Intraoperative Cerebral Oximetry Research Articles

Effect of combined use of cerebral oximetry and electroencephalogram monitoring on the incidence of perioperative neurocognitive disorders in adult cardiac and non-cardiac surgery: A systematic review of randomized and non-randomized trials

Background: There is insufficient evidence to recommend using either intraoperative cerebral oximetry or (processed) electroencephalogram (EEG) alone for preventing perioperative neurocognitive disorders (PNDs). Objective: To evaluate the effectiveness of combined use of cerebral oximetry and electroencephalogram-guided anesthesia on the incidence of PNDs in adult patients undergoing cardiac and non-cardiac interventions. Methods: A PICOS - based systematic review of English articles using Pubmed and Embase (from inception to August 2022) was performed. There were no exclusion criteria regarding the type of the study. Abstract proceedings and new study protocols or ongoing studies were not included. Review articles were analyzed in search of eligible references. All possible terms that were illustrative of PNDs were used. Results: Among the 63 full manuscripts that were analyzed in detail, 15 met the inclusion criteria. We found 2 retrospective, 8 prospective observational and 5 randomized controlled trials of which 1 did not evaluate the use of neuromonitoring in the randomization process. The definition and the methods used to diagnose PNDs were very heterogeneous. Only 8 studies used an algorithm to avoid/treat cerebral oxygen desaturation and/or to treat EEG abnormalities. Overall, there was a tendency towards less PNDs in studies where such an algorithm was used. Conclusions: Our results suggest that integrating information obtained from cerebral oximetry and an EEG monitor may reduce the incidence of PNDs whenever an adapted algorithm is used to improve brain function.

Utility of sample entropy from intraoperative cerebral NIRS oximetry data in the diagnosis of postoperative cognitive improvement.

Background: Appropriate monitoring and early recognition of postoperative cognitive improvement (POCI) are essential. Near-infrared spectroscopy (NIRS) showed the predictive potential of POCI. Non-linear dynamical analysis is a powerful approach for understanding intraoperative regional cerebral oxygen saturation (rSO2). Objective: We hypothesized that the sample entropy (SampEn) value of intraoperative rSO2 has the potential to predict POCI. Methods: This retrospective cohort study was conducted from June 2019 and December 2020 in a tertiary hospital in Beijing, China. A total of 126 consecutive patients who underwent carotid endarterectomy (CEA) were screened. 57 patients were included in this analysis. The primary outcome was the diagnostic accuracy of rSO2 for the prediction of POCI. Results: 33 patients (57.9%) developed POCI on postoperative day. The SampEn values of rSO2 were significantly higher in the POCI group (p < 0.05). SampEn remained an independent predictor of POCI in multivariate analysis. The area under the ROC curve (AUC) value of SampEn of rSO2 for POCI were 0.706 (95% CI, 0.569–0.843; p = 0.008). Addition of preoperative MoCA assessment and blood pressure-lowering treatment increased the AUC to 0.808 (95% CI, 0.697–0.919; p < 0.001). Conclusions: The SampEn value of rSO2 showed promise as a predictor of POCI. Non-linear analysis could be used as a supplementary method for intraoperative physiological signals.

Cerebral Oximetry During Adult Cardiac Surgery Is Associated With Improved Postoperative Outcomes

To examine the association/effect of intraoperative cerebral oximetry (CeOx) on major organ morbidity and mortality (MOMM) after adult cardiac surgery. A retrospective, multicenter cohort study. Patients treated at any hospital within the Society of Thoracic Surgeons Adult Cardiac Surgery Database between July 1, 2011, and December 31, 2016, with a 30-day postoperative follow-up. Individuals ≥18 years old undergoing isolated coronary artery bypass graft (CABG) or valve repair or replacement, or any combination of procedures with cardiopulmonary bypass. Intraoperative CeOx. MOMM includes operative mortality, stroke, renal failure, prolonged mechanical ventilation, deep sternal wound infection, or reoperation for any reason within 30 days. Of 1.19 million patients who met inclusion criteria within 1,180 facilities, ∼30% (n=361,124) received CeOx versus nonrecipients (n=838,675) with similar baseline patient characteristics. Using a propensity score-based 1:1 greedy matching method, 99.7% of CeOx recipients (n=360,285) were matched with nonrecipients. The rates of MOMM were lower with versus without CeOx. The absolute risk reduction translated to a number needed to treat of 227 patients (95% CI: 166-363, p < 0.0001). In sensitivity analyses of prespecified subgroups, the benefit was strongest among patients undergoing aortic valve repair or replacement ± CABG (more than 7 fewer MOMM events per 1,000, p < 0.0001). However, intensive care unit stay >72 hours was higher with CeOx. Intraoperative cerebral oximetry is associated with less major organ morbidity and mortality after adult cardiac surgery. A large-scale clinical trial is warranted, given that desaturation is common and correctable.

