Cerebral Oximetry Research Articles

The Influence of Preoperative Physical Activity on Intraoperative Brain Function in Cardiac Surgical patients.

Background Preoperative physical activity and intraoperative brain health are recognized to influence postoperative delirium (POD). Electroencephalogram (EEG) burst suppression and cerebral desaturation are indicators of abnormal intraoperative brain health. Our study aimed to investigate the associations between preoperative physical activity and intraoperative EEG burst suppression and cerebral desaturation. Methods We retrospectively analyzed data from 67 patients from one of the institutions participating in a multisite randomized controlled trial, PANDORA, involving patients undergoing cardiac surgery. The preoperative PCS12 score calculated using the SF12 questionnaire was used as an indicator of preoperative physical activity. Intraoperative EEG and cerebral oximetry data (not the current standard of care in this facility) were collected, and the anesthesiologists were blinded to the information. We analyzed the following associations between the PCS12 score and i) burst suppression duration, ii) the number of cerebral desaturations, and iii) the number of observations with concurrent cerebral desaturation and burst suppression using a generalized linear model. The results are presented as percentage changes in outcomes, and a 95% C.I. p value < 0.05 was considered to indicate statistical significance. Results Each unit increase in the PCS12 score was associated with a 3.3% decrease in the duration of burst suppression (-3.3 [-5.3, -1.2], p value = 0.002). The duration of burst suppression decreased by 29.2% with each successive quartile increase in the PCS-12 score, indicating a dose‒response relationship (-29.2 [-41.6, -16], p < 0.001). Specifically, the patients in the last three quartiles exhibited a 55.4% reduction in BSD compared to those in the first quartile (-55.4 [-74.4, -24.6], p = 0.002) (Fig. 2). We did not observe any significant association between the PCS12 score and cerebral desaturation. Conclusion Decreased preoperative physical activity, as measured by the SF-12 questionnaire, is significantly associated with increased EEG burst suppression duration. Preoperative physical activity did not show any association with cerebral desaturations and concurrent cerebral desaturation and burst suppression. Clinical Trial information ClinicalTrials.gov Identifier- NCT04093219 https://clinicaltrials.gov/ct2/show/NCT04093219 Principal Investigator - Balachundhar Subramaniam Date of registration - September 13, 2019.

Reference Ranges for Arterial Oxygen Saturation, Heart Rate, and Cerebral Oxygen Saturation during Immediate Postnatal Transition in Neonates Born Extremely or Very Preterm

ObjectiveTo define percentile charts for arterial oxygen saturation (SpO2), heart rate (HR), and cerebral oxygen saturation (crSO2) during the first 15 minutes after birth in neonates born very or extremely preterm and with favorable outcome. Study designWe conducted a secondary-outcome analysis of preterm neonates included in the COSGOD III trial with visible cerebral oximetry measurements and with favorable outcome, defined as survival without cerebral injuries until term age. We excluded infants with inflammatory morbidities within the first week after birth. SpO2 was obtained by pulse oximetry, and electrocardiogram or pulse oximetry were used for measurement of HR. CrSO2 was assessed with near-infrared spectroscopy. Measurements were performed during the first 15 minutes after birth. Percentile charts (10th to 90th centile) were defined for each minute. ResultsA total of 207 preterm neonates with a gestational age of 29.7 (23.9-31.9) weeks and a birth weight of 1200 (378-2320) grams were eligible for analyses. The 10th percentile of SpO2 at minute two, five, ten and 15 was 32%, 52%, 83% and 85%, respectively. The 10th percentile of HR at minute two, five, ten and 15 was 70bpm, 109bpm, 126bpm and 134bpm, respectively. The 10th percentile of crSO2 at minute two, five, ten and 15 was 15%, 27%, 59% and 63%, respectively. ConclusionsThis study provides new centile charts for SpO2, HR, and crSO2 for extremely preterm neonates with favorable outcome. Implementing these centiles in guiding interventions during the stabilization process after birth might help to more accurately target oxygenation during postnatal transition period.

Physiologic Determinants of Near-Infrared Spectroscopy-Derived Cerebral and Tissue Oxygen Saturation Measurements in Critically Ill Patients.

