Regional Cerebral Oxygen Saturation Research Articles

Machine learning models of cerebral oxygenation (rcSO2) for brain injury detection in neonates with hypoxic-ischaemic encephalopathy.

The present study was designed to test the potential utility of regional cerebral oxygen saturation (rcSO2) in detecting term infants with brain injury. The study also examined whether quantitative rcSO2 features are associated with grade of hypoxic ischaemic encephalopathy (HIE). We analysed 58 term infants with HIE (>36weeks of gestational age) enrolled in a prospective observational study. All newborn infants had a period of continuous rcSO2monitoring and magnetic resonance imaging (MRI) assessment during the first week of life. rcSO2Signals were pre-processed and quantitative features were extracted. Machine-learning and deep-learning models were developed to detect adverse outcome (brain injury on MRI or death in the first week) using the leave-one-out cross-validation approach and to assess the association between rcSO2 and HIE grade (modified Sarnat-at 1h). The machine-learning model (rcSO2 excluding prolonged relative desaturations) significantly detected infant MRI outcome or death in the first week of life [area under the curve (AUC)=0.73, confidence interval (CI)=0.59-0.86, Matthew's correlation coefficient=0.35]. In agreement, deep learning models detected adverse outcome with an AUC=0.64, CI=0.50-0.79. We also report a significant association between rcSO2 features and HIE grade using a machine learning approach (AUC=0.81, CI=0.73-0.90). We conclude that automated analysis of rcSO2 using machine learning methods in term infants with HIE was able to determine, with modest accuracy, infants with adverse outcome. De novo approaches to signal analysis of NIRS holds promise to aid clinical decision making in the future. KEY POINTS: Hypoxic-induced neonatal brain injury contributes to both short- and long-term functional deficits. Non-invasive continuous monitoring of brain oxygenation using near-infrared- spectroscopy offers a potential new insight to the development of serious injury. In this study, characteristics of the NIRS signal were summarised using either predefined features or data-driven feature extraction, both were combined with a machine learning approach to predict short-term brain injury. Using data from a cohort of term infants with hypoxic ischaemic encephalopathy, the present study illustrates that automated analysis of regional cerebral oxygen saturation rcSO2, using either machine learning or deep learning methods, was able to determine infants with adverse outcome.

Utilization of NIRS Monitor to Compare the Regional Cerebral Oxygen Saturation Between Dexmedetomidine and Propofol Sedation in Mechanically Ventilated Critically ill Patients with Sepsis- A Prospective Randomized Control Trial.

Delirium frequently occurs in the acute phase of sepsis and is associated with increased ICU and hospital length of stay, duration of mechanical ventilation, and higher mortality rates. We utilized the Near-Infrared Spectroscopy monitor to measure and compare the regional cerebral oxygen saturation in mechanically ventilated patients of sepsis receiving either dexmedetomidine or propofol sedation and assessed the association between delirium and regional cerebral oxygen saturation. A single center prospective randomized control trial conducted over a period of two years, 54 patients were included, equally divided between propofol and dexmedetomidine groups. Patients received a blinded study drug, propofol (10 mg/mL) or dexmedetomidine (5 mcg/mL) via infusion pump according to randomization. Infusion rates were adjusted every 10 min based on weight-based titration tables, aiming for target sedation (RASS -2 to 0). Management components included pain monitoring using the CPOT score and delirium assessment using CAM-ICU score. Dexmedetomidine group showed higher mean regional cerebral oxygen saturation as compared to propofol group (P = .036). No significant differences were found in mechanical ventilation or ICU stay durations, delirium-free days, or sedation cessation reasons. Delirium occurred in 36 patients, with lower mean regional cerebral oxygen saturation as compared to non-delirious patients. The dexmedetomidine group had higher regional cerebral oxygen saturation compared to the propofol group. Delirious patients showed lower cerebral oxygen saturation than non-delirious patients, suggesting a link between sedation type, cerebral oxygenation, and delirium.CTRI registration: REF/2021/11/048655 N.

