Cerebral Oximetry Research Articles

Cerebral Overperfusion Despite Reduced Cortical Metabolism Is Associated with Postoperative Delirium in Cardiac Surgery Patients: A Prospective Observational Study.

Background: Decreased cerebral oximetry (rSO2) in cardiac surgery is associated with postoperative delirium (POD). However, interventions optimizing intraoperative rSO2 are inconclusive. Methods: In this prospective observational cohort study, the relationship between rSO2, middle cerebral artery blood flow velocity (MCAV), and processed EEG was assessed in cardiac surgery patients with and without POD. MCAV was continuously recorded by transcranial Doppler sonography (TCD), together with continuous rSO2 and bispectral index (BIS) monitoring. Cardiopulmonary bypass (CPB) flow rate was adjusted according to body surface area. The cohort was divided into the POD and control groups, according to the postoperative results of the confusion assessment method (CAM/CAM-ICU), the 4A's test (4AT), and the Delirium Observation Scale (DOS). A mixed model analysis was performed for intraoperative raw data. The cerebral autoregulation index was calculated from TCD, rSO2, and arterial pressure values. Differences in impaired autoregulation were compared using the Mann-Whitney U test. Results: A total of 41 patients were included in this study. A total of 13 patients (36.11%) developed postoperative delirium. There were no significant differences in the baseline characteristics of patients with or without POD. Patients with POD had lower BIS values during CPB (adjusted mean difference -4.449 (95% CI [-7.978, -0.925])). RSO2 was not significantly reduced in POD, (adjusted mean difference: -5.320, 95% CI [-11.508, 0.874]). In contrast, MCAV was significantly increased in POD (10.655, 95% CI [0.491, 20.819]). The duration of cerebral autoregulation impairment did not differ significantly for TCD and cerebral oximetry-derived indices (p = 0.4528, p = 0.2715, respectively). Conclusions: Our results suggest that disturbed cerebral metabolism reflects a vulnerable brain which may be more susceptible to overperfusion during CPB, which can be seen in increased MCAV values. These phenomena occur irrespectively of cerebral autoregulation.

Cerebral Oximetry: defining baseline value and desaturation cautiously

Cerebral Oximetry: defining baseline value and desaturation cautiously

Intraoperative transfontanelle ultrasonography for pediatric patients.

Cerebral blood flow (CBF) plays a vital role in delivering cerebral oxygen, and the accurate assessment of CBF is crucial for the intraoperative management of critically ill infants. Although the direct measurement of CBF is challenging, CBF velocity (CBFV) can be assessed using transcranial Doppler. Recent advances in point-of-care ultrasound have introduced brain ultrasound as a feasible intraoperative option, in which transfontanelle ultrasonography (TFU) has been applied to measure the CBFV through the anterior fontanelle. However, the intraoperative application of TFU in pediatric patients remains limited. The present review highlights the procedural aspects and clinical applications of TFU for anesthetic and intensive care management in pediatric patients. TFU facilitates the visualization of cerebral vessels and allows a noninvasive assessment of cerebral hemodynamics. The clinical significance of TFU involves its usefulness in various clinical scenarios, including monitoring CBF during cardiac surgery, assessing fluid responsiveness, and estimating intracranial pressure. TFU also enables the detection of cerebral emboli and the evaluation of anatomical abnormalities such as hydrocephalus or intracranial hemorrhage. TFU has demonstrated potential as an invaluable tool in pediatric care, despite limited familiarity among anesthesiologists. Additional research is needed to explore the associations between CBF and clinical outcomes, focusing on autoregulation, the impact of physiological changes, the associations of TFU findings with other brain monitoring tools such as electroencephalography, cerebral oximetry, and the implications of microemboli. TFU is a significant advancement and valuable tool for noninvasively assessing cerebral hemodynamics and CBF in pediatric patients with open fontanelles.

Incidence of Concurrent Cerebral Desaturation and Electroencephalographic Burst Suppression in Cardiac Surgery Patients.