Multicenter study: outcomes of carotid endarterectomy depending on configuration of circle of Willis

BACKGROUND: The circle of Willis (CW) is an important network of collaterals that provide compensatory redistribution of hemodynamic load. Several studies showed that the CW is open in approximately 50%90% of cases, and the number of missing segments correlates with low brain tolerance to ischemia in internal carotid artery (ICA) compression. Currently, studies dedicated to the relationship of different configurations of CW with the risk of ischemic brain damage.&#x0D; AIM: The analyze the immediate results of eversion carotid endarterectomy (CEA) in patients with different configurations of the structure of the CW.&#x0D; MATERIALS AND METHODS: We included 641 patients with hemodynamically significant stenosis of the internal carotid arteries (ICA) in a study period from 2010 to 2020. All patients underwent multispiral computed tomography with angiography of the extracranial and CW arteries. Based on the structural variants of the CW, six groups of patients were studied: group 1 (64.9%, n = 416) closed posterior part (CPP) with the existence of posterior communicative artery (PCA) and P1 segment of the posterior cerebral artery (PCerA); group 2 (27%, n = 173) an intermediate structure of the posterior part (IPP) with hypoplasia of the PCA or PCerA; group 3 (8.1%, n = 52) open posterior part (OPP) with the absence of PCA or PCerA; group 4 (85.95%, n = 551) closed anterior part (CAP) with the presence of the anterior communicating artery (ACA) and A1 segment of the anterior cerebral artery (ACerA); group 5 (7.95%, n = 51) an intermediate structure of the anterior part (IAP) with hypoplasia of ACA or ACerA; group 6 (6.1%, n = 39) open anterior part (OAP) with the absence of ACA or ACerA. To assess the compensatory potentials of the brain, all patients underwent measurement of the retrograde pressure in the ICA and intraoperative cerebral oximetry.&#x0D; RESULTS: In the postoperative period, 1 death was recorded in group 4 (CAP) due to a hemorrhagic transformation in the zone of ischemic stroke, on the background development of hyperperfusion syndrome. The largest number of ischemic strokes of the cardioembolic subtype was diagnosed in the ACerA territory in the presence of an unstable atherosclerotic plaque: group 1 (CPP) 0%; group 2 (IPP) 0%; group 3 (OPP) 0.24%, n = 1; group 4 (CAP) 0.18%, n = 1; group 5 (IAP) 1.96%, n = 1; group 6 (OAP) 5.1%, n = 2; p 0.9999. The probable cause was embolization against the background increase in the arterial pressure before ICA clamping. In turn, the majority of ischemic strokes of the hemodynamic subtype developed in the territory of PCerA: group 1 (CPP) 0%; group 2 (IPP) 1.73%, n = 3; group 3 (OPP) 3.8%, n = 2; group 4 (CAP) 0.18%, n = 1; group 5 (IAP) 0%; group 6 (OAP) 2.56%, n = 1; p 0.9999. This pattern coincided with the largest number of patients with CW of the IPP and OPP types among all open variants of the structure.&#x0D; CONCLUSION: Parameters of retrograde pressure in the ICA and intraoperative cerebral oximetry do not always demonstrate the need for a temporary shunt (TS). Due to the opened structure of CW, the redistribution of blood flow occurs with the formation of zones of hypo- and hyperperfusion, causing ischemic alterations in the brain matter. Thus, in order to maintain adequate cerebral hemodynamics, to mitigate the effect of hypo- and hyperperfusion, and reduce the risk of ischemic stroke, the open variant of the CW structure should be considered as an indication for a TS.

