Cerebral Oximetry Research Articles

Early Detection and Correction of Cerebral Desaturation With Noninvasive Oxy-Hemoglobin, Deoxy-Hemoglobin, and Total Hemoglobin in Cardiac Surgery: A Case Series.

Regional cerebral oxygen saturation (rS o2 ) obtained from near-infrared spectroscopy (NIRS) provides valuable information during cardiac surgery. The rS o2 is calculated from the proportion of oxygenated to total hemoglobin in the cerebral vasculature. Root O3 cerebral oximetry (Masimo) allows for individual identification of changes in total (ΔcHbi), oxygenated (Δ o2 Hbi), and deoxygenated (ΔHHbi) hemoglobin spectral absorptions. Variations in these parameters from baseline help identify the underlying mechanisms of cerebral desaturation. This case series represents the first preliminary description of Δ o2 Hbi, ΔHHbi, and ΔcHbi variations in 10 cardiac surgical settings. Hemoglobin spectral absorption changes can be classified according to 3 distinct variations of cerebral desaturation. Reduced cerebral oxygen content or increased cerebral metabolism without major blood flow changes is reflected by decreased Δ o2 Hbi, unchanged ΔcHbi, and increased ΔHHbi Reduced cerebral arterial blood flow is suggested by decreased Δ o2 Hbi and ΔcHbi, with variable ΔHHbi. Finally, acute cerebral congestion may be suspected with increased ΔHHbi and ΔcHbi with unchanged Δ o2 Hbi. Cerebral desaturation can also result from mixed mechanisms reflected by variable combination of those 3 patterns. Normal cerebral saturation can occur, where reduced cerebral oxygen content such as anemia is balanced by a reduction in cerebral oxygen consumption such as during hypothermia. A summative algorithm using rS o2 , Δ o2 Hbi, ΔHHbi, and ΔcHbi is proposed. Further explorations involving more patients should be performed to establish the potential role and limitations of monitoring hemoglobin spectral absorption signals.

Association of Cerebral and Systemic Physiology With Quantitative Electroencephalographic Characteristics of Early Posttraumatic Seizures.

Early posttraumatic seizures (EPTS) occur after pediatric traumatic brain injury and have been associated with unfavorable outcomes. We aimed to characterize the relationship among quantitative EEG characteristics of early posttraumatic seizures, cerebral and somatic physiologic measures. Differences in baseline physiologic, neuroimaging, and demographic characteristics between those with and without early posttraumatic seizures were investigated using Mann-Whitney U test or Fisher exact test. Multivariable dynamic structural equations modeling was used to investigate time series associations between ictal quantitative EEG characteristics with intracranial pressure, arterial blood pressure, heart rate (HR), and cerebral regional oximetry. Quantitative EEG characteristics included amplitude, total power, spectral edge frequency, peak value frequency, complexity, and periodicity. Among 72 children, 146 seizures were identified from 19 patients. Early posttraumatic seizures were associated with younger age ( P = 0.0034), increased HR ( P = 0.0018), and increased Glasgow Outcome Scale-Extended scores ( P = 0.0377). Group dynamic structural equations modeling analysis of the first seizure for patients demonstrated that intracranial pressure is negatively associated with spectral edge frequency (standardized regression coefficient -0.12, 99% credible interval [-0.21 to -0.04]), and HR is positively associated with peak value frequency (standardized regression coefficient 0.16, [0.00-0.31]). Among nine patients with seizures arising over the frontal lobe regions, HR was positively associated with peak value frequency (standardized regression coefficient 0.26 [0.02-0.50]) and complexity (standardized regression coefficient 0.14 [0.03-0.26]). Variation in strength and direction of associations was observed between subjects for relationships that were significant during group analysis. Quantitative EEG characteristics of pediatric early posttraumatic seizures are associated with variable changes in cerebral and systemic physiology, with spectral edge frequency negatively associated with intracranial pressure and peak value frequency positively associated with HR.

Real-Time Evaluation of Cerebral Autoregulation Based on Near-Infrared Spectroscopy to Predict Clinical Outcome after Bypass Surgery in Moyamoya Disease.