High-altitude cerebral oxygen saturation detection using wireless wearable cerebral oximeter.

Hypobaric hypoxic conditions encountered at high altitudes can significantly impact the physiological functions of human body. Therefore, accurate and real-time monitoring of physiological characteristics is crucial for the prevention of brain injuries in individuals with acute and chronic high-altitude exposure. In this study, a wireless wearable cerebral oximeter (WORTH band) was used for the continuous, real-time monitoring of physiological parameters, including regional cerebral oxygen saturation (rSO2) and heart rate (HR), among subjects with high-altitude exposure. During the high-altitude (from 46 m to 4300 m) expedition task, there was a significant decrease in rSO2 accompanied by a corresponding increase in heart rate as the altitude increased. Additionally, during the long-term (52 days) high-altitude (from 356 m to 4658 m) cycling task, the altitudes were significantly correlated with the rSO2 and SpO2 in the elderly subjects. The current findings indicate that the WORTH band oximeter can serve as a promising instrument for measuring rSO2 at high altitudes. We hope that the insights derived from this study could contribute to the management of cerebral oxygenation for individuals with high-altitude exposure and further expand the existing understanding of brain functional detection at high altitudes.

The role of endothelial frequency in the cerebral blood flow control during neonatal asphyxia: a retrospective longitudinal study

BackgroundCerebral blood flow dynamics can be explored through analysis of endothelial frequencies. Our hypothesis posits a disparity in endothelial activity among neonates with perinatal asphyxia, stratified by the presence or absence of neuronal lesions.MethodsWe conducted a retrospective longitudinal study involving newborns treated with hypothermia for moderate to severe asphyxia. Participants were grouped based on the presence or absence of neuronal damage to investigate temporal endothelial involvement in cerebral blood flow regulation. Regional cerebral oxygen saturation (rScO2) was measured using near-infrared spectroscopy (NIRS), and temporal series were analyzed in the frequency domain, utilizing the original frequency of the INVOS™ device.ResultsThe study included 88 patients, with 53% (47/88) being male and 33% (29/88) demonstrating brain lesions on magnetic resonance imaging. Among them, 86% (76/88) had a gestational age exceeding 37 weeks according to the Ballard scale, and 81% (71/88) had a birth weight exceeding 2500 g. Cohen’s d effect size was calculated to assess differences in endothelial frequency between groups, indicating a small effect size based on cerebral MRI findings (Cohen’s d values for Day 2 = 0.2351 and Day 3 = 0.2325).ConclusionNIRS represents a valuable tool for monitoring cerebral autoregulation in neonates affected by perinatal asphyxia, underscoring the utility of assessing endothelial frequency or energy on rScO2 measured by NIRS using the original INVOS™ device frequency.

Using cerebral regional oxygen saturation and amplitude-integrated electroencephalography in neonates on extracorporeal membrane oxygenation: preliminary experience from a single center

ObjectiveThis study aims to evaluate the application value in neurological outcome of cerebral regional oxygen saturation (CrSO2) and amplitude-integrated electroencephalography (aEEG) monitoring during neonatal extracorporeal membrane oxygenation (ECMO) courses.Methods We retrospectively analyzed 18 neonates receiving veno-arterial ECMO (V-A ECMO) support at our hospital from July 2021 to December 2022. Continuous monitoring of CrSO2 and brain electrical activity was conducted using near-infrared spectroscopy (NIRS) and aEEG throughout the ECMO treatment. We collected and analyzed related clinical data.ResultsAmong the 11 survivors, 5 were categorized as the normal group (N group) and 6 as the abnormal group (AN group) based on post-ECMO brain MRI outcomes. The N group exhibited shorter time percentage of significant CrSO2 reduction (> 25% from baseline or absolute value < 40%), better fractional tissue oxygen extraction (FTOE) rates, and more stable mean percentage changes in CrSO2 compared to the AN group. Neonates in the N group predominantly showed mildly abnormal aEEG readings, with one patient displaying disrupted sleep-wake cycles. This particular patient also had more significant CrSO2 reduction and poorer FTOE compared to others in the N group. Additionally, the Test of Infant Motor Performance (TIMP) scores indicated hypoevolutism in this patient before discharge, while others in the N group had normal TIMP scores. In the AN group, 4 exhibited moderate and 2 severe aEEG abnormalities; 5 had hypoevolutism TIMP scores, and 1 with moderate aEEG abnormalities maintained a normal TIMP score, exhibiting lesser CrSO2 reduction and improved FTOE.ConclusionCrSO2 and aEEG monitoring show potential as routine assessments for neurological outcomes during neonatal ECMO. In our cohort, a tendency was observed where neonates with greater reductions in CrSO2 and more severe aEEG abnormalities experienced poorer neurological outcomes.