Surgical Repair of Complex Distal Internal Common Carotid Artery Aneurysm

<h3>Introduction</h3> Carotid artery aneurysms are a rare occurrence with potentially severe complications including neurological symptoms from embolization and rarely rupture. They comprise between 0.4%-4% of all peripheral aneurysms and are between 0.1%-3.7% of carotid procedures at major centers. The following is a discussion of one such procedure for a complex right common carotid with distal extension into the internal carotid artery. <h3>Methods/Results</h3> Patient was a 64-year-old male with incidental finding of right common and internal carotid artery aneurysm and occlusion of the contralateral side seen on Computer Tomography scan. Based on the patient's age and anatomy the decision was made to proceed with an open repair of the aneurysm. Due to the distal location of the internal catrotid aneurysm adequate exposure was achieved using general nasotracheal anesthesia and ligation of the occipital artery. The oral maxillofacial surgeon was on standby for possible mandible dissection; however, this was unnecessary. The reconstruction was performed using reversed femoral vein. An Argyle shunt was used to bypass the aneurysm to maintain blood flow through the internal carotid artery. An ulcerated region of the aneurysm was resected and the distal and proximal anastomosises were created. The external carotid artery was then ligated and a carotid duplex ultrasound performed intraoperatively revealed satisfactory endpoints and no evidence of significant stenosis. Upon awakening the patient, a brief neurological exam showed no deficits.Figure 1CTA of AneurysmFigure 1Figure 23D Reconstruction of CTFigure 2Figure 3Intraoperative Image Prior to BypassFigure 3Figure 4Intraoperative Image After BypassFigure 4Figure 5Follow Up Ultrasound at 4 WeeksFigure 5 Intraoperative cerebral oximetry and neuromonitoring were used throughout the procedure. Immediately post-operation the patient had transient hypoparesis which had resolved at 4 week follow up. <h3>Conclusion</h3> Carotid artery aneurysms, although rare, have a mortality rate up to 70% and a stroke rate greater than 50%; therefore, surgical intervention is the treatment of choice, with open intervention being the most common. This case demonstrates that even with an occluded contralateral carotid artery and a complex aneurysm with distal extension, carotid bypass can be done safely using stents and adequate neuromonitoring.

Intraoperative cerebral oximetry in open heart surgeries reduced postoperative complications: A retrospective study

Cardiothoracic surgeries are life-saving procedures but often it results in various complications. Intraoperative cerebral oximetry monitoring used to detect regional cerebral oxygen saturation (rScO2) is a non-invasive method that provides prognostic importance in cardiac surgery. The main aim of the present study was to evaluate the association of intraoperative cerebral oxygen monitoring during cardiac surgery on postoperative complications. This was a case-controlled retrospective study conducted on adult patients, who underwent open-heart surgery in National Heart Institute, Malaysia. The case group comprised patients on protocolized cerebral oximetry monitoring. They were treated using a standardized algorithm to maintain rScO2 not lower than 20% of baseline rScO2. The control group comprised patients with matched demographic background, preoperative risk factors, and type of surgical procedures. Propensity score stratification was utilized to contend with selection bias. Retrospective analysis was performed on 240 patients (case group) while comparing it to 407 patients (control group). The non-availability of cerebral oximetry monitoring during surgery was the prominent predictor for all outcome of complications; stroke (OR: 7.66), renal failure needing dialysis (OR: 5.12) and mortality (OR: 20.51). Postoperative complications revealed that there were significant differences for risk of mortality (p<0.001, OR = 20.51), renal failure that required dialysis (p<0.001, OR = 5.12) and stroke (p <0.05, OR = 7.66). Protocolized cerebral oximetry monitoring during cardiothoracic surgeries was found to be associated with lower incidence of stroke, renal failure requiring dialysis and mortality rate.

The relationship between intraoperative cerebral oximetry and postoperative delirium in patients undergoing off-pump coronary artery bypass graft surgery: a retrospective study

BackgroundCerebral oximetry has been widely used to measure regional oxygen saturation in brain tissue, especially during cardiac surgery. Despite its popularity, there have been inconsistent results on the use of cerebral oximetry during cardiac surgery, and few studies have evaluated cerebral oximetry during off pump coronary artery bypass graft surgery (OPCAB).MethodsTo evaluate the relationship between intraoperative cerebral oximetry and postoperative delirium in patients who underwent OPCAB, we included 1439 patients who underwent OPCAB between October 2004 and December 2016 and among them, 815 patients with sufficient data on regional cerebral oxygen saturation (rSO2) were enrolled in this study. We retrospectively analyzed perioperative variables and the reduction in rSO2 below cut-off values of 75, 70, 65, 60, 55, 50, 45, 40, and 35%. Furthermore, we evaluated the relationship between the reduction in rSO2 and postoperative delirium.ResultsDelirium occurred in 105 of 815 patients. In both univariable and multivariable analyses, the duration of rSO2 reduction was significantly longer in patients with delirium at cut-offs of < 50 and 45% (for every 5 min, adjusted odds ratio (OR) 1.007 [95% Confidence interval (CI) 1.001 to 1.014] and adjusted OR 1.012 [1.003 to 1.021]; p = 0.024 and 0.011, respectively). The proportion of patients with a rSO2 reduction < 45% was significantly higher among those with delirium (adjusted OR 1.737[1.064 to 2.836], p = 0.027).ConclusionsIn patients undergoing OPCAB, intraoperative rSO2 reduction was associated with postoperative delirium. Duration of rSO2 less than 50% was 40% longer in the patients with postoperative delirium. The cut-off value of intraoperative rSO2 that associated with postoperative delirium was 50% for the total patient population and 55% for the patients younger than 68 years.