Impaired cerebral autoregulation (CA) can cause negative outcomes in neurological conditions. Real-time CA monitoring can predict and thereby help prevent postoperative complications for neurosurgery patients, especially those suffering from moyamoya disease (MMD). We applied the concept of moving average to the correlation between mean arterial blood pressure (MBP) and cerebral oxygen saturation (SCO2) to monitor CA in real time, revealing optimal window size for the moving average. The experiment was conducted with 68 surgical vital-sign records containing MBP and SCO2. To evaluate CA, the cerebral oximetry index (COx) and coherence obtained from transfer function analysis (TFA) were calculated and compared between patients with postoperative infarction and those who without. For real-time monitoring, the moving average was applied to COx and coherence to determine the differences between groups, and the optimal moving-average window size was identified. The average COx and coherence within the very-low-frequency (VLF) range (0.02-0.07 Hz) during the entire surgery were significantly different between the groups (COx: AUROC = 0.78, p = 0.003; coherence: AUROC = 0.69, p = 0.029). For the case of real-time monitoring, COx showed a reasonable performance (AUROC > 0.74) with moving-average window sizes larger than 30 minutes. Coherence showed an AUROC > 0.7 for time windows of up to 60 minutes; however, for windows larger than this threshold, the performance became unstable. With an appropriate window size, COx showed stable performance as a predictor of postoperative infarction in MMD patients.

Optimal bispectral index level of sedation and cerebral oximetry in traumatic brain injury: a non-invasive individualized approach in critical care?

BackgroundImpaired cerebral autoregulation has been linked with worse outcomes, with literature suggesting that current therapy guidelines fail to significantly impact cerebrovascular reactivity. The cerebral oximetry index (COx_a) is a surrogate measure of cerebrovascular reactivity which can in theory be obtained non-invasively using regional brain tissue oxygen saturation and arterial blood pressure. The goal of this study was to assess the relationship between objectively measured depth of sedation through BIS and autoregulatory capacity measured through COx_a.MethodsIn a prospectively maintained observational study, we collected continuous regional brain tissue oxygen saturation, intracranial pressure, arterial blood pressure and BIS in traumatic brain injury patients. COx_a was obtained using the Pearson’s correlation between regional brain tissue oxygen saturation and arterial blood pressure and ranges from − 1 to 1 with higher values indicating impairment of cerebrovascular reactivity. Using BIS values and COx_a, a curve-fitting method was applied to determine the minimum value for the COx_a. The associated BIS value with the minimum COx_a is called BISopt. This BISopt was both visually and algorithmically determined, which were compared and assessed over the whole dataset.ResultsOf the 42 patients, we observed that most had a parabolic relationship between BIS and COx_a. This suggests a potential “optimal” depth of sedation where COx_a is the most intact. Furthermore, when comparing the BISopt algorithm with visual inspection of BISopt, we obtained similar results. Finally, BISopt % yield (determined algorithmically) appeared to be independent from any individual sedative or vasopressor agent, and there was agreement between BISopt found with COx_a and the pressure reactivity index (another surrogate for cerebrovascular reactivity).ConclusionsThis study suggests that COx_a is capable of detecting disruption in cerebrovascular reactivity which occurs with over-/under-sedation, utilizing a non-invasive measure of determination and assessment. This technique may carry implications for tailoring sedation in patients, focusing on individualized neuroprotection.

The Relationship between Cerebrovascular Reactivity and Cerebral Oxygenation during Hemodialysis.

Patients with kidney failure treated with hemodialysis (HD) may be at risk for cerebral hypoperfusion due to HD-induced BP decline in the setting of impaired cerebral autoregulation. Cerebrovascular reactivity (CVR), the cerebrovascular response to vasoactive stimuli, may be a useful indicator of cerebral autoregulation in the HD population and identify those at risk for cerebral hypoperfusion. We hypothesize that CVR combined with intradialytic BP changes will be associated with declines in cerebral oxygenation saturation (ScO2) during HD. Participants completed the MRI scans on a non-HD day and cerebral oximetry during HD. We measured CVR with resting-state fMRI (rs-fMRI) without a gas challenge and ScO2 saturation with near-infrared spectroscopy. Regression analysis was used to examine the relationship between intradialytic cerebral oxygen desaturation, intradialytic BP, and CVR in different gray matter regions. Twenty-six patients on HD had complete data for analysis. Sixteen patients were men, 18 had diabetes, and 20 had hypertension. Mean±SD age was 65.3±7.2 years, and mean±SD duration on HD was 11.5±9.4 months. CVR in the anterior cingulate gyrus (ACG; P=0.03, r2 =0.19) and insular cortex (IC; P=0.03, r2 =0.19) regions negatively correlated with decline in intradialytic ScO2. Model prediction of intradialytic ScO2 improved when including intradialytic BP change and ultrafiltration rate to the ACG rsCVR (P<0.01, r2 =0.48) and IC rsCVR (P=0.02, r2 =0.35) models, respectively. We found significant relationships between regional rsCVR measured in the brain and decline in intradialytic ScO2. Our results warrant further exploration of using CVR in determining a patient's risk of cerebral ischemic injury during HD.