Usefulness of bilateral cerebral regional oxygen saturation measurements in determining selective cerebral perfusion flow rate in a pediatric patient with aortic arch stenosis: a case report

BackgroundWe report a pediatric case where bilateral regional oxygen saturation (rSO2) measurements were useful in determining the selective cerebral perfusion (SCP) flow rate.Case presentationA 9-year-old Japanese boy, 128 cm tall and weighing 25.6 kg, was scheduled for aortic arch reconstruction due to a 90–100 mmHg pressure gradient. Pediatric-sized oximetry sensors were attached to the bilateral forehead area. The rSO2 levels were 70–80% on the right and 80–90% on the left during cardiopulmonary bypass. Immediately following deep hypothermic circulatory arrest with the body temperature cooled to 25 °C, SCP was initiated from the right brachiocephalic artery at 10 mL/kg/min. As the rSO2 decreased steeply to 43–45% on the right and to 32–38% on the left, the SCP flow was increased to 15 mL/kg/min. The right rSO2 increased promptly to 50–60%, but the left rSO2 remained at 30–40%. After the SCP flow was increased to 20 mL/kg/min, bilateral rSO2 levels of 50–60% were obtained, and the SCP flow rate was maintained. The patient was transferred to the ICU postoperatively and extubated on the second postoperative day with no neurological abnormalities.ConclusionsBilateral rSO2 measurements are essential even for a pediatric patient undergoing SCP, despite the limited forehead area.

Cerebral hypoperfusion resulting from improper cannulation positioning during aortic dissection surgery: a case report

BackgroundSelective antegrade cerebral perfusion (sACP) is a crucial cerebral protection technique employed during aortic dissection surgeries involving cardiopulmonary bypass. However, postoperative neurological complications, particularly those related to cannulation issues and perfusion problems, remain a significant concern.Case PresentationThis case report details an unusual instance where a 38-year-old male patient with Marfan syndrome experienced cerebral hypoperfusion during emergency surgery for Stanford Type A aortic dissection. Despite following standard protocols, a significant drop in regional cerebral oxygen saturation (rSO2) and abnormal blood pressure fluctuations were observed shortly after initiating sACP via the innominate artery. After initial attempts to optimize perfusion flow proved ineffective, the cannulation position was adjusted, leading to improvements. Nevertheless, the patient subsequently exhibited signs of cerebral hypoperfusion and was found to have suffered a new cerebral infarction.ConclusionsThis case report underscores the importance of precise cannula placement during sACP procedures and the dire consequences that can arise from improper positioning. It emphasizes the need for continuous monitoring and prompt intervention in cases of abnormal cerebral oxygenation and blood pressure, as well as the value of considering cannulation-related issues as potential causes of postoperative neurological complications.

Effect of optimizing cerebral oxygen saturation on postoperative delirium in older patients undergoing one-lung ventilation for thoracoscopic surgery.