Near-infrared spectroscopy (NIRS) is a potentially valuable modality to monitor the adequacy of oxygen delivery to the brain and other tissues in critically ill patients, but little is known about the physiologic determinants of NIRS-derived tissue oxygen saturations. The purpose of this study was to assess the contribution of routinely measured physiologic parameters to tissue oxygen saturation measured by NIRS. An observational sub-study of patients enrolled in the Role of Active Deresuscitation After Resuscitation-2 (RADAR-2) randomized feasibility trial. Two ICUs in the United Kingdom. Patients were recruited for the RADAR-2 study, which compared a conservative approach to fluid therapy and deresuscitation with usual care. Those included in this sub-study underwent continuous NIRS monitoring of cerebral oxygen saturations (SctO2) and quadriceps muscle tissue saturations (SmtO2). Synchronized and continuous mean arterial pressure (MAP), heart rate (HR), and pulse oximetry (oxygen saturation, Spo2) measurements were recorded alongside NIRS data. Arterial Paco2, Pao2, and hemoglobin concentration were recorded 12 hourly. Linear mixed effect models were used to investigate the association between these physiologic variables and cerebral and muscle tissue oxygen saturations. Sixty-six patients were included in the analysis. Linear mixed models demonstrated that Paco2, Spo2, MAP, and HR were weakly associated with SctO2 but only explained 7.1% of the total variation. Spo2 and MAP were associated with SmtO2, but together only explained 0.8% of its total variation. The remaining variability was predominantly accounted for by between-subject differences. Our findings demonstrated that only a small proportion of variability in NIRS-derived cerebral and tissue oximetry measurements could be explained by routinely measured physiologic variables. We conclude that for NIRS to be a useful monitoring modality in critical care, considerable further research is required to understand physiologic determinants and prognostic significance.

Comparison of Propofol-Based Total Intravenous Anesthesia versus Volatile Anesthesia with Sevoflurane for Postoperative Delirium in Adult Coronary Artery Bypass Grafting Surgery: A Prospective Randomized Single-Blinded Study

ObjectiveDelirium and postoperative cognitive dysfunction (POCD) are major causes of morbidity after coronary artery bypass surgery (CABG) with cardiopulmonary bypass (CPB). Anesthetic agents such as propofol and sevoflurane potentially have a role in pathogenesis of cognitive dysfunction. There is scarce literature comparing these two agents in CABG with CPB despite the relatively high incidence of cognitive dysfunction in this patient population. The authors compared the incidence of delirium and early POCD (at one week) between propofol-based TIVA and volatile anesthesia with sevoflurane in adult patients undergoing elective CABG with CPB. DesignA prospective randomized single blinded study. SettingThis study was conducted at a single institution (Sree Chitra Tirunal Institute for Medical Sciences and Technology, a Tertiary care Institute and a university level teaching hospital) ParticipantsSeventy two patients undergoing elective CABG under CPB participated in this study. InterventionsThis study was conducted on 72 adult patients (> 18 years) undergoing elective CABG under CPB who were randomised to receive propofol or sevoflurane. Anesthetic depth was monitored to maintain bispectral index between 40-60. Delirium was assessed using the Confusion-Assessment Method for the intensive care unit (CAM-ICU). Early POCD was diagnosed when there was a reduction of > 2 points in the Montreal Cognitive Assessment (MoCA) score compared to baseline. Cerebral oximetry changes using near infrared spectroscopy (NIRS), atheroma grades and intraoperative variables were compared between the two groups. Measurements & Main ResultsSeventy-two patients were randomised to receive propofol (36) or sevoflurane (36). The mean age was 59.4 years (SD 8.6 years). The baseline and intraoperative variables including atheroma grades, NIRS values, hemoglobin, glycemic control, oxygenation were comparable between the two groups. Fifteen (21.7%) patients developed delirium and 31 (44.9%) had early POCD. The incidence of delirium was higher with sevoflurane (12, 34.2%) compared to propofol (3, 8.8%), OR 1.72 (95% CI: 1.13-2.62), p 0.027*. POCD was higher with sevoflurane (20, 57.1%) compared to propofol (11,32.3%), OR 1.63 (95% CI: 1.01-2.62), p value 0.038*. In patients age > 65 years, delirium was higher with sevoflurane (7/11,63.6%) compared to propofol (1/7, 14.2%), p 0.03*. ConclusionsPropofol based TIVA was associated with a lower incidence of delirium and POCD compared to sevoflurane in this cohort of patients undergoing CABG under CPB. Large scale, multi-centre, randomized trials with longer follow-up duration are needed to substantiate the clinical relevance of this observation.