The relationship between intraoperative cerebral oximetry and postoperative delirium in patients undergoing off-pump coronary artery bypass graft surgery

Introduction Cerebral oximetry has been widely used to measure regional oxygen saturation in brain tissue, especially during cardiac surgery. Despite its popularity, there have been inconsistent results on the use of cerebral oximetry during cardiac surgery, and few studies have evaluated cerebral oximetry during off pump coronary artery bypass graft surgery (OPCAB). Methods To evaluate the relationship between intraoperative cerebral oximetry and postoperative delirium in patients who underwent OPCAB, we included 1,439 patients who underwent OPCAB between October 2004 and December 2016 and among them, 815 patients with sufficient data on regional cerebral oxygen saturation (rSO2) were enrolled in this study. We retrospectively analysed perioperative variables and the reduction in rSO2 below cut-off values of 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, and 35%. Furthermore, we evaluated the relationship between the reduction in rSO2 and postoperative delirium. Results Delirium occurred in 105 of 815 patients. In both univariable and multivariable analyses, the duration of rSO2 reduction was significantly longer in patients with delirium at cut-offs of Discussion In patients undergoing OPCAB, intraoperative rSO2 was associated with postoperative delirium. The cut-off values for intraoperative rSO2 were 50% for the total patient population and 55% for patients younger than 68 years.

American Society for Enhanced Recovery and Perioperative Quality Initiative Joint Consensus Statement on the Role of Neuromonitoring in Perioperative Outcomes: Cerebral Near-Infrared Spectroscopy.

Some neurological complications following surgery have been related to a mismatch in cerebral oxygen supply and demand that may either lead to more subtle changes of brain function or overt complications like stroke or coma. Discovery of a perioperative neurological complication may be outside the treatment window, thereby making prevention an important focus. Early commercial devices used differential spectroscopy to measure relative changes from baseline of 2 chromophores: oxy- and deoxyhemoglobin. It was the introduction of spatially resolved spectroscopy techniques that allowed near-infrared spectroscopy (NIRS)-based cerebral oximetry as we know it today. Modern cerebral oximeters measure the hemoglobin saturation of blood in a specific "optical field" containing arterial, capillary, and venous blood, not tissue oxygenation itself. Multiple cerebral oximeters are commercially available, all of which have technical differences that make them noninterchangeable. The mechanism and meaning of these measurements are likely not widely understood by many practicing physicians. Additionally, as with many clinically used monitors, there is a lack of high-quality evidence on which clinicians can base decisions in their effort to use cerebral oximetry to reduce neurocognitive complications after surgery. Therefore, the Sixth Perioperative Quality Initiative (POQI-6) consensus conference brought together an international team of multidisciplinary experts including anesthesiologists, surgeons, and critical care physicians to objectively survey the literature on cerebral oximetry and provide consensus, evidence-based recommendations for its use in accordance with the GRading of Recommendations, Assessment, Development and Evaluation (GRADE) criteria for evaluating biomedical literature. The group produced the following consensus recommendations: (1) interpreting perioperative cerebral oximetry measurements in the context of a preinduction baseline value; (2) interpreting perioperative cerebral oximetry measurements in the context of the physiologic variables that affect them; (3) using caution in comparing cerebral oximetry values between different manufacturers; (4) using preoperative cerebral oximetry to identify patients at increased risk of adverse outcomes after cardiac surgery; (5) using intraoperative cerebral oximetry indexed to preinduction baseline to identify patients at increased risk of adverse outcomes after cardiac surgery; (6) using cerebral oximetry to identify and guide management of acute cerebral malperfusion during cardiac surgery; (7) using an intraoperative cerebral oximetry-guided interventional algorithm to reduce intensive care unit (ICU) length of stay after cardiac surgery. Additionally, there was agreement that (8) there is insufficient evidence to recommend using intraoperative cerebral oximetry to reduce mortality or organ-specific morbidity after cardiac surgery; (9) there is insufficient evidence to recommend using intraoperative cerebral oximetry to improve outcomes after noncardiac surgery.