This randomized controlled trial investigated whether the regional cerebral oxygenation saturation (rScO2)-guided lung-protective ventilation strategy could improve brain oxygen and reduce the incidence of postoperative delirium (POD) in patients older than 65 years. This randomized controlled trial enrolled 120 patients undergoing thoracic surgery who received one-lung ventilation (OLV). Patients were randomly assigned to the lung-protective ventilation group (PV group) or rScO2-oriented lung-protective ventilation group (TPV group). rScO2 was recorded during the surgery, and the occurrence of POD was assessed. The incidence of POD 3 days after surgery-the primary outcome-was significantly lower in the TPV group (23.3% versus 8.5%). Meanwhile, the levels of POD-related biological indicators (S100β, neuron-specific enolase, tumor necrosis factor-α) were lower in the TPV group. Considering the secondary outcomes, both groups exhibited a lower oxygenation index after OLV, whereas partial pressure of carbon dioxide and mean arterial pressure were significantly increased in the TPV group. In addition, minimum rScO2 during surgery and mean rScO2 were higher in the TPV group than in the PV group. Continuous intraoperative monitoring of brain tissue oxygenation and active intervention measures guided by cerebral oxygen saturation are critical for improving brain metabolism and reducing the risk of POD.

Oxygen-Based Autoregulation Indices Associated with Clinical Outcomes and Spreading Depolarization in Aneurysmal Subarachnoid Hemorrhage.

Impairment in cerebral autoregulation has been proposed as a potentially targetable factor in patients with aneurysmal subarachnoid hemorrhage (aSAH); however, there are different continuous measures that can be used to calculate the state of autoregulation. In addition, it has previously been proposed that there may be an association of impaired autoregulation with the occurrence of spreading depolarization (SD) events. Study participants with invasive multimodal monitoring and aSAH were enrolled in an observational study. Autoregulation indices were prospectively calculated from this database as a 10s moving correlation coefficient between various cerebral blood flow (CBF) surrogates and mean arterial pressure (MAP). In study participants with subdural electrocorticography (ECoG) monitoring, SD was also scored. Associations between clinical outcomes using the modified Rankin scale and occurrence of either isolated or clustered SD were assessed. A total of 320 study participants were included, 47 of whom also had ECoG SD monitoring. As expected, baseline severity factors, such as modified Fisher scale score and World Federation of Neurosurgical Societies scale grade, were strongly associated with the clinical outcome. SD probability was related to blood pressure in a triphasic pattern, with a linear increase in probability below MAP of ~ 100 mm Hg. Multiple autoregulation indices were available for review based on moving correlations between mean arterial pressure (MAP) and various surrogates of cerebral blood flow (CBF). We calculated the pressure reactivity (PRx) using two different sources for intracranial pressure (ICP). We calculated the oxygen reactivity (ORx) using the partial pressure of brain tissue oxygen (PbtO2) from the Licox probe. We calculated the cerebral blood flow reactivity (CBFRx) using perfusion measurements from the Bowman perfusion probe. Finally, we calculated the cerebral oxygen saturation reactivity (OSRx) using regional cerebral oxygen saturation measured by near-infrared spectroscopy from the INVOS sensors. Only worse ORx and OSRx were associated with worse clinical outcomes. Both ORx and OSRx also were found to increase in the hour prior to SD for both sporadic and clustered SD. Impairment in autoregulation in aSAH is associated with worse clinical outcomes and occurrence of SD when using ORx and OSRx. Impaired autoregulation precedes SD occurrence. Targeting the optimal MAP or cerebral perfusion pressure in patients with aSAH should use ORx and/or OSRx as the input function rather than intracranial pressure.