Cerebral autoregulation metrics correlate with some major morbidity and mortality outcomes after cardiac surgery

Background: Personalized arterial blood pressure management based on cerebral autoregulation has shown clinical relevance in cardiac surgery. Here we explore the associations between lower limit of cerebral autoregulation (LLA) metrics and postoperative outcomes in a heterogenous and high-acuity population of patients undergoing high-risk cardiovascular surgery. Methods: Autoregulation parameters were determined retrospectively in 686 patients undergoing cardiac surgery at UAB Hospital. Cerebral oximetry index (COx) and hemoglobin volume reactivity index (HVx) determine a patient’s unique LLA by examining the correlation between mean arterial pressure (MAP) and near-infrared spectroscopy signals. Logistic regression analyses explored associations of area under the time-pressure curve and duration below LLA with stroke, acute kidney injury, operative mortality, low cardiac output syndrome, and mechanical ventilation lasting more than 48 hours. Any incidence of these outcomes was considered as the primary outcome of interest: major morbidity or operative mortality (MMOM). Results: We explored the association of Area under the time-pressure curve for pressures less than patient-specific Lower Limits of Autoregulation (AUCABP&lt;LLA: and MMOM. Results are reported with odds ratio (OR) and 95% confidence intervals (CI). AUCABP&lt;LLA was not significantly associated with MMOM incidence (HVx: Odds Ratio 1.000, 95% CI 0.970-1.030, p=0.979; COx: OR 1.006, 95% CI 0.990-1.023, p=0.456). However, for components of MMOM, specifically operative mortality (HVx: OR 1.063, 95% CI 1.013-1.115, p=0.013; COx: OR 1.027, 95% CI 1.001-1.052, p=0.038) and low cardiac output syndrome (HVx: OR 1.036, 95% CI 1.004-1.068, p=0.025), there were statistically significant relationships with AUCABP&lt;LLA when controlling for logistic Euroscore and preoperative hemoglobin levels. Conclusions: Area under the time-pressure curve for pressures less than patient-specific LLA was not significantly associated with MMOM incidence. However, we found significant associations between components of MMOM, specifically operative mortality and low cardiac output syndrome, with an AUCABP&lt;LLA and time under LLA. These results suggest that LLA metrics might have utility in predicting specific postoperative outcomes, but their role in predicting overall MMOM may be limited in heterogenous and high-acuity patient populations. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Unilateral versus bilateral cerebral oximetry in delirium prevention during CABG and valve surgery

Unilateral versus bilateral cerebral oximetry in delirium prevention during CABG and valve surgery

Integrating rSO2 and EEG monitoring in cardiopulmonary resuscitation: A novel methodology

Despite improvements in cardiopulmonary resuscitation (CPR), survival and neurologic recovery after cardiac arrest remain poor due to ischemia and subsequent reperfusion injury. As the likelihood of survival and favorable neurologic outcome decreases with increasing severity of ischemia during CPR, developing methods to measure the magnitude of ischemia during resuscitation is critical for improving overall outcomes. Cerebral oximetry, which measures regional cerebral oxygen saturation (rSO2) by near‐infrared spectroscopy, has emerged as a potentially beneficial marker of cerebral ischemia during CPR. In numerous preclinical and clinical studies, higher rSO2during CPR has been associated with improved cardiac arrest survival and neurologic outcome. There is also emerging evidence that this can be integrated with electroencephalogram (EEG) monitoring to provide a bimodal system of brain monitoring during CPR. In this method’s review, we discuss the feasibility, application, and implications of this integrated monitoring approach, highlighting its significance for improving clinical outcomes in cardiac arrest management and guiding future research directions.