Cerebrovascular Disease and Perioperative Neurologic Vulnerability: A Prospective Cohort Study.

Background: Stroke is a devastating perioperative complication without effective methods for prevention or diagnosis. The objective of this study was to analyze evidence-based strategies for detecting cerebrovascular vulnerability and injury in a high-risk cohort of non-cardiac surgery patients.Methods: This was a single-center, prospective cohort study. Fifty patients undergoing non-cardiac surgery were recruited −25 with known cerebrovascular disease and 25 matched controls. Neurologic vulnerability was measured with intraoperative cerebral oximetry as the primary outcome. Perioperative neurocognitive testing and serum biomarker analysis (S-100β, neuron specific enolase, glial fibrillary acid protein, and matrix metalloproteinase-9) were measured as secondary outcomes.Results: Cerebral desaturation events (an oximetry decrease ≥20% from baseline or <50% absolute value for ≥3 min) occurred in 7/24 (29%) cerebrovascular disease patients and 2/24 (8.3%) controls (relative risk 3.5, 95% CI 0.81–15.2; P = 0.094). Cognitive function trends were similar in both groups, though overall scores (range: 1,500–7,197) were ~1 standard deviation lower in cerebrovascular patients across the entire perioperative period (−1,049 [95% CI −1,662, −436], P < 0.001). No significant serum biomarker differences were found between groups over time. One control patient experienced intraoperative hypoxic-ischemic injury, but no robust biomarker or oximetry changes were observed.Conclusions: Cerebrovascular disease patients did not demonstrate dramatic differences in cerebral oximetry, cognitive trajectory, or molecular biomarkers compared to controls. Moreover, a catastrophic hypoxic-ischemic event was neither predicted nor detected by any strategy tested. These findings support the need for novel research into cerebrovascular risk and vulnerability.

Optimizing cerebral oxygenation in cardiac surgery: A randomized controlled trial examining neurocognitive and perioperative outcomes

ObjectiveThe study objective was to determine whether targeted therapy to optimize cerebral oxygenation is associated with improved neurocognitive and perioperative outcomes. MethodsIn a prospective trial, intraoperative cerebral oximetry monitoring using bilateral forehead probes was performed in cardiac surgical patients who were randomly assigned to an intervention group in which episodes of cerebral oxygen desaturation (<60% for >60 consecutive seconds at either probe) triggered an intervention protocol or a control group in which the cerebral oximetry data were hidden from the clinical team, and no intervention protocol was applied. Cognitive testing was performed preoperatively and at postoperative months 3 and 6; domains studied were response speed, processing speed, attention, and memory. Perioperative outcomes studied were death, hospital length of stay, intensive care unit length of stay, postoperative day of extubation, time on mechanical ventilation, intensive care unit delirium, Sequential Organ Failure Assessment on intensive care unit admission, and intensive care unit blood transfusion. ResultsGroup mean memory change scores were significantly better in the intervention group at 6 months (0.60 [standard error, 0.30] vs −0.17 [standard error, 0.33], adjusted P = .008). However, presence, duration, and severity of cerebral desaturation were not associated with cognitive change scores. Perioperative outcomes did not differ between the intervention and control groups. ConclusionsTargeted therapy to optimize cerebral oxygenation was associated with better memory outcome in a group of cardiac surgical patients. Some aspects of the protocol other than desaturation duration and severity contributed to the observed neuroprotective effect.

Intraoperative cerebral oximetry-based management for optimizing perioperative outcomes: a meta-analysis of randomized controlled trials.