Impact of breast milk on cortical pain response in newborns during the heel prick procedure: a randomized controlled trial

ObjectiveTo investigate the effects of breast milk on cortical pain response and behavioral response in newborns during heel-prick procedure.Study designA prospective, randomized controlled trial was conducted on healty-term newborns, undergoing heel blood sampling. Infants were randomly assigned to study group with receive orally 2 ml breast milk (n = 45) or a control group with no intervention (n = 45). A near-infrared spectroscopy device was used to monitor regional cerebral oxygen saturation (rScO2), while neonatal pain expression was assessed by Neonatal Pain, Agitation, and Sedation Scale (N-PASS).ResultsThe N-PASS score (p = 0.001) and the crying time (p = 0.017) were significantly lower in the study group compared to the control group. Although the mean rScO2 values decreased in both groups during the procedure, the percent change in rScO2 was not significant difference between two groups.ConclusionBreast milk administration decreases behavioral responses to a noxious stimulus without reducing the cortical response to pain.Clinical trial registrationThis trial was registered under ClinicalTrials.gov identifier no. NCT05961904.

Acute impact of posthemorrhagic ventricular dilatation on cerebral oxygenation in preterm infants with intraventricular haemorrhage.

To assess the effect of ventricular decompression on cerebral oxygenation in preterm neonates with intraventricular haemorrhage (IVH) and posthemorrhagic ventricular dilatation (PHVD) using near-infrared spectroscopy (NIRS). Fifty-three preterm neonates born <34 weeks' gestation between 2013 and 2023 with IVH and subsequent PHVD were prospectively included. Regional cerebral oxygen saturation (rScO2) as well as fractional cerebral tissue oxygen extraction (cFTOE) were analysed 2 weeks before and after ventricular decompression. Ventricular decompression was performed at 18 ± 6 days of life. Patients with repeated lumbar punctures prior to ventricular drainage showed consistently higher rScO2 and lower cFTOE levels 2 weeks before and after intervention compared to those without. Patients who underwent direct ventricular drainage showed an immediate increase in rScO2 levels on the day of the procedure. In patients who underwent prior lumbar punctures, ventricular decompression did not yield additional acute effects on cerebral oxygenation. Patients who underwent repeated lumbar punctures preceding ventricular drainage consistently maintained higher rScO2 and lower cFTOE levels during the study period. In these patients, ventricular decompression did not further affect cerebral oxygenation, as they already demonstrated improved cerebral hemodynamics, whereas an immediate improvement was observed in those without prior lumbar punctures.

Effect of phenylephrine versus ephedrine on the incidence of postoperative delirium in olderly adults undergoing knee arthroplasty under general anesthesia: a single-center trial

In addition to stabilizing blood pressure (BP), ephedrine and phenylephrine have distinct effects on regional cerebral oxygen saturation (rSO2). However, whether its effect on rSO2 affects the occurrence of postoperative delirium (POD) remains unclear. Therefore, the aim of this study is to compare the effects of ephedrine and phenylephrine for BP maintenance on the incidence of POD in olderly adults who underwent knee arthroplasty under general anesthesia. One hundred twenty patients who were between 60 and 90 years old and underwent knee arthroplasty were included in this study. The patients were randomly divided into two groups: the ephedrine group and the phenylephrine group. After anesthesia induction, ephedrine and phenylephrine were continuously infused to maintain the intraoperative mean arterial pressure within the normal range (baseline mean arterial pressure ± 20%). The primary outcome measures included the incidence of POD within 1–3 days after surgery. The incidence of POD on the first day after surgery was lower in the ephedrine group than in the phenylephrine group (33% vs. 7%, P < 0.001). However, there was no significant difference in the incidence of POD between the two groups on the second and third postoperative days. Compared with the phenylephrine group, the ephedrine group experienced significantly greater cardiac output (CO) and rSO2 (P < 0.05).Clinical Trials Registry: ChiCTR2200064849, principal investigator: Changjian Zheng.