Navigating a grey zone: Neuromonitoring in the management of temporary internal carotid artery occlusion techniques - A case series and literature review

There is a dearth of clearly defined thresholds to guide the application of neuromonitoring modalities in temporary vessel occlusion techniques. We report a case series exploring the utility of various neuromonitoring techniques during temporary vessel occlusion procedures. We conducted a retrospective chart review of patients, who underwent temporary vessel occlusion procedures over a two-year period and examined the neuromonitors employed in temporary vessel occlusion procedures including balloon occlusion test (BOT). We found complete details of nine patients, who were managed with the use of the following neuromonitors: cerebral oximetry, electrical activity monitors, evoked potential monitors, and transcranial Doppler. A literature search identified other studies reporting utilization of adjuvant neuromonitoring in these procedures. Although multiple sensors could be concurrently attached to patients without impeding image acquisition in patients undergoing BOT, our review of the literature and our own findings revealed a lack of consistent correlation with outcome, particularly concerning near-infrared spectroscopy values.

Shining a light on cerebral autoregulation: Are we anywhere near the truth?

The near-infrared spectroscopy (NIRS)-derived cerebral oximetry index (COx) has become popularized for non-invasive neuromonitoring of cerebrovascular function in post-cardiac arrest patients with hypoxic-ischemic brain injury (HIBI). We provide commentary on the physiologic underpinnings and assumptions of NIRS and the COx, potential confounds in the context of HIBI, and the implications for the assessment of cerebral autoregulation.

Alternative consent methods used in the multinational, pragmatic, randomised clinical trial SafeBoosC-III

BackgroundThe process of obtaining prior informed consent for experimental treatment does not fit well into the clinical reality of acute and intensive care. The therapeutic window of interventions is often short, which may reduce the validity of the consent and the rate of enrolled participants, to delay trial completion and reduce the external validity of the results. Deferred consent and ‘opt-out’ are alternative consent methods. The SafeBoosC-III trial was a randomised clinical trial investigating the benefits and harms of cerebral oximetry monitoring in extremely preterm infants during the first 3 days after birth, starting within the first 6 h after birth. Prior, deferred and opt-out consent were all allowed by protocol.This study aimed to evaluate the use of different consent methods in the SafeBoosC-III trial, Furthermore, we aimed to describe and analyse concerns or complaints that arose during the first 6 months of trial conduct.MethodsAll 70 principal investigators were invited to join this descriptive ancillary study. Each principal investigator received a questionnaire on the use of consent methods in their centre during the SafeBoosC-III trial, including the possibility to describe any concerns related to the consent methods used during the first 6 months of the trial, as raised by the parents or the clinical staff.ResultsData from 61 centres were available. In 43 centres, only prior informed consent was used: in seven, only deferred consent. No centres used the opt-out method only, but five centres used prior and deferred, five used prior, deferred and opt-out (all possibilities) and one used both deferred and opt-out. Six centres applied to use the opt-out method by their local research ethics committee but were denied using it. One centre applied to use deferred consent but was denied. There were only 23 registered concerns during the execution of the trial.ConclusionsConsent by opt-out was allowed by the protocol in this multinational trial but only a few investigators opted for it and some research ethics boards did not accept its use. It is likely to need promotion by the clinical research community to unfold its potential.

Impact of catheterized ductal closure on renal and cerebral oximetry in premature neonates.

Percutaneous catheter-based closure is increasingly utilized in premature newborns. While near-infrared spectroscopy (NIRS) has been examined for assessment of interventional closure in surgical ligation, its application in percutaneous transcatheter closure remains unexplored. This study aims to assess cerebral and renal hemodynamic changes using NIRS during percutaneous closure compared to surgical closure in preterm infants. A prospective observational study enrolled preterm infants born at 32 weeks of gestation or less and diagnosed with hsPDA between January 2020 and December 2022. These infants received either surgical or catheter-based closure of the PDA. Cerebral and renal oxygen saturation was monitored using the INVOS 5100 device from 12 h before the intervention until 24 h after. Linear mixed-effects models were used to analyze time-dependent variables. Twenty-two patients were enrolled, with catheter-based closure performed in 16 cases and conventional surgery in 6 cases. Following ductal closure, a significant increase in renal and cerebral oximetry was observed alongside a decrease in renal and cerebral tissue oxygen extraction. These changes were particularly pronounced in the renal territory. No differences were detected between catheterization and surgical closure. Conclusion: An improvement in cerebral and renal oximetry following hsPDA closure was observed. However, we did not identify differences in this pattern based on the type of interventional procedure for PDA, whether surgery or catheterization. What is Known: •The presence of a significant ductus is common in premature patients. Studies have shown that it affects cerebral and renal hemodynamics negatively, leading to decreased oximetry values in these areas. It has been reported that closure of the ductus, either pharmacologically or surgically, results in improved oximetry values. What is New: •This study assess the impact of percutaneous closure of ductus, revealing increased oximetry values in cerebral and renal territories without significant differences compared to surgical ligation. Notably, renal oximetry values showed a greater increase, underscoring the importance of multi-location monitoring.