Although evidence from observational studies in a variety of clinical settings supports the utility of cerebral oximetry as a predictor of outcomes, prospective clinical trials thus far have reported conflicting results. This systematic review and meta-analysis was designed to evaluate the influence of management associated with intraoperative cerebral oximetry on postoperative outcomes. The primary outcome was postoperative cognitive dysfunction (POCD), with secondary outcomes that included postoperative delirium, length of intensive care unit (ICU) stay, and hospital length of stay (LOS). After searching the PubMed, EMBASE, Cochrane Library, Scopus, and Google Scholar databases, all randomized controlled trials (RCTs) assessing the impact of intraoperative cerebral oximetry-guided management on clinical outcomes following surgery were identified. Fifteen RCTs comprising 2,057 patients (1,018 in the intervention group and 1,039 in control group) were included. Intraoperative management guided by the use of cerebral oximetry was associated with a reduction in the incidence of POCD (risk ratio [RR] 0.54; 95% confidence interval [CI], 0.33 to 0.90; P = 0.02; I2 = 85%) and a significantly shorter length of ICU stay (standardized mean difference [SMD], -0.21 hr; 95% CI, -0.37 to -0.05; P = 0.009; I2 = 48%). In addition, overall hospital LOS (SMD, -0.06 days; 95% CI, -0.18 to 0.06; P = 0.29; I2 = 0%) and incidence of postoperative delirium (RR, 0.69; 95% CI, 0.36 to 1.32; P = 0.27; I2 = 0%) were not impacted by the use of intraoperative cerebral oximetry. Intraoperative cerebral oximetry appears to be associated with a reduction in POCD, although this result should be interpreted with caution given the significant heterogeneity in the studies examined. Further large (ideally multicentre) RCTs are needed to clarify whether POCD can be favourably impacted by the use of cerebral oximetry-guided management.

Cerebral oxygen desaturation monitored by intraoperative near-infrared spectroscopy and incidence of post-operative cognitive dysfunction: a systematic review

Background Many advances have been made in the field of anesthesia to properly protect and monitor cerebral function and oxygenation during surgery; yet the incidence of cerebral injury, including postoperative cognitive dysfunction (POCD) remains high. Cerebral oxygen saturation measured by cerebral oximetry has the potential to decrease incidence of POCD and improve patient outcomes. Objectives To synthesize the evidence on whether there is a direct relationship between cerebral oxygen desaturation using intraoperative cerebral oximetry monitoring and the incidence of post-operative cognitive dysfunction. Inclusion criteria Types of participants This review considered all patients over the age of eight years old receiving general anesthesia for any surgical procedure, as patients younger than this age usually have different anesthetic emergence and transfer processes than patients older than eight years of age. Patients with pre-existing neurologic disease including stroke, alcohol abuse, history of psychiatric disorders and emergency cases were excluded, since a baseline neurologic test cannot be performed appropriately. Type of intervention This review considered studies that examine the use of near infrared spectroscopy or cerebral oximetry as a monitor for cerebral oxygen saturation and desaturation in patients receiving general anesthesia. Types of studies This review considered randomized controlled trials, cohort studies and case-control studies. Types of outcomes The review considered studies that include measurements of postoperative neurological deficit, or postoperative cognitive dysfunction related to cerebral oxygen desaturation as outcome measures. Search strategy The search strategy aimed to find both published and unpublished studies and papers. The search was limited to the English language, beginning with the first human reported cerebral oximetry studies using near-infrared spectroscopy in 1985 through 2013. The search was performed across: CINAHL, MEDLINE, [email protected], EMBASE, Elsevier Science Direct, Mednar and ProQuest. Methodological quality Studies were critically appraised by two independent reviewers for methodological validity prior to inclusion in the review using standardized critical appraisal instruments from the Joanna Briggs Institute. Data collection Data was extracted using the standardized data extraction tools from the Joanna Briggs Institute. Data synthesis Due to the heterogeneity of the data and outcome measurements, a meta-analysis was not possible; results are presented in a narrative summary. Results Ten studies were included in the review: Two randomized controlled trials (RCT) and eight cohort studies. In eight of the studies, monitoring of cerebral oxygen saturation by cerebral oximetry was supported. Two of the studies supporting this intervention were RCTs. Three of the studies conclude that cerebral oxygen desaturation increases length of hospital stay. Conclusions Based on the included literature, maintenance of cerebral oxygen saturation monitored by cerebral oximetry has the potential to reduce incidence of POCD. Avoidance of cerebral oxygen desaturation is also associated with a reduction in postoperative complications, including decreased length of hospital stay and faster recovery. Implications for practice The use of cerebral oximetry as an adjunct monitor during general anesthesia can help the anesthesia provider reduce incidence of postoperative cognitive dysfunction. This impacts practice and patients in that reduction of cognitive decline has the potential to aid patients to recover faster, allowing them to resume activities of daily living quicker and face a potentially shorter hospital stay. Implications for research The literature for this topic consists mainly of prospective observational cohort studies. Further randomized controlled trials are needed to determine if a higher threshold for minimal cerebral oxygen levels may decrease incidence of POCD. There is still some controversy regarding this monitoring device and incidence of cognitive decline, since there is no set safe threshold allowing deviation from baseline values. Further research is also needed to determine if prevention of cerebral oxygen desaturation has any implications in overall hospital costs.