The Influence of Age on Cerebral Tissue Oxygenation in Vasovagal Syncope and Orthostatic Hypotension.

Age-related physiological impairment increases susceptibility to syncope. We tested the hypotheses that cerebral oxygenation during orthostatic provocation, as well as the level at which syncope occurs, differs according to age. Non-invasive hemodynamic monitoring and cerebral oximetry were applied during a head-up tilt test in 139 patients with vasovagal syncope (mean (SD) 45, (17) years, 60%-female); 121 patients with orthostatic hypotension (61.4 (19.2) years, 49.6%-female); and 82 patients with a negative head-up tilt test (45 (18) years, 61%-female). Group differences in cerebral tissue oxygenation levels and systolic blood pressure were assessed in supine at 3 and 10 min of orthostatic provocation, 30 s before (i.e., presyncopal phase) and during syncope in age groups of <30, 30–60, and >60 years. During the head-up tilt test, cerebral tissue oxygenation at the presyncopal phase decreased with age, both in patients with vasovagal syncope (<30 years: 66.9 ± 6.2, 30–60: 64.5 ± 6.1, >60: 62.2 ± 5.8%; p = 0.009) and orthostatic hypotension (<30: 67.4 ± 4.4, 30–60: 61.6 ± 6.2, >60: 57.5 ± 3.9; p < 0.001). Mean systolic blood pressure at the presyncopal phase did not differ according to age. Cerebral oxygenation prior to syncope in older individuals with vasovagal syncope and orthostatic hypotension is lower compared with younger individuals independently of systolic blood pressure. This suggests that the level of cerebral oxygenation at which syncope is elected is lower in older individuals.

Safe Inspiratory Pressures Threshold in Lung Recruitment Maneuvers: An In Vivo Neonatal ARDS Model.

The aim of this study was to define the level of peak inspiratory pressure (PIP) and mean airway pressure ([Formula: see text]) at which a pneumothorax is produced in an in vivo ARDS neonate model. In addition, we analyzed the hemodynamic response and cerebral parameters during the progressive increase of intrathoracic pressure. We designed a prospective, experimental study with 11 Landrace × Large White pigs < 48 h from their birth. With the pigs under general anesthesia, tracheal intubation, invasive hemodynamic monitoring with a pediatric arterial thermodilution catheter, intracranial pressure, cerebral oximetry through near-infrared spectroscopy, and bilateral chest tube catheterization were performed. The ARDS model was developed with bronchoalveolar lavages. The rise in inspiratory pressure was performed achieved by increasing PEEP in stepwise increments at a constant driving pressure. PEEP was increased 5 cm H2O every 2 min until a pneumothorax was observed. A descriptive analysis, a Kaplan-Meier curve, and a regression analysis by using a generalized estimation equation were performed. A pneumothorax was observed in a median (interquartile range [IQR]) [Formula: see text] of 54 (46-56) cm H2O and median (IQR) PIP of 65 (58-73) cm H2O; asystole at median (IQR) [Formula: see text] of 49 (36-54) cm H2O and median (IQR) PIP of 60 (48-65) cm H2O. Hemodynamic changes in the median artery pressure, cardiac output, and myocardial contractility were observed above the range of [Formula: see text] of 14 cm H2O (PIP 25 and PEEP 10 cm H2O). Disturbances in intracranial pressure and cerebral oximetry through near-infrared spectroscopy appeared when deep hypotension and asystole occurred. A progressive increase of PEEP at a constant driving pressure did not increase severe adverse events at the range of pressures that we routinely use in neonates with ARDS. Asystole, pneumothorax, and cerebral compromise appeared at high intrathoracic ranges of pressure. Hemodynamics must be strictly monitored in all patients during the performance of lung recruitment maneuvers because hemodynamic deflections emerge early, at a range of pressures commonly used in ventilated neonates with ARDS.