393 Cerebral Oximetry Using the USIC Protocol Is a Reliable Tool for Indicating Selective Intraluminal Shunting During Carotid Endarterectomy

INTRODUCTION: Indication to selective shunting during carotid endarterectomy (CEA) is based on monitoring during the procedure. Cerebral oximetry (CO) using near-infrared spectroscopy (NIRS) is one of the monitoring tools but no clear cut off value for an intraluminal shunt insertion has been established. METHODS: 125 patients underwent CEA under LA and were monitored clinically through the whole procedure. The patients also underwent bilateral NIRS monitoring during the surgery. During the monitoring period, we first clamped the external carotid artery (ECA), and after a 1 minute delay followed by clipping the internal carotid artery (ICA). The decrease in the cerebral oximetry values was analyzed separately after selective ICA clipping (ÚstÍ Selective Internal carotid artery Clamping “USIC” protocol). The decision to use a shunt was based solely on clinical symptomatology but the NIRS data were recorded and analyzed. All patients underwent DWI before and after CEA. RESULTS: One hundred and six patients (85%) underwent CEA without clinical deterioration while 19 patients (15%) clinically deteriorated during surgery. The mean drop in the cerebral oximetry after selective ICA clamping in clinically stable patients was 6% while in patients with clinical deterioration the NIRS decreased by 15% (p &lt; 0.05). When we set the cut-off value for selective shunting as a 10% decrease of the ipsilateral cerebral oximetry after selective ICA clamping, the sensitivity of the technique was 100% and the specificity 83%. CONCLUSIONS: Our study showed that a 10% decrease in the ipsilateral brain tissue oximetry after selective cross-clamping the ICA provides a reliable cut-off for selective shunting during CEA. More, bilateral NIRS monitoring allows differentiation between systemic or local events leading to brain hypoxia.

Cerebral oxymetry in patients with ischemic stroke and concomitant obstructive sleep apnea syndrome

Cerebral stroke is an important medical and social problem of our time and the most common cause of permanent disability. In patients with brain damage due to ischemic stroke and concomitant obstructive sleep apnoea, numerous episodes of hypoventilation and apnoea cause significant «failures» in saturation and changes in cerebral perfusion, which negatively affects immediate and long-term treatment outcomes. Cerebral oximetry is widely used in clinical practice in various fields of surgery (cardiovascular, paediatric, neurosurgery, etc.), but its potential as a method of monitoring secondary brain damage and controlling treatment in patients with ischaemic cerebral stroke is poorly understood. Objective — to evaluate the effect of non-invasive CPAP support (Continuous Positive Airway Pressure — a method of non-invasive respiratory support in which positive pressure is created in the patient’s airways) on cerebral oximetry in the treatment of patients with ischaemic stroke and concomitant obstructive sleep apnoea syndrome. Materials and methods. Patients with verified mild to moderate ischaemic stroke underwent screening diagnostics to confirm the presence of obstructive sleep apnoea syndrome (SomnoChek micro, Weinman, Germany). We studied 60 patients with obstructive sleep apnoea in the setting of ischemic stroke, who were divided into two groups depending on the treatment method: control (n = 30), in which only conventional stroke treatment was used, and experimental (n = 30), in which the traditional treatment regimen and respiratory support (auto-SAPP) during night sleep with the ResMed Air Sencei apparatus (Australia) were used. To monitor the effectiveness of respiratory support, along with other methods of objective control, cerebral oximetry was used using the Masimo Root apparatus (Masimo, USA). The average rSO2 values on the side of the stroke-affected hemisphere were recorded at the following times: at the beginning of the study, on the 3rd, 5th and 7th day of treatment. The data obtained were processed statistically. Results. The initial average values of rSO2 of the affected by stroke hemisphere in patients of groups I and II were in the range of pathological values, and were (49.27 ± 4.98) and (50.60 ± 5.40) %, respectively, that is, the groups at the beginning of the study were compared to each other. It was found, that in group I patients statistically significant changes in rSO2 % in the intervals of the 1st and 3rd days, the 3rd and 5th days, and the 5th and 7th days — were not observed. Only during the 7th day of observation we’ve recorded statistically significant rSO2 growth at 15.6 % compared to the initial values up to the mark of (57.03 ± 7.01) %. Instead, the rSO2 changes in patients of group II (who were performed СРАР-support at night against the traditional treatment of a stroke), were dynamic and statistically probable: a controlled index during the 3rd day of observation has increased at 12.2 %, during the 5th day — at 26.5 %, during the 7th day — at 33.6 % compared to the initial values up to the level of (67.64 ± 3.02) % compared to the initial values. Conclusions. Standardized medicinal therapy and early rehabilitation of patients with ischemic stroke does not affect the course and severity of concomitant obstructive sleep apnea syndrome and requires a supplement with the methods of non-invasive respiratory support during night sleep. Patients with ischemic stroke against the background of autoCPAP-therapy, were recorded positive dynamics in terms of correction of obstructive sleep apnea syndrome and stable normalization of cerebral oxymetry.