Increased intraoperative electroencephalographic (EEG) burst suppression is associated with postoperative delirium. Cerebral desaturation is considered as one of the factors associated with burst suppression. Our study investigates the association between cerebral desaturation and burst suppression by analyzing their concurrence. Additionally, we aim to examine their association with cardiac surgical phases to identify potential for targeted interventions. We retrospectively analyzed intraoperative 1-minute interval observations in 51 patients undergoing cardiac surgery. Processed EEG and cerebral oximetry were collected, with the anesthesiologists blinded to the information. The associations between cerebral desaturation (defined as a 10% decrease from baseline) and burst suppression, as well as with phase of cardiac surgery, were analyzed using the Generalized Logistic Mixed Effect Model. The results were presented as odds ratio and 95% confidence intervals (CIs). A value of P < .05 was considered statistically significant. The odds of burst suppression increased 1.5 times with cerebral desaturation (odds ratio [OR], 1.52, 95% CI, 1.11-2.07; P = .009). Compared to precardiopulmonary bypass (pre-CPB), the odds of cerebral desaturation were notably higher during CPB (OR, 22.1, 95% CI, 12.4-39.2; P < .001) and post-CPB (OR, 18.2, 95% CI, 12.2-27.3; P < .001). However, the odds of burst suppression were lower during post-CPB (OR, 0.69, 95% CI, 0.59-0.81; P < .001) compared to pre-CPB. Compared to pre-CPB, the odds of concurrent cerebral desaturation and burst suppression were notably higher during CPB (OR, 52.3, 95% CI, 19.5-140; P < .001) and post-CPB (OR, 12.7, 95% CI, 6.39-25.2; P < .001). During CPB, the odds of cerebral desaturation (OR, 6.59, 95% CI, 3.62-12; P < .001) and concurrent cerebral desaturation and burst suppression (OR, 10, 95% CI, 4.01-25.1; P < .001) were higher in the period between removal of aortic cross-clamp and end of CPB. During the entire surgery, the odds of burst suppression increased 8 times with higher inhalational anesthesia concentration (OR, 7.81, 95% CI, 6.26-9.74; P < .001 per 0.1% increase). Cerebral desaturation is associated with intraoperative burst suppression during cardiac surgery, most significantly during CPB, especially during the period between the removal of the aortic cross-clamp and end of CPB. Further exploration with simultaneous cerebral oximetry and EEG monitoring is required to determine the causes of burst suppression. Targeted interventions to address cerebral desaturation may assist in mitigating burst suppression and consequently enhance postoperative cognitive function.

Comparing NIRS and Pulse Oximetry for Cerebral Oxygen Saturation During Hypoxia Testing

Objective: This study evaluates the suitability of cerebral oximetry using near-infrared spectroscopy (NIRS) compared to traditional pulse oximetry (SpO2) for measuring cerebral oxygen saturation during hypoxia testing, aiming to enhance safety during flight operations and training. Material and Methods: The study included 106 participants aged 18–60 years at the Aerospace Medicine Training Center in Königsbrück. Cerebral oxygen saturation (rSO2) and peripheral oxygen saturation (SpO2) were measured using the INVOS™ 5100C cerebral oximeter and Masimo™ MS5 pulse oximeter, respectively. Measurements were taken at baseline, during hypoxia at 25,000 feet, and post recovery. Data analysis included regression analysis, Bland–Altman plots, and concordance correlation coefficients (CCC). Ethical approval was obtained from the Hannover Medical School. Data from 100 participants were analyzed. Results: Baseline SpO2 was 97.5 ± 1.5%, and baseline rSO2 was 77.25 ± 6.4%. During hypoxia, SpO2 dropped significantly, while rSO2 showed higher values. SpO2 recovered faster than rSO2. Deviations in rSO2 between the right and left sides during hypoxia were minimal. Lin’s CCC indicated moderate to substantial concordance. NIRS measurements were more stable and less prone to disturbances, with 95 disruptions in pulse oximetry, 25 of which were potentially critical. Conclusions: NIRS is a reliable method for detecting cerebral oxygen saturation, offering significant advantages over traditional pulse oximetry in stability and reliability during hypoxia testing. NIRS is less error-prone, supporting its use for continuous monitoring in aviation settings and enhancing flight safety by providing more accurate hypoxia detection.