Role of Cerebral Oximetry in Extracorporeal Membrane Oxygenation

AbstractCerebral oximetry, which is based on near-infrared spectroscopy (NIRS) technology, is an optical technique that allows for noninvasive and continuous monitoring of brain oxygenation by determining cerebral tissue blood oxygen saturation. Many research and observational studies were performed with neonates using various types of NIRS/cerebral oximetry monitors. However, no food and drug administration (FDA) approved-cerebral oximeter is available for neonates. Successful validation of cerebral oximetry for the FDA has been done in human adult volunteer studies under protocols in which jugular bulb and arterial blood samples were obtained under different levels of fractional inspired oxygen levels.

Early Changes in Near-Infrared Spectroscopy Are Associated With Cardiac Arrest in Children With Congenital Heart Disease.

BackgroundThe association of near-infrared spectroscopy (NIRS) with various outcomes after pediatric cardiac surgery has been studied extensively. However, the role of NIRS in the prediction of cardiac arrest (CA) in children with heart disease has yet to be evaluated. We sought to determine if a model utilizing regional cerebral oximetry (rSO2c) and somatic oximetry (rSO2s) could predict CA in children admitted to a single-center pediatric cardiac intensive care unit (CICU).MethodsWe retrospectively reviewed 160 index CA events for patients admitted to our pediatric CICU between November 2010 and January 2019. We selected 711 control patients who did not have a cardiac arrest. Hourly data was collected from the electronic health record (EHR). We previously created a machine-learning algorithm to predict the risk of CA using EHR data. Univariable analysis was done on these variables, which we then used to create a multivariable logistic regression model. The outputs from the model were presented by odds ratio (OR) and 95% confidence interval (CI).ResultsWe created a multivariable model to evaluate the association of CA using five variables: arterial saturation (SpO2)- rSO2c difference, SpO2-rSO2s difference, heart rate, diastolic blood pressure, and vasoactive inotrope score. While the SpO2-rSO2c difference was not a significant contributor to the multivariable model, the SpO2-rSO2s difference was. The average SpO2-rSO2s difference cutoff with the best prognostic accuracy for CA was 29% [CI 26–31%]. In the multivariable model, a 10% increase in the SpO2-rSO2s difference was independently associated with increased odds of CA [OR 1.40 (1.18, 1.67), P < 0.001] at 1 h before CA. Our model predicted CA with an AUROC of 0.83 at 1 h before CA.ConclusionIn this single-center case-control study of children admitted to a pediatric CICU, we created a multivariable model utilizing hourly data from the EHR to predict CA. At 1 h before the event, for every 10% increase in the SpO2-rSO2s difference, the odds of cardiac arrest increased by 40%. These findings are important as the field explores ways to capitalize on the wealth of data at our disposal to improve patient care.

Exploring Trends in Neuromonitoring Use in a General Pediatric ICU: The Need for Standardized Guidance.

Neuromonitoring has become more standardized in adult neurocritical care, but the utility of different neuromonitoring modalities in children remains debated. We aimed to describe the use of neuromonitoring in critically ill children with and without primary neurological diseases. We conducted a retrospective review of patients admitted to a 32-bed, non-cardiac PICU during a 12-month period. Neuro-imaging, electroencephalogram (EEG), cerebral oximetry (NIRS), automated pupillometry, transcranial doppler (TCD), intracranial pressure (ICP) monitoring, brain tissue oxygenation (PbtO2), primary diagnosis, and outcome were extracted. Neuromonitoring use by primary diagnosis and associations with outcome were observed. Of 1946 patients, 420 received neuro-imaging or neuromonitoring. Primary non-neurological diagnoses most frequently receiving neuromonitoring were respiratory, hematologic/oncologic, gastrointestinal/liver, and infectious/inflammatory. The most frequently used technologies among non-neurological diagnoses were neuro-imaging, EEG, pupillometry, and NIRS. In the multivariate analysis, pupillometry use was associated with mortality, and EEG, NIRS, and neuro-imaging use were associated with disability. Frequencies of TCD and PbtO2 use were too small for analysis. Neuromonitoring is prevalent among various diagnoses in the PICU, without clear benefit on outcomes when used in an ad hoc fashion. We need standard guidance around who, when, and how neuromonitoring should be applied to improve the care of critically ill children.