Cerebral Autoregulation Assessment through Near-Infrared Spectroscopy and Arterial Monitoring: Advancements and Clinical Implications

Cerebral autoregulation, maintaining stable cerebral blood flow across varying arterial pressures, is vital in-patient care during surgery. Traditional views suggest a mean arterial pressure range of 50-150 mm Hg for effective autoregulation. However, patient-specific variations in autoregulatory patterns, particularly in cases of impaired autoregulation, call for personalized hemodynamic and blood pressure management during surgical procedures. In the evaluation of cerebral autoregulation, NIRS serves as a beneficial monitoring tool. The cerebral oximetry index, correlating cerebral oxygen saturation with perfusion pressure, aids in determining autoregulation limits. The literature shows varying impacts of vasoactive drugs on patients with different autoregulatory responses, emphasizing the need for individualized care. In summary, NIRS is crucial for monitoring cerebral autoregulation, and adjusting arterial blood pressure targets based on NIRS data could improve prevention of cerebral hyper/hypoperfusion. This approach, moving away from a generalized strategy, advocates for a more customized, physiology-based patient management.

Reference Ranges for Regional Cerebral Oxygen Saturation with Masimo O3 after Birth and Differences with Other Devices.

Cerebral oximetry using near-infrared spectroscopy (NIRS) is a noninvasive optical technology widely used in neonatology. The present study aimed to define reference ranges for cerebral tissue oxygen saturation (crSO2) with a new four-wavelength NIRS device, Masimo O3 oximeter, during immediate transition after birth and compare values with those obtained previously with NIRO 200NX®. This was a prospective observational study using Masimo O3 device to measure crSO2 and regional cerebral fractional tissue oxygen extraction (cFTOE) in healthy term newborns delivered by primary cesarean section, during the 15 minutes after cord clamping. The neonates who required any medical support were excluded. The NIRS sensor was placed on the right forehead. Peripheral oxygen saturation and heart rate were continuously measured by pulse oximetry. Previous studies which established centiles for crSO2 with NIRO 200NX were used for comparison. A total of 44 newborns were included. The median crSO2 and cFTOE (interquartile range) at 2, 5, and 7 minutes was 54% (49-54), 71% (64-86), and 79% (73-84) and 0,25 (0,18-0,33), 0,19 (0,15-0,23), and 0,16 (0,12-0,21), respectively, with no further changes afterwards. The crSO2 measurements were significantly higher with Masimo O3 compared with NIRO-200NX. The present observational study presented reference ranges for crSO2 and cFTOE measured with Masimo O3 oximeter during the immediate neonatal transition. Values obtained with O3 were higher than those obtained with other oximeters. For this reason, crSO2 is device-specific so there must be known reference values for each oximeter to define therapeutic interventions based on crSO2 and assess cerebral oxygenation in clinical studies. · Masimo O3 uses four wavelengths to measure regional oxygen saturation value.. · O3 values of crSO2 and cFTOE differ with other neonatal oximeters at birth.. · Knowledge of reference range of O3 at birth is essential to guide resuscitation..