Influence of intraoperative cerebral oximetry monitoring on neurocognitive function after coronary artery bypass surgery: a randomized, prospective study†‡

Postoperative cognitive decline is common after cardiac surgery, but it is often unrecognized at the time of hospital discharge. However, it has a great impact on patient's quality of life. Cerebral oximetry with the INVOS (IN Vivo Optical Spectroscopy) system provides the possibility of non-invasive, continuous measurement of regional cerebral oxygen saturation (rSO2), which can improve patients' outcome. The aim of this study was to examine whether cerebral oximetry can decrease the incidence of cognitive decline after coronary artery bypass grafting. We have performed a prospective, randomized study with 200 patients enrolled. Patients were divided into INVOS interventional group and CONTROL group without monitoring of cerebral oximetry. A standardized interventional protocol was performed in the INVOS group to maintain rSO2 above 80% of the patient's baseline value or above 50% of the absolute value. Cognitive evaluation was performed in all patients before and 7 days after surgery. Logistic regression was used to reveal predictors of cognitive decline. The incidence of cognitive decline 7 days after surgery was significantly lower (P = 0.002) in the INVOS interventional group (28%) than in the CONTROL group (52%). Intraoperative use of INVOS monitoring was associated with lower incidence of cognitive decline (odds ratio 0.21). In addition, predictors of cognitive decline revealed by multivariate logistic regression were older age, higher EuroSCORE and SAPS II (Simplified Acute Physiology Score) values, lower educational level and persistence of preoperative atrial fibrillation. Patients with prolonged rSO2 desaturation, defined as rSO2 area under the curve (AUC) of more than 150 min% for desaturation below 20% of baseline or AUC of more than 50 min% for desaturation below 50% absolute value, had an increased risk of cognitive decline. Postoperative cognitive outcome was significantly better in patients with intraoperative cerebral oximetry monitoring. Prolonged rSO2 desaturation is a predictor of cognitive decline and has to be avoided.

A pilot study of cerebral tissue oxygenation and postoperative cognitive dysfunction among patients undergoing coronary artery bypass grafting randomised to surgery with or without cardiopulmonary bypass*.

Coronary artery bypass surgery, performed with or without cardiopulmonary bypass, is frequently followed by postoperative cognitive decline. Near-infrared spectroscopy is commonly used to assess cerebral tissue oxygenation, especially during cardiac surgery. Recent studies have suggested an association between cerebral desaturation and postoperative cognitive dysfunction. We therefore studied cerebral oxygen desaturation, defined as area under the cerebral oxygenation curve < 40% of > 10 min.%, with respect to cognitive performance at 4 days (early) and 3 months (late) postoperatively, compared with baseline, using a computerised cognitive test battery. We included 60 patients, of mean (SD) age 62.8 (9.4) years, scheduled for elective coronary artery bypass grafting, who were randomly allocated to surgery with or without cardiopulmonary bypass. Cerebral desaturation occurred in only three patients and there was no difference in cerebral oxygenation between the two groups at any time. Among patients who received cardiopulmonary bypass, 18 (62%) had early cognitive decline, compared with 16 (53%) in the group without cardiopulmonary bypass (p = 0.50). Three months after surgery, 11 patients (39%) in the cardiopulmonary bypass group displayed cognitive dysfunction, compared with four (14%) in the non-cardiopulmonary bypass group (p = 0.03). The use of cardiopulmonary bypass was identified as an independent risk factor for the development of late cognitive dysfunction (OR 6.4 (95% CI 1.2-33.0) p = 0.027. In conclusion, although cerebral oxygen desaturation was rare in our population, postoperative cognitive decline was common in both groups, suggesting that factors other than hypoxic neuronal injury are responsible.

Post-Carotid Endarterectomy Hyperperfusion Syndrome—Is It Predictable by Lack of Cerebral Reserve?