Influence of the Trendelenburg position and carboxyperitoneum on cerebral tissue oximetry values

Background. Cerebral tissue oximetry (rSO2) can be used to assess cerebral circulation. Cerebral tissue oximetry studies have been performed in the Trendelenburg position (30º), but data for 45 o are not available.Objective. To study the effect of the Trendelenburg position (45°) under carboxyperitoneum conditions on rSO2 and hemodynamic parameters.Design and methods. A single-center, prospective, descriptive study was conducted among patients (n = 30) who underwent robot-assisted laparoscopic prostatectomy. We measured rSO2 on the left and right, central venous pressure (CVP), mean arterial pressure (MAP), venous saturation at points: T1 — after induction of anesthesia and start of measurements; T2 — 5 minutes after positioning the patient in the Trendelenburg position of 45o; T3 — 15 minutes; T4 — 30 minutes; T5 — after returning to a horizontal position. Cerebral perfusion was assessed using cerebral perfusion pressure (CPP).Results. rSO2 on the right and left at points T2, T3 and T5 significantly exceeded T1. There was a significant increase in BP mean at T2 and T3, as well as a significant increase in CVP at T2, T3 and T4 compared to T1. The CPP significantly decreased compared to T1 at points T3, T4 and T5.Conclusions. The Trendelenburg position with a tilt angle of 45º in combination with carboxyperitoneum is accompanied by an increase in rSO2, blood pressure and CVP.

Changes in Cerebral Oximetry in Patients Undergoing Shoulder Replacement Surgery

Abstract Degenerative joint diseases affect the elderly population, and advanced orthopaedic surgery offers novel solutions. The semi-sitting position is used during shoulder replacement surgery. There have been reports of transient and permanent neurological damage following surgery. We aimed to determine cerebral desaturation events (CDEs) during shoulder replacement surgery under general anaesthesia. This prospective, observational study was conducted at the Hospital of Traumatology and Orthopaedics. A cohort of 24 patients received combined plexus brachialis block and endotracheal anaesthesia. Their cerebral regional oxygen saturation index (rSO2) and mean arterial blood pressure (MAP) were recorded and compared in predefined intervals: before induction, post-induction, after getting in a sitting position, after cementing, and after extubation. Hypotension was defined as the occurrence of any of the following: either a &gt; 30% decline in MAP from the baseline or a MAP &lt; 65 mmHg. CDEs were defined as a 20% reduction in frontal lobe oxygenation. Calculations were made using SPSS software (Version 14.0.2, SPSS Inc.). There was a significant correlation between MAP and rSO2 after positioning, between MAP after intubation and rSO2., and between MAP before intubation and rSO2 at the end of surgery. One in three patients who experienced hypotension also experienced a CDE. rSO2 fluctuations correlated with MAP.

Comparison of different metrics of cerebral autoregulation in association with major morbidity and mortality after cardiac surgery

BackgroundCardiac surgery studies have established the clinical relevance of personalised arterial blood pressure management based on cerebral autoregulation. However, variabilities exist in autoregulation evaluation. We compared the association of several cerebral autoregulation metrics, calculated using different methods, with outcomes after cardiac surgery. MethodsAutoregulation was measured during cardiac surgery in 240 patients. Mean flow index and cerebral oximetry index were calculated as Pearson's correlations between mean arterial pressure (MAP) and transcranial Doppler blood flow velocity or near-infrared spectroscopy signals. The lower limit of autoregulation and optimal mean arterial pressure were identified using mean flow index and cerebral oximetry index. Regression models were used to examine associations of area under curve and duration of mean arterial pressure below thresholds with stroke, acute kidney injury (AKI), and major morbidity and mortality. ResultsBoth mean flow index and cerebral oximetry index identified the cerebral lower limit of autoregulation below which MAP was associated with a higher incidence of AKI and major morbidity and mortality. Based on magnitude and significance of the estimates in adjusted models, the area under curve of MAP < lower limit of autoregulation had the strongest association with AKI and major morbidity and mortality. The odds ratio for area under the curve of MAP < lower limit of autoregulation was 1.05 (95% confidence interval, 1.01–1.09), meaning every 1 mm Hg h increase of area under the curve was associated with an average increase in the odds of AKI by 5%. ConclusionsFor cardiac surgery patients, area under curve of MAP < lower limit of autoregulation using mean flow index or cerebral oximetry index had the strongest association with AKI and major morbidity and mortality. Trials are necessary to evaluate this target for MAP management.