Web-based training and certification of clinical staff during the randomised clinical trial SafeBoosC-III

BackgroundSafeBoosC-III is a pragmatic, multinational clinical trial evaluating cerebral oximetry-guided treatment for extremely preterm infants. In total, 1601 infants were randomised across 70 sites in Asia, Europe, and USA. To enhance data quality and patient care, a web-based training program was implemented for staff. We now report on the processes.MethodsAll training modules consisted of initial learning material followed by a case-based quiz, with elaborate responses to correct as well as to wrong answers. Modules covered trial introduction, cerebral oximetry monitoring, treatment guidelines, cerebral ultrasound, and Good Clinical Practice. The introduction module was accessible in eight languages on an online platform, while language versions varied for other modules, due to different needs. Certification was earned upon module completion, relevant to the staff category. The training was not mandatory, but for motivational purposes, principal investigators continuously received local certification rate reports.ResultsA total of 926 out of 2347 staff (39%) obtained certification. Amongst 295 staff who completed the evaluation, 83% rated the program as overall good and 94% found it relevant to clinical practice. Sites exhibited varying certification rates, with 10 at 0%, 43 between 0.1 and 79.9%, and 17 exceeding 80%. There was no correlation between the rate of certification in individual sites and how often the clinical management was changed due to cerebral hypoxia nor a correlation to site-specific estimates of the intervention effect.ConclusionDespite language barriers and a low budget, our web-based training and certification program proved feasible. Only a minority of sites reached 80% certification of staff and an impact on the trial could not be detected.Trial registrationThe SafeBoosC-III trial is registered at ClinicalTrials.gov NCT03770741. The first participant was randomised in June 2019 and recruitment was completed in December 2021.

Reference values for cerebral and peripheral tissue oximetry in children: A clinical TD-NIRS study.

Current non-invasive near-infrared spectroscopy (NIRS) tissue oximetry suffers from suboptimal reproducibility over probe repositioning, hindering clinical threshold establishment. Time Domain-NIRS (TD-NIRS) offers higher precision but lacks sufficient paediatric data, preventing effective clinical application. We aimed to establish reference ranges for cerebral and mid-upper arm (MUA) tissue haemodynamics in paediatric subjects using TD-NIRS and explore correlations with auxological variables. TD-NIRS measurements were conducted acquiring data from cerebral and MUA regions with the NIRSBOX tissue oximeter. Morphological and clinically relevant information were collected to explore potential correlations with TD-NIRS derived parameters. TD-NIRS assessment was applied in 350 children (8.4 ± 5.0 years). Precision of TD-NIRS was demonstrated with standard deviations of 0.9% (StO2) and 4.2 μM (tHb) for frontotemporal cerebral cortex, and 0.8% (StO2) and 3.7 μM (tHb) for MUA. No user dependency was observed. The trends of values for cerebral and peripheral regions vary differently according to age and auxological parameters. This study reports resting-state optical and haemodynamic values for a healthy paediatric population, providing a foundation for future investigations into clinically relevant deviations in these parameters. Furthermore, correlations with anthropometric and demographic values provide valuable insights for a deeper understanding of tissue haemodynamic evolution in childhood.

Best practices for simultaneous measurement of NIRS-based cerebral and muscle oximetry during exercise

Best practices for simultaneous measurement of NIRS-based cerebral and muscle oximetry during exercise

Preoperative biomarkers associated with delayed neurocognitive recovery.

To identify baseline biomarkers of delayed neurocognitive recovery (dNCR) using monitors commonly used in anesthesia. In this sub-study of observational prospective cohorts, we evaluated adult patients submitted to general anesthesia in a tertiary academic center in the United States. Electroencephalographic (EEG) features and cerebral oximetry were assessed in the perioperative period. The primary outcome was dNCR, defined as a decrease of 2 scores in the global Montreal Cognitive Assessment (MoCA) between the baseline and postoperative period. Forty-six adults (median [IQR] age, 65 [15]; 57% females; 65% American Society of Anesthesiologists (ASA) 3 were analyzed. Thirty-one patients developed dNCR (67%). Baseline higher EEG power in the lower alpha band (AUC = 0.73 (95% CI 0.48-0.93)) and lower alpha peak frequency (AUC = 0.83 (95% CI 0.48-1)), as well as lower cerebral oximetry (68 [5] vs 72 [3], p = 0.011) were associated with dNCR. Higher EEG power in the lower alpha band, lower alpha peak frequency, and lower cerebral oximetry values can be surrogates of baseline brain vulnerability.