Comparison of the effects of dexmedetomidine and nitroglycerin on cerebral oxygen saturation using near-infrared spectroscopy in patients undergoing controlled hypotensive anaesthesia: A randomised controlled non-inferiority trial.

There is limited literature wherein the hypotensive drugs have been compared to know the cerebral effects by monitoring regional cerebral oxygen saturation (rScO2). This study aimed to compare the effects of dexmedetomidine and nitroglycerin on rScO2 during controlled hypotensive anaesthesia using near-infrared spectroscopy (NIRS). The primary objective was to evaluate the non-inferiority of dexmedetomidine versus nitroglycerin in the occurrence of cerebral desaturation events (CDEs) during hypotensive anaesthesia. Adult patients scheduled to undergo head and neck surgery under general anaesthesia randomised to receive either dexmedetomidine or nitroglycerin infusion for controlled hypotensive anaesthesia. Cerebral oximetry was monitored with NIRS, and data regarding CDEs, bilateral rScO2, and peri-operative haemodynamics were collected. Continuous data were analysed using unpaired Student's t-tests except for intra-group analyses, which were analysed using paired t-tests. Categorical data were analysed using the Chi-square test. For comparison of time to CDEs, Kaplan-Meier survival analysis with log-rank test was performed. Of the 82 patients in both groups, CDEs were observed in 15 patients each. A decrease from baseline by 20% was observed in three patients: one in Group N and two in Group D. Statistically, there was an equal risk of getting CDEs in the groups. The time to CDE was comparable (P > 0.05). The difference in heart rate was statistically significant (P < 0.001). Dexmedetomidine is non-inferior to nitroglycerin in terms of the occurrence of cerebral desaturation events when used for controlled hypotensive anaesthesia in head and neck surgeries.

Continuous Monitoring of Cerebral Autoregulation in Adults Supported by Extracorporeal Membrane Oxygenation.

Impaired cerebral autoregulation (CA) is one of several proposed mechanisms of acute brain injury in patients supported by extracorporeal membrane oxygenation (ECMO). The primary aim of this study was to determine the feasibility of continuous CA monitoring in adult ECMO patients. Our secondary aims were to describe changes in cerebral oximetry index (COx) and other metrics of CA over time and in relation to functional neurologic outcomes. This is a single-center prospective observational study. We measured COx, a surrogate measurement of cerebral blood flow measured by near-infrared spectroscopy, which is an index of CA derived from the moving correlation between mean arterial pressure (MAP) and slow waves of regional cerebral oxygen saturation. A COx value that approaches 1 indicates impaired CA. Using COx, we determined the optimal MAP (MAPOPT) and lower and upper limits of autoregulation for individual patients. These measurements were examined in relation to modified Rankin Scale (mRS) scores. Fifteen patients (median age 57years [interquartile range 47-69]) with 150 autoregulation measurements were included for analysis. Eleven were on veno-arterial ECMO (VA-ECMO), and four were on veno-venous ECMO (VV-ECMO). Mean COx was higher on postcannulation day 1 than on day 2 (0.2 vs. 0.09, p < 0.01), indicating improved CA over time. COx was higher in VA-ECMO patients than in VV-ECMO patients (0.12 vs. 0.06, p = 0.04). Median MAPOPT for the entire cohort was highly variable, ranging from 55 to 110mm Hg. Patients with mRS scores 0-3 (good outcome) at 3 and 6months spent less time outside MAPOPT compared with patients with mRS scores 4-6 (poor outcome) (74% vs. 82%, p = 0.01). The percentage of time when observed MAP was outside the limits of autoregulation was higher on postcannulation day 1 than on day 2 (18.2% vs. 3.3%, p < 0.01). In ECMO patients, it is feasible to monitor CA continuously at the bedside. CA improved over time, most significantly between postcannulation days 1 and 2. CA was more impaired in VA-ECMO patients than in VV-ECMO patients. Spending less time outside MAPOPT may be associated with achieving a good neurologic outcome.

Cerebral oxygenation saturation in childhood: difference by age and comparison of two cerebral oximetry algorithms.