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

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

Evaluation of the robustness of cerebral oximetry to variations in skin pigmentation using a tissue-simulating phantom.

Clinical studies have demonstrated that epidermal pigmentation level can affect cerebral oximetry measurements. To evaluate the robustness of these devices, we have developed a phantom-based test method that includes an epidermis-simulating layer with several melanin concentrations and a 3D-printed cerebrovascular module. Measurements were performed with neonatal, pediatric and adult sensors from two commercial oximeters, where neonatal probes had shorter source-detector separation distances. Referenced blood oxygenation levels ranged from 30 to 90%. Cerebral oximeter outputs exhibited a consistent decrease in saturation level with simulated melanin content; this effect was greatest at low saturation levels, producing a change of up to 15%. Dependence on pigmentation was strongest in a neonatal sensor, possibly due to its high reflectivity. Overall, our findings indicate that a modular channel-array phantom approach can provide a practical tool for assessing the impact of skin pigmentation on cerebral oximeter performance and that modifications to algorithms and/or instrumentation may be needed to mitigate pigmentation bias.

Cerebral Tissue Oxygen Saturation Is Enhanced in Patients following Transcatheter Aortic Valve Implantation: A Retrospective Study.

Transcatheter aortic valve implantation (TAVI) has emerged as an alternative to surgical aortic valve replacement. The aim of this study was to evaluate whether a relevant alteration in cerebral tissue oxygen saturation (rSO2) could be detected following TAVI. Retrospective data analysis included 275 patients undergoing TAVI between October 2016 and December 2020. Overall, rSO2 significantly increased following TAVI (64.6 ± 10% vs. 68.1 ± 10%, p < 0.01). However, a significant rise was only observed in patients with a preoperative rSO2 < 60%. Of the hemodynamic confounders studied, hemoglobin, mean arterial pressure and blood pH were lowered, while central venous pressure and arterial partial pressure of carbon dioxide (PaCO2) were slightly elevated (PaCO2: 39 (36–43) mmHg vs. 42 (37–47) mmHg, p = 0.03; pH: 7.41 (7.3–7.4) vs. 7.36 (7.3–7.4), p < 0.01). Multivariate linear regression modeling identified only hemoglobin as a predictor of altered rSO2. Patients with a EuroScore II above 4% and an extended ICU stay were found to have lower rSO2, while no difference was observed in patients with postoperative delirium or between the implanted valve types. Further prospective studies that eliminate differences in potential confounding variables are necessary to confirm the rise in rSO2. Future research should provide more information on the value of cerebral oximetry for identifying high-risk patients who will require further clinical interventions in the setting of the TAVI procedure.

Is low cerebral near infrared spectroscopy oximetry associated with neurodevelopment of preterm infants without brain injury?

To evaluate the association between low regional cerebral oxygen saturation (rScO2) and neurodevelopment in preterm infants classified as no brain injury (NBI). We retrospectively reviewed data of rScO2 monitoring during the first 3days of life of infants with a gestational age (GA)<28weeks or birth weight (BW)<1,000g, with and without brain injury (BI). BI was defined as intraventricular haemorrhage, cystic periventricular leukomalacia or cerebellar haemorrhage. Univariate and multivariate analyses were used to study the association of rScO2<55% for more than 10h in the first 3days of life (NIRS<55%>10H) and the 24months neurodevelopment. Of the 185 patients who met the inclusion criteria, 31% were classified as BI infants and 69% NBI. BI compared to NBI infants had a significantly lower GA and a higher incidence of complications of prematurity. Mean rScO2 in the first 72h of life was significantly lower in BI than NBI. NIRS<55%>10H in NBI patients was negatively associated with neurodevelopmental scores both at the univariate andmultivariate analysis (p<0.05). NBI infants with NIRS<55%>10H were found to have lower systemic oxygenation than their counterparts with rScO2<55% for less than 10h. NIRS<55%>10H in NBI small preterm infants was found to be an independent predictor of neurodevelopment at 24months and it was associated with low systemic saturation values.