Value of near-infrared spectroscopy in evaluating the risk of neonatal necrotizing enterocolitis: A systematic review and meta-analysis

PurposeRecently, near-infrared spectroscopy (NIRS) has been proposed for diagnosing patients with neonatal necrotizing enterocolitis (NEC). However, a consensus on the credibility of NIRS in evaluating NEC risk has not been reached. This meta-analysis aimed to evaluate the relationship between NEC and splanchnic regional tissue oxygen saturation (SrSO2) and cerebral regional tissue oxygen saturation (CrSO2) detected by NIRS to clarify the clinical value of NIRS in evaluating the risk of NEC. MethodsStudies using NIRS to monitor regional tissue oxygen saturation (rSO2) in neonates with NEC published in PubMed, Web of Science, Embase, and the Cochrane Library were searched from their inception to 30 July 2023. Mean difference (MD), pooled sensitivity, and pooled specificity, along with their 95 % confidence intervals (CI), were calculated, and the random-effects model was used for analysis. This study was registered with PROSPERO (no. CRD42022326783). ResultsFourteen studies including 938 neonates (172 NEC, 766 controls) were identified. SrSO2 was significantly decreased in patients with NEC (MD: -12.52, 95 % CI: −15.95, −9.08; P < 0.00001), and this decrease was observed even before the diagnosis of NEC (MD: -13.79, 95 % CI: −17.97, −9.62; P < 0.00001). The pooled sensitivity and specificity of SrSO2 were 0.80 (95 % CI: 0.69, 0.88) and 0.90 (95 % CI: 0.61, 0.98), respectively. However, no significant difference in CrSO2 was found (MD: -4.37, 95 % CI: −10.62, 1.88; P = 0.17). ConclusionsSrSO2, detected by NIRS, could be a valuable non-invasive method for differentiating NEC from non-NEC neonates. It could differentiate prior to NEC diagnosis.

Regional cerebral oxygen saturation variability and brain injury in preterm infants.

To examine whether variation of regional cerebral oxygen saturation (rScO2) within three days after delivery predicts development of brain injury (intraventricular/cerebellar hemorrhage or white matter injury) in preterm infants. A prospective study of neonates <32 weeks gestational age with normal cranial ultrasound admitted between 2018 and 2022. All received rScO2 monitoring with near-infrared spectroscopy at admission up to 72 h of life. To assess brain injury a magnetic resonance imaging was performed at term-equivalent age. We assessed the association between rScO2 variability (short-term average real variability, rScO2ARV, and standard deviation, rScO2SD), mean rScO2 (rScO2MEAN), and percentage of time rScO2 spent below 60% (rScO2TIME<60%) during the first 72 h of life and brain injury. The median [IQR] time from birth to brain imaging was 68 [59-79] days. Of 81 neonates, 49 had some form of brain injury. Compared to neonates without injury, in those with injury rScO2ARV was higher during the first 24 h (P = 0.026); rScO2SD was higher at 24 and 72 h (P = 0.029 and P = 0.030, respectively), rScO2MEAN was lower at 48 h (P = 0.042), and rScO2TIME<60% was longer at 24, 48, and 72 h (P = 0.050, P = 0.041, and P = 0.009, respectively). Similar results were observed in multivariable logistic regression. Although not all results were statistically significant, increased rScO2 variability (rScO2ARV and rScO2SD) and lower mean values of rScO2 were associated with increased likelihood of brain injury. In preterm infants increased aberration of rScO2 in early postdelivery period was associated with an increased likelihood of brain injury diagnosis at term-equivalent age.

Pain and heart rate variability in neonates receiving dexmedetomidine.

Neonates in a NICU experience pain. Based on the cardiovascular and nociceptive systems link, a Newborn Infant Parasympathetic Evaluation (NIPE) monitor was designed to assess pain. The use of α2-agonists as analgesic-sedative drugs has increased in neonates. Given their effect on the autonomic system, we hypothesized that their use may alter NIPE's measurement capacity. Data were prospectively collected. The included patients were evaluated using combined pain assessment systems. Sixteen newborns requiring sedoanalgesia underwent a total of 84 pain assessments. A good correlation was found between the NIPE-index and the COMFORT-neo and the crSO2 (cerebral regional oxygen saturation). No correlation was found in premature infants. By sedation group, the correlation remained in those receiving α2-agonist. NIPE is a reliable tool for pain assessment. Further studies in premature infants are needed. The use of α2-agonist does not alter the measuring capacity of NIPE. The correlation between NIPE-index and crSO2 was also demonstrated.