Cerebral hyperperfusion syndrome (HS) is presumed to be because of an increase in postendarterectomy flow in patients with fixed cerebral vascular reserve. Severe headache is thought to be an early sign of possible HS. An increase in partial pressure CO₂ (pCO₂) is known to cause cerebral vasodilatation and is used to evaluate the presence of cerebral reserve. A total of 45 patients undergoing carotid endarterectomy had internal carotid artery flow measured with a transonic flow probe as follows: F1, immediately after full dissection of the internal carotid artery; F2, after 30 seconds of breath holding; and F3, after restoration of flow. ΔF2-F1 and ΔF3-F2 were also evaluated. A 10% increase between F2 and F1 indicated normal cerebral reserve and between F3 and F2 indicated increased postoperative flow. Age, gender, medical comorbidities, indication for carotid endarterectomy, intraoperative cerebral oximetry values, and percentage of bilateral carotid stenosis were recorded. All patients were contacted after discharge about the presence of postoperative headache or other suggestions of HS. Fisher's exact test was used for categorical predictors and the rank-sum test for continuous predictors. Seven (16%) patients (group A) developed postoperative headache and 38 (group B) did not. No patient developed HS. No variables were associated with postoperative headache except for female gender (p = 0.005). There were no statistically significant differences in F1, F2, F3, and ΔF (F2-F1 or F3-F2) between groups A and B (there was no descriptively significant ΔF2-F1 in 17 patients). Only one of the nine patients who had no change between F2 and F1, who had a significant increase in F3, and who was thought to be at higher risk for HS developed a postoperative headache. Lack of cerebral reserve is common in patients undergoing endarterectomy. If headache is an early sign of hyperperfusion, it does not seem to be predicted by lack of cerebral reserve and an increase in postendarterectomy flow.

Role of near infrared spectroscopy in pediatric cardiac surgery

Initial interest in near infrared spectroscopy for the prevention of neurological injury during cardiac surgery focused on intra-operative cerebral oximetry monitoring to minimize the potential negative impact of cardiopulmonary bypass and various perfusion strategies. However, it has become increasingly apparent, over the past decade, that neurological function can be impacted throughout the peri-operative period, particularly in the intensive care unit environment (Ballweg et al., 2007 [1]). As a result, the application of near infrared spectroscopy has expanded beyond the operating room to a variety of clinical arenas, including the intensive care unit and even the outpatient setting. In addition, the clinical indications have expanded to include multi-site, continuous monitoring for detection of low cardiac output states and regional tissue hypoxia of tissue beds other than the cerebral circulation. The precise role for near infrared spectroscopy in the pediatric cardiac surgery population remains unclear. While there is a growing body of evidence demonstrating its correlation with other physiologic markers, such as SvO 2, currently there are limited data to support that clinical decision-making based on near infrared spectroscopy improves patient outcomes. In assessing the potential role of near infrared spectroscopy monitoring in congenital heart disease, it is important to emphasize its unique qualities, including noninvasive, continuous, and real-time measurement of regional tissue oxygen saturation, and its potential earlier, faster and more accurate physiologic assessments to direct patient care, monitor response to therapeutic intervention, and ultimately to improve long term outcomes.

PS72. Post Carotid Endarterectomy Hyperperfusion Syndrome- Is It Predictable by Lack of Cerebral Reserve?

Background: Cerebral hyperperfusion syndrome (HS) is presumed to be because of an increase in postendarterectomy flow in patients with fixed cerebral vascular reserve. Severe headache is thought to be an early sign of possible HS. An increase in partial pressure CO2 (pCO2) is known to cause cerebral vasodilatation and is used to evaluate the presence of cerebral reserve. Methods: A total of 45 patients undergoing carotid endarterectomy had internal carotid artery flow measured with a transonic flow probe as follows: F1, immediately after full dissection of the internal carotid artery; F2, after 30 seconds of breath holding; and F3, after restoration of flow. DF2� F1 and DF3� F2 were also evaluated. A 10% increase between F2 and F1 indicated normal cerebral reserve and between F3 and F2 indicated increased postoperative flow. Age, gender, medical comorbidities, indication for carotid endarterectomy, intraoperative cerebral oximetry values, and percentage of bilateral carotid stenosis were recorded. All patients were contacted after discharge about the presence of postoperative headache or other suggestions of HS. Fisher’s exact test was used for categorical predictors and the rank-sum test for continuous predictors. Results: Seven (16%) patients (group A) developed postoperative headache and 38 (group B) did not. No patient developed HS. No variables were associated with postoperative headache except for female gender (p ¼ 0.005). There were no statistically significant differences in F1, F2, F3, and DF (F2� F1 or F3� F2) between groups A and B (there was no descriptively significant DF2� F1 in 17 patients). Only one of the nine patients who had no change between F2 and F1, who had a significant increase in F3, and who was thought to be at higher risk for HS developed a postoperative headache. Conclusions: Lack of cerebral reserve is common in patients undergoing endarterectomy. If headache is an early sign of hyperperfusion, it does not seem to be predicted by lack of cerebral reserve and an increase in postendarterectomy flow.