Neurological Complications Following Cardiac Surgery: Management and Future Directions

Neurological complications related to cardiac surgery present physicians with challenges. These complications severely impact patients’ outcomes, the quality of their lives, and affect the resources available at healthcare centers. The treatment of neurological complications requires a multidisciplinary approach, where evidenced-based interventions work to identify the patient profiles and risk factors. In addition, ongoing investigations on alternative treatment methods like cerebral oximetry and personalized risk stratification may likely improve management and outcomes of such high-risk patients. Based on the significance that neurological problems play after cardiac surgery, this paper intends to offer the practitioners and scientists vital insights to help them provide the most suitable healthcare to the affected patients and to guide future studies.

Cerebral oximetry in high-risk surgical patients: where are we?

This review aims to summarize the latest evidence on the role of near-infrared spectroscopy (NIRS) in monitoring cerebral oxygenation in high-risk surgical patients, including both cardiac and noncardiac surgeries, and to present a new algorithm for its application. NIRS effectively measures brain oxygen saturation noninvasively, proving valuable in cardiac surgeries to reduce neurological complications, though its impact on nonneurological outcomes is less clear. In noncardiac surgeries, NIRS can help prevent complications like postoperative cognitive dysfunction, particularly in high-risk and major surgeries. Studies highlight the variability of cerebral oxygenation impacts based on surgical positions, with mixed results in positions like the beach chair and sitting positions. A structured algorithm for managing cerebral desaturation has been proposed to optimize outcomes by addressing multiple factors contributing to blood oxygen content and delivery. Despite its limitations, including spatial resolution and interindividual variability, NIRS is a useful tool for intraoperative cerebral monitoring. Further studies are needed to confirm its broader applicability in noncardiac surgeries, but current evidence supports its role in reducing postoperative complications especially in cardiac surgeries.

Monitoring of Cerebral Blood Flow Autoregulation after Cardiac Arrest.

Background: Cardiac arrest remains one of the leading causes of death. After successful resuscitation of patients in cardiac arrest, post-cardiac arrest syndrome develops, part of it being an impaired cerebral blood flow autoregulation. Monitoring cerebral blood flow autoregulation after cardiac arrest is important for optimizing patient care and prognosticating patients' survival, yet remains a challenge. There are still gaps in clinical implications and everyday use. In this article, we present a systematic review of studies with different methods of monitoring cerebral blood flow autoregulation after non-traumatic cardiac arrest. Methods: A comprehensive literature search was performed from 1 June 2024 to 27 June 2024 by using multiple databases: PubMed, Web of Science, and the Cochrane Central Register of Controlled Trials. Inclusion criteria were studies with an included description of the measurement of cerebral blood flow autoregulation in adult patients after non-traumatic cardiac arrest. Results: A total of 16 studies met inclusion criteria. Our data show that the most used methods in the reviewed studies were near-infrared spectroscopy and transcranial Doppler. The most used mathematical methods for calculating cerebral autoregulation were cerebral oximetry index, tissue oxygenation reactivity index, and mean flow index. Conclusions: The use of various monitoring and mathematical methods for calculating cerebral blood flow autoregulation poses a challenge for standardization, validation, and daily use in clinical practice. In the future studies, focus should be considered on clinical validation and transitioning autoregulation monitoring techniques to everyday clinical practice, which could improve the survival outcomes of patients after cardiac arrest.

An Innovative Approach in Emergency Medicine: Monitoring Brain Oxygenation with Cerebral Oximetry

The monitoring of cerebral oxygenation is a method that is not commonly integrated into the majority of existing emergency departments(ED), but it has attracted increasing attention, particularly in recent years. As the severity of ischemia escalates during cardiopulmonary resuscitation(CPR), the probability of both survival and favorable neurological outcomes diminishes. Therefore, the imperative development of methods to quantify the magnitude of ischemia, particularly cerebral ischemia, during resuscitation is critical for enhancing overall outcomes. Cerebral oximetry, using near-infrared spectroscopy, represents a noninvasive method for measuring brain oxygenation. The objective of this manuscript is to present an overview of the application of cerebral oximetry in the ED.

Investigating the Relationship Between Cerebral Oximetry and Arterial Blood Gas Parameters

Cerebral oximetry, employing near-infrared spectroscopy (NIRS) through a transcutaneous membrane, is a non-invasive monitoring method designed to assess average regional tissue oxygenation in the frontal cortex. The literature consistently underscores its invaluable role in gauging cerebral tissue oxygen levels throughout the perioperative period. Notably, guidelines routinely recommend the use of NIRS in adult cardiac surgery. In contrast, arterial blood gas analysis remains a standard practice in cardiac surgery to measure general systemic oxygenation. While arterial blood gas analysis provides insights into overall systemic oxygenation, NIRS focuses specifically on regional oxygenation within the brain tissue. This paper delves into the intricate relationship between NIRS and arterial blood gas parameters, shedding light on their correlation and significance in the context of assessing oxygenation levels.