Comparison of Changes in Rso2 in Midazolam and Propofol Sedation Post Craniotomy in the Icu of H. Adam Malik Hospital

Introduction: Cerebral oxygen saturation reflects tissue perfusion in the cerebrum. Decreases in cerebral oxygen saturation are linked to longer hospital stays and cognitive impairment. Midazolam and propofol can decrease cerebral blood flow through decreasing the cerebral oxygen metabolic rate. The purpose of this research is to analyze the comparison of changes in cerebral oxygen saturation after midazolam and propofol administration in post-craniotomy patients in the ICU of Haji Adam Malik General Hospital Medan. Subject and Method: This is a randomized control trial study. Patients were divided into, Midazolam group, that given an initial dose of 0.05 mg/kg followed by a maintenance dose of 0.02-0.10 mg/kg/hour and Propofol group that given sedation with a dose of 0.3-3mg/kg/hour, with the target of the 2 groups being a Richmond Agitation-Sedation Scale (RASS) value of 0 to -2. Data analysis using unpaired T test. Results: The results for cerebral regional oxygen saturation and RASS between groups showed significant differences in right and left value (p &lt; 0.001), but there was no significant difference in RASS (p&gt;0.05) between each group at each measurement time. The results of the analysis of cerebral regional oxygen saturation and RASS between times, there was no significant difference in right and left value (p&gt;0.05), but there was a significant difference in RASS (p&lt;0.001) at each measurement time. Based on the results of the analysis carried out, it is known that there is no statistically significant difference in changes in cerebral regional oxygen saturation both right and left in changes in RASS because it is found that all data have p&gt;0.05. Conclusion: There is no change in right and left for cerebral regional oxygen saturation after administration of propofol and midazolam groups with RASS value 0 to -2 in post-craniotomy patients in the ICU of Haji Adam Malik General Hospital Medan

The Association of Cerebral Oxygen Desaturation with Postoperative Cognitive Dysfunction in Older Patients: A Review.

Postoperative cognitive dysfunction (POCD) is a neurological complication associated with surgery and anesthesia that is commonly observed in older patients, and it can significantly affect patient prognosis and survival. Therefore, predicting and preventing POCD is important. Regional cerebral oxygen saturation (rSO2) reflects cerebral perfusion and oxygenation, and decreased intraoperative cerebral oxygen saturation has been reported to increase the risk of POCD. In this review, we elucidated the important relationship between the decline in rSO2 and risk of POCD in older patients. We also emphasized the importance of monitoring rSO2 during surgery to predict and prevent adverse perioperative cognitive outcomes. The findings reveal that incorporating intraoperative rSO2 monitoring into clinical practice has potential benefits, such as protecting cognitive function, reducing perioperative adverse outcomes, and ultimately improving the overall quality of life of older adults.

Prevalence of carotid artery stenosis and intra-cranial lesions in patients with aortic arch aneurysm and its association with intraoperative regional cerebral oxygen saturation and postoperative neurological outcomes.