Few reports are available on the monitoring of regional cerebral oxygen saturation (rSO2) in pediatric patients undergoing non-cardiac surgical procedures. In addition, no study has examined the rSO2 levels in children of a broad age range. In this study, we aimed to assess and compare rSO2 levels in pediatric patients of different age groups undergoing non-cardiac surgery. We used two oximeters, tNIRS-1, which uses time-resolved spectroscopy, and conventional INVOS 5100C. Seventy-eight children-26 infants, 26 toddlers, and 26 schoolchildren-undergoing non-cardiac surgery were included. We investigated the differences in the rSO2 levels among the age groups and the correlation between the models and physiological factors influencing the rSO2 values. rSO2 measured by INVOS 5100C was significantly lower in infants than those in other patients. rSO2 measured by tNIRS-1 was higher in the toddler group than those in the other groups. The rSO2 values of tNIRS-1 and INVOS 5100C were moderately correlated (r = 0.41); however, those of INVOS 5100C were approximately 20% higher, and a ceiling effect was observed. The values in INVOS 5100C and tNIRS-1 were affected by blood pressure and the minimum alveolar concentration of sevoflurane, respectively. In pediatric patients undergoing non-cardiac surgery, rSO2 values differed across the three age groups, and the pattern of these differences varied between the two oximeters employing different algorithms. Further research must be conducted to clarify cerebral oxygenation in children.

Machine learning-based prediction of cerebral oxygen saturation based on multi-modal cerebral oximetry data.

This study develops machine learning-based algorithms that facilitate accurate prediction of cerebral oxygen saturation using waveform data in the near-infrared range from a multi-modal oxygen saturation sensor. Data were obtained from 150,000 observations of a popular cerebral oximeter, Masimo O3™ regional oximetry (Co., United States) and a multi-modal cerebral oximeter, Votem (Inc., Korea). Among these observations, 112,500 (75%) and 37,500 (25%) were used for training and test sets, respectively. The dependent variable was the cerebral oxygen saturation value from the Masimo O3™ (0-100%). The independent variables were the time of measurement (0-300,000 ms) and the 16-bit decimal amplitudes values (infrared and red) from Votem (0-65,535). For the right part of the forehead, the root mean square error of the random forest (0.06) was much smaller than those of linear regression (1.22) and the artificial neural network with one, two or three hidden layers (2.58). The result was similar for the left part of forehead, that is, random forest (0.05) vs logistic regression (1.22) and the artificial neural network with one, two or three hidden layers (2.97). Machine learning aids in accurately predicting of cerebral oxygen saturation, employing the data from a multi-modal cerebral oximeter.

Effects of Pulsatile and Non-Pulsatile Cardiopulmonary Bypass Techniques in Coronary Artery Bypass Grafting Surgeries on Cerebral Perfusion.

We aimed to evaluate the effects of cardiopulmonary bypass (CPB) machines used in coronary artery bypass grafting surgeries on cerebral perfusion by performing cerebral oximetry monitoring [near-infrared spectroscopy (NIRS)], S100-β protein measurements, and neurocognitive function assessment tests using both pulsatile and non-pulsatile modes. A total of 44 patients, 22 non-pulsatile (Group NP) and 22 pulsatile (Group P), were included in the study. Hemodynamic parameters, arterial blood gas values, NIRS values and blood S100β protein levels were analyzed at five points: pre-induction (T1), initiation of CPB (T2), termination of CPB (T3), end of surgery (T4), and postoperative 24 h (T5). Two different neuropsychological tests were administered to patients in the preoperative and postoperative periods. There were no significant differences between the groups for demographic characteristics such as age, gender, body mass index, aortic cross-clamping, CPB, and operation durations. The mean arterial blood pressure and PaO2 values for the T2 measurements were significantly higher in group NP (P < 0.05). Regional cerebral oxygen saturation (rSO2) (NIRS) values at T3 and T4 were significantly higher in group P (P < 0.05). Serum S100β measurement values at T3 and T5 were significantly higher in group NP than in group P (P < 0.05). Serum S100β protein levels at T3 correlate with rSO2 results. There was no statistically significant difference between the two groups in terms of pH, lactate, glucose, partial pressure of carbon dioxide, and peripheral oxygen saturation values. Despite no difference between the two groups for neurocognitive function tests, we believe that pulsatile perfusion may be more beneficial for cerebral perfusion when S100β protein and NIRS values are considered. Further clinical studies are needed to evaluate the benefits of the pulsatile technique for cerebral perfusion.