How Surgical Positions Affect Cerebral Oxygenation

How Surgical Positions Affect Cerebral Oxygenation? This study investigates the use of cerebral oximetry in various surgical positions and its impact on cerebral oxygenation. We conducted a literature review through Medline, and Ebscohost, focusing on articles published until October 30, 2023. Our findings indicate that: • Cerebral oxygenation is affected by all surgical positions, with the most significant clinical impact observed in the seated position. • Maintaining cerebral autoregulation is crucial for preventing cerebral hypoxia or desaturation. Upholding a mean arterial pressure above 60 mmHg is essential for this purpose. • Anesthesia can negatively impact cerebral oxygenation by potentially impairing cerebral autoregulation. • Inhalation anesthetics may have a more beneficial effect on cerebral oxygenation compared to intravenous anesthetics. • The risk of cerebral desaturation increases in elderly patients and those with comorbidities. • Standardization of cerebral desaturation definitions is needed to better assess its relationship with postoperative complications. • The position of the blood pressure transducer can affect the accuracy of intraoperative monitoring. In the seated position, placing it at the level of the acoustic meatus provides a more precise assessment. Our study highlights the importance of considering the effects of different surgical positions on cerebral oxygenation. This knowledge can assist anesthesiologists in monitoring patients intraoperatively and potentially preventing postoperative neurological complications. Keywords: Cerebral oximetry, Beach chair, cerebral oxygenation, Prone, Near-infrared spectroscopy

The Role of Cerebral Oximetry in Predicting and Preventing Postoperative Cognitive Dysfunction

Postoperative Cognitive Dysfunction (POCD) is a serious problem that is frequently seen especially in elderly patients and can cause permanent cognitive decline, prolonged hospital stay, loss of independence, decreased quality of life and even mortality. Identifying individuals at risk of developing POCD can prevent this condition by enabling the development of early interventions. POCD has a multifactorial etiology, and intraoperative cerebral perfusion disorder is considered to be one of these mechanisms. Near-infrared Spectroscopy (NIRS) device provides monitoring of regional brain oxygenation. There are studies on the predictability and preventability of cognitive disorders that may develop after surgery with the use of NIRS. In this article, it is aimed to present the study results and inferences regarding the relationships between the areas of use of NIRS and the pathogenesis of POCD.

Increased impairment of cerebral autoregulation in COVID-19 associated pulmonary failure requiring extracorporeal membrane oxygenation.

Cerebrovascular complications are feared but also commonly reported in patients with COVID-19 requiring extracorporeal membrane oxygenation (ECMO) support therapy. Besides other reasons, a connection between impaired cerebral autoregulation and SARS-CoV-2 infection as a mechanism for an increase in cerebrovascular complications has been hypothesized. In an observational single-center study, we investigated a cohort of 48 patients requiring veno-venous ECMO support therapy with (n = 31) and without SARS-CoV-2 infection (n = 17). Cerebral autoregulation was assessed with the cerebral oximetry-derived autoregulation index (ORx) based on a moving correlation between arterial pressure and cerebral oximetry. Patients with ECMO support therapy and SARS-CoV-2 experienced more time with impaired cerebral autoregulation than without SARS-CoV-2 [17 ± 9 vs. 13 ± 9% (p = 0.027)]. Patients with SARS-CoV-2 suffering from cerebrovascular complications had more time with impaired autoregulation than non SARS-CoV-2 patients with these complications (19 ± 9 vs. 10 ± 4%, p = 0.032). Our results suggest a connection between SARS-CoV-2 and impaired cerebral autoregulation as well as cerebrovascular complications in SARS-CoV-2 patients.

Cerebrovascular Autoregulation in Preterm Infants Using Heart Rate or Blood Pressure: A Pilot Study.