Although aortic aneurysm is associated with vascular aging and atherosclerosis, carotid and intracranial vascular disease prevalence in patients with aortic arch aneurysm remains unclear. Similarly, the effect of carotid and intracranial lesions on postoperative outcomes is unknown. This study aimed to investigate the prevalence of carotid artery stenosis and intracranial lesions in patients with aortic arch aneurysm and its association with intraoperative regional cerebral oxygen saturation (rScO2) and postoperative neurological outcomes, including delirium and cerebral infarction. This retrospective observational study included 133 patients with true aortic arch aneurysm who underwent preoperative magnetic resonance imaging (MRI). We evaluated the prevalence of carotid and intracranial arterial lesions. Symptomatic cerebral infarction and delirium, defined by the confusion assessment method for the intensive care unit, were evaluated for their association with preoperative cerebrovascular lesions. Additionally, changes in regional saturation of the cerebral tissue at different surgical phases were evaluated for patients with and without cerebrovascular lesions. Fifteen (11.3%) patients experienced symptomatic cerebral infarction, and 64 (48.1%) had postoperative delirium. Preoperative MRI showed old infarction, microbleeds, significant carotid artery stenosis, and intracranial lesions in 21.1%, 14.3%, 10.5%, and 7.5% of the patients, respectively. White matter hyperintensities with Fazekas scale 2 were observed in 40.6% of the patients, while Fazekas scale 3 were observed in 18.8% of the patients. Preoperative MRI findings and postoperative neurological outcomes were not significantly different. Seventy-six patients underwent rScO2 monitoring intraoperatively. Changes in rScO2 in patients with and without carotid/cerebrovascular lesions were not significantly different. However, rScO2 was significantly lower in patients who developed cerebral infarction. Significant carotid artery stenosis and intracranial lesions were observed in 10.5% and 7.5% of the patients, respectively. Although preoperative MRI findings and changes in rScO2 or postoperative outcomes showed no significant association, patients with postoperative cerebral infarction showed significantly lower rScO2 intraoperatively.

P.119 NIRS regional oxygen saturation based cerebrovascular reactivity in the recovery from moderate/severe TBI

Background: Near-infrared spectroscopy (NIRS) regional cerebral oxygen saturation (rSO2) based cerebrovascular reactivity (CVR) indicies have enable the entirely non-invasive continuous monitoring. This study aims to compare CVR in those recovering from moderate/severe TBI to a health control group. Methods: In this prospective cohort study the cerebral oxygen CVR index, COx_a (using rSO2 and arterial blood pressure), was measured in subjects with moderate/severe TBI at follow-up. COx_a was also measured in a group of healthy controls. CVR was compared within and between these groups using conventional statistics. Results: A total of 101 heathy subject were recruited for this study along with 29 TBI patients. In the health cohort COx_a was not statistically different between males and females or in the dominate and non-dominate hemisphere. The TBI cohort, COx_a was not statistically different between first and last available follow up. Surprisingly, CVR as measured by COx_a was statistically better in those recovering from TBI than in the healthy cohort. Conclusions: In the prospective cohort study, CVR as measured by NIRS based methods, was found to be more active in those recovering from TBI than in a healthy cohort. This study may indicate that, in those that survive TBI, CVR may be enhanced as a neuroprotective measure.

P.104 Prognostic value of NIRS regional oxygen saturation based cerebrovascular reactivity in TBI: a Canadian high resolution traumatic brain injury (CAHR-TBI) cohort study

Background: Near-infrared spectroscopy regional cerebral oxygen saturation (rSO2) has gained interest as a raw parameter and as a basis for measuring cerebrovascular reactivity (CVR). This study aimed to identify threshold values of rSO2 and rSO2 based CVR at which outcomes worsened following traumatic brain injury (TBI). Methods: A retrospective multi-institutional cohort study was performed. The cerebral oxygen indices, COx (using rSO2 and cerebral perfusion pressure) as well as COx_a (using rSO2 and arterial blood pressure) were calculated for each patient. 2x2 tables were created grouping patients by alive/dead and favorable/unfavorable outcomes at various thresholds of COx and COx_a as well as rSO2 itself. Chi-square values were calculated to identify the most discriminative significant threshold. Results: In the cohort of 129 patients rSO2 did not have any statistically significant threshold value. For COx and COx_a, an optimal threshold value of 0.2 was identified for both survival and favorable outcomes with values above this associated with worse outcomes. Conclusions: In this study, raw rSO2was found to contain no significant prognostic information. However, rSO2 based indices of CVR, were found to have a uniform threshold of 0.2, above which clinical outcomes worsened. This study lays the groundwork to transition to less invasive means of continuously measuring CVR.