Near-infrared spectroscopy during cardiopulmonary resuscitation for pediatric cardiac arrest: A prospective, observational study

AimCerebral oxygenation (rSO2) is not routinely measured during pediatric cardiopulmonary resuscitation (CPR). We aimed to determine whether higher intra-arrest rSO2 was associated with return of spontaneous circulation (ROSC) and survival to hospital discharge. MethodsProspective, single-center observational study of cerebral oximetry using near-infrared spectroscopy (NIRS) during pediatric cardiac arrest from 2016 to 2020. Eligible patients had ≥30 s of rSO2 data recorded during CPR. We compared median rSO2 and percentage of rSO2 measurements above a priori thresholds for the entire event and the final five minutes of the CPR event between patients with and without ROSC and survival to discharge. ResultsTwenty-one patients with 23 CPR events were analyzed. ROSC was achieved in 17/23 (73.9%) events and five/21 (23.8%) patients survived to discharge. The median rSO2 was higher for events with ROSC vs. no ROSC for the overall event (62% [56%, 70%] vs. 45% [35%, 51%], p = 0.025) and for the final 5 minutes of the event (66% [55%, 72%] vs. 43% [35%, 44%], p = 0.01). Patients with ROSC had a higher percentage of measurements above 50% during the final five minutes of CPR (100% [100%, 100%] vs. 0% [0%, 29%], p = 0.01). There was no association between rSO2 and survival to discharge. ConclusionsHigher cerebral rSO2 during CPR for pediatric cardiac arrest was associated with higher rates of ROSC but not with survival to discharge.

Carbon Dioxide Reactivity of Brain Tissue Oxygenation after Pediatric Traumatic Brain Injury.

Background: We investigated how changes in partial pressure of brain tissue oxygenation (PbtO2) relate to end-tidal carbon dioxide (EtCO2) after pediatric traumatic brain injury (TBI). Methods: Dynamic structural equation modeling (DSEM) was used to investigate associations between EtCO2 and PbtO2, with positive associations indicating intact CO2 reactivity of PbtO2, and negative associations indicating impaired reactivity. Sub-analyses were performed to investigate associations of PbtO2 to intracranial pressure (ICP), arterial blood pressure (ABP) and cerebral regional oximetry (rSO2). Results: Among 14 patients, a positive association between PbtO2 and EtCO2 was demonstrated (SRC 0.05, 95% CI [0.04, 0.06]), with 9 patients demonstrating intact CO2 reactivity and 5 patients demonstrating impaired reactivity. Patients demonstrating intact CO2 reactivity had positive associations between PbtO2 and ICP (0.22 [0.21, 0.23]), whereas patients with impaired reactivity had negative associations (−0.28 [−0.29, −0.28]). Patients demonstrating intact CO2 reactivity had negative associations between PbtO2 and rSO2 (−0.08 [−0.09, −0.08]), whereas patients with impaired reactivity had positive associations (−0.15 [0.14, 0.16]). Compared to patients with intact CO2 reactivity, those with impaired reactivity had increased ICP (p < 0.0000), lower PbtO2 (p < 0.0000) and higher PRx (p = 0.0134). Conclusion: After TBI, CO2 reactivity of PbtO2 can be heterogenous, necessitating further work investigating factors contributing toward impaired reactivity.

The Predictive Power of Near-Infrared Spectroscopy in Improving Cognitive Problems in Patients Undergoing Brain Surgeries: A Systematic Review.

One of the main objectives in neurosurgical procedures is the prevention of cerebral ischemia and hypoxia leading to secondary brain injury. Different methods for early detection of intraoperative cerebral ischemia and hypoxia have been used. Near-infrared spectroscopy (NIRS) is a simple, non-invasive method for monitoring cerebral oxygenation increasingly used today. The aim of this study was to systematically review the brain monitoring with NIRS in neurosurgery. The search process resulted in the detection of 324 articles using valid keywords on the electronic databases, including Embase, PubMed, Scopus, Web of Science, and Cochrane Library. Subsequently, the full texts of 34 studies were reviewed, and finally 11 articles (seven prospective studies, three retrospective studies, and one randomized controlled trial) published from 2005 to 2020 were identified as eligible for systematic review. Meta-analysis was not possible due to high heterogeneity in neurological and neurosurgical conditions of patients, expression of different clinical outcomes, and different standard reference tests in the studies reviewed. The results showed that NIRS is a non-invasive cerebral oximetry that provides continuous and measurable cerebral oxygenation information and can be used in a variety of clinical settings.