Cerebrovascular autoregulation (CAR) is often impaired in preterm infants but requires invasive mean arterial blood pressure (MABP) measurements for continuous assessment. We aimed to assess whether using heart rate (HR) results in different CAR assessment compared with using MABP. We compared CAR (moving window correlation-coefficient with cerebral oxygenation saturation (rcSO2)), and percentage of time with impaired CAR (%timeCARi) calculated by either HR (TOHRx, tissue oxygenation heart rate reactivity index) or MABP (COx, cerebral oximetry index) during the first 72 h after birth, and its association with short-term cerebral injury. We included 32 infants, median gestational age of 25 + 5/7 weeks (interquartile range 24 + 6/7-27 + 5/7). COx and TOHRx correlation coefficients (cc) were significantly different in the first two days after birth (individual means ranging from 0.02 to 0.07 and -0.05 to 0.01). %TimeCARi using MABP (cc cut-off 0.3), was higher on day 1 (26.1% vs. 17.7%) and day 3 (23.4% vs. 16.9%) compared with HR (cc cutoff -0.3). During 65.7-69.6% of the time, both methods indicated impaired CAR simultaneously. The aforementioned calculations were not associated with early cerebral injury. In conclusion, HR and MABP do not seem interchangeable when assessing CAR in preterm infants.

Effect of Cerebral Oximetry-Guided Treatment on Brain Injury in Preterm Infants as Assessed by Magnetic Resonance Imaging at Term Equivalent Age: An Ancillary SafeBoosC-III Study

Plain Language SummaryOur study looked at whether monitoring the cerebral oxygenation by a specific tool can help protect the brains of very premature babies. We wanted to see if this tool could reduce the chances of any degree of brain injury in these tiny babies. The SafeBoosC-III was a big multicenter trial that found that using cerebral oximetry did not make a big difference in preventing severe brain injuries or saving lives in these babies. To study in more depth a representative group of babies in this big trial, we used advanced brain scans like MRI to check babies’ brain health. Even though we noticed a small improvement in overall brain health when using cerebral oximetry, it was not enough to show a clear benefit. It is important to note that only one baby out of every five had severe brain injuries in the study. Our research shows that while cerebral oximetry is helpful for monitoring brain oxygen levels, it did not lead to noticeable changes in how often brain injuries happened in premature babies. This tells us that we still have more to learn about protecting these fragile babies’ brains, and we need to keep looking for better ways to help them. In conclusion, our study highlights the challenges in using cerebral oximetry to prevent brain injuries in very premature babies, urging doctors and researchers to keep exploring new ideas to improve their brain health.

Assessing different brain oxygenation components in elderly patients under propofol or sevoflurane anesthesia: A randomized controlled study

Study objectiveElderly patients undergoing pathophysiological changes necessitate clinical tools for cerebral monitoring. This prospective randomized controlled study aimed to explore how cerebral monitoring using Δo2Hbi, ΔHHbi, and ΔcHbi manifests in elderly patients under either propofol or sevoflurane anesthesia. DesignSingle-center, prospective, randomization. SettingA single tertiary hospital (Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea). PatientsEnrolled 100 patients scheduled for urologic surgery under general anesthesia. Inclusion criteria were (a) age 70–80 years, (b) American Society of Anesthesiologists (ASA) physical status I-II. InterventionPatients were double-blind randomized to receive propofol-based or sevoflurane anesthesia. Cerebral oximetry-related parameters were measured at 5, 10, 15, 20, and 30 min in a setting devoid of surgery-related factors. MeasurementsThe primary outcome focused on the Δo2Hbi pattern in the left and right sides within the propofol and sevoflurane groups. Main resultsWe analyzed 100 patients, 50 patients in each group. In the propofol group, the left Δo2Hbi decreased from 1.4 (3.7) at 5 min to −0.1 (1.8) at 30 min (P < 0.0001), and the right Δo2Hbi decreased from 2.9 (4.2) at 5 min to −0.06 (2.3) at 30 min (P < 0.0001). In the sevoflurane group, the left Δo2Hbi decreased from 1.1 (3.4) at 5 min to −1.4 (4.4) at 30 min (P < 0.0001), and the right Δo2Hbi decreased from 2.0 (3.2) at 5 min to −1.2 (3.9) at 30 min (P < 0.0001). There were no significant differences between the two groups. ΔHHbi did not exhibit significant changes after an initial decrease at 5 min and showed no significant differences between the two groups. ConclusionsIn cerebral oximetry, Δo2Hbi and ΔHHbi could emerge as a valuable approach for discerning changes in the underlying baseline status of the brain in elderly patients during anesthesia.