascular procedures.