A Review of Monitoring Methods for Cerebral Blood Oxygen Saturation

Multimodal neuromonitoring in the nordic countries: experiences and attitudes - a multi-institutional survey

BACKGROUND

Multimodal neuromonitoring (MMM) aids early detection of secondary brain injury in neurointensive care and facilitates research in pathophysiologic mechanisms of the injured brain. Invasive ICP monitoring has been the gold standard for decades, however additional methods exist (aMMM). It was hypothesized that local practices regarding aMMM vary considerably and that inter-and intracenter consensus is low. The survey aimed to investigate this hypothesis including the knowledge, attitudes towards, and use of aMMM in the neurointensive care setting in the Nordic countries.

METHOD

The survey was distributed amongst 54 neurosurgical trainees at a Nordic neurosurgery training course and supplemented with 16 center-appointed neuromonitoring experts representing 16 of the 19 neurosurgical centers in the Nordic countries (Norway, Sweden, Denmark, and Finland).

RESULTS

The response rate was 100% amongst the training course attendents, as well as the center-appointed experts with a total of 70 respondents. The experts covered 16/19 Nordic centers. In-center disagreement was high concerning the use of aMMM methods. In patients with traumatic brain injury, subarachnoid hemorrhage, or other acute brain injuries 50% of the appointed experts stated transcranial Doppler ultrasound (TCD) to be used in most cases in their ICU, and an additional 25% for selected cases. Most appointed experts agreed on electroencephalography (EEG) for selected cases 63%, but only 19% for most cases. Routine use of Invasive brain tissue oxygenation (PbtO2) was stated by 25-63% and cerebral microdialysis (CMD) by 19-38%. The main perceived concerns with aMMM methods were the usefulness for outcome-changing interventions (43%) and financial issues (19%). Most respondents (67%) believed automated combined analysis of aMMM to be a likely future scenario.

CONCLUSION

There was a remarkable variation in the reported use of aMMM among Nordic neurosurgical centers, indicating an extensive lack of consensus on need and utility. Surprisingly routine use of TCD was stated by 75%, presumably for routine monitoring of SAH patients, whereas CMD was mostly considered a research tool. Interestingly, junior staff and appointed experts disagreed on intended local routines, indicating that application of aMMM was more governed organically and by case than on explicit guidelines or that uniform management was not prioritized.

Evidence-Based Approach to Cerebral Vasospasm and Delayed Cerebral Ischemia: Milrinone as a Therapeutic Option-A Narrative Literature Review and Algorithm Treatment Proposition

Aneurysmal subarachnoid hemorrhage (aSAH) is a severe neurocritical condition often complicated by cerebral vasospasm (CVS), leading to delayed cerebral ischemia (DCI) and significant morbidity and mortality. Despite advancements in management, therapeutic options with robust evidence remain limited. Milrinone, a phosphodiesterase type 3 (PDE3) inhibitor, has emerged as a potential therapeutic option. Intravenous milrinone demonstrated clinical and angiographic improvement in 67% of patients, reducing the need for mechanical angioplasty and the risk of functional disability at 6 months (mRS ≤ 2). Side effects, including hypotension, tachycardia, and electrolyte disturbances, were observed in 33% of patients, occasionally leading to early drug discontinuation. Based on the evidence, we propose a treatment algorithm for using milrinone to optimize outcomes and standardize its application in neurocritical care settings.

Development of hemoglobin microbubbles for acoustic blood oxygen sensing: A study on PEGylation and gas core modification for in vivo applications

The creation of innovative ultrasound contrast agents (UCAs) with the ability to monitor oxygen levels in real-time holds immense potential for advancing early diagnosis of various medical conditions such as hypoxic/reperfusion injury. In this study, we propose the development of oxygen sensitive UCAs using microbubbles composed of hemoglobin (HbMBs), which can function as sensors for blood oxygen levels. Previously, we performed a study highlighting the initial proof-of-concept efficacy of air-filled HbMBs in detecting oxygenation changes in vitro, offering a promising tool for clinically detecting tissue hypoxia. Nevertheless, a significant drawback of this approach is the potential for immune reactions and toxicity when hemoglobin is outside its natural red blood cell environment. Moreover, in vitro, HbMBs had low stability, with more than 90% decrease in their concentration after 120 minutes. Therefore, careful consideration of the surface properties and the gas core of HbMBs is crucial. Here, we formulated PEGylated HbMBs (PHbMBs), and investigated their stability, immunogenicity, and their acoustic response in oxygenated and deoxygenated media in vitro. We optimized PEGylated HbMBs (PHbMBs), showing a 42% reduction in immunogenicity and significantly improved stability in vitro, while maintaining their oxygen-binding and acoustic response. In vivo, PHbMBs demonstrated similar contrast enhancement to that of non-PEGylated MBs, demonstrating that PEGylation does not decrease HbMBs' acoustic signaling. Finally, changing the gas core from air to PFB increased PHbMBs' mean circulation time more than 11-fold, without diminishing their responsiveness to oxygen. Overall, the proposed oxygen sensitive PHbMBs offer a promising avenue for real-time acoustic detection of blood oxygen levels, paving the way for potential clinical applications in monitoring critically ill patients. STATEMENT OF SIGNIFICANCE: This research explores the emergent field of Acoustic Oxygen Imaging in vivo using hemoglobin-based microbubbles. This innovative contrast agent approach involves imaging using crosslinked biomaterial comprised of the hemoglobin protein, aiming to transform the way we monitor blood oxygen levels with ultrasound. This work fundamentally addresses central concerns of improving bubble stability and circulation life for eventual clinical use, while minimizing toxicity. Importantly, we demonstrate that PEGylation of hemoglobin microbubbles enhances their stability, reduces immunogenicity, and maintains acoustic responsiveness. The incorporation of perfluorobutane into the bubble core increases the longevity of these microbubbles in circulation, while sustaining their oxygen sensitivity. Favorable in vivo results highlight the potential of this technology in real-time acoustic detection of blood oxygen levels.

The Effects of Head Elevation on Intracranial Pressure, Cerebral Perfusion Pressure, and Cerebral Oxygenation Among Patients with Acute Brain Injury: A Systematic Review and Meta-Analysis

BACKGROUND

Head elevation is recommended as a tier zero measure to decrease high intracranial pressure (ICP) in neurocritical patients. However, its quantitative effects on cerebral perfusion pressure (CPP), jugular bulb oxygen saturation (SjvO2), brain tissue partial pressure of oxygen (PbtO2), and arteriovenous difference of oxygen (AVDO2) are uncertain. Our objective was to evaluate the effects of head elevation on ICP, CPP, SjvO2, PbtO2, and AVDO2 among patients with acute brain injury.

METHODS

We conducted a systematic review and meta-analysis on PubMed, Scopus, and Cochrane Library of studies comparing the effects of different degrees of head elevation on ICP, CPP, SjvO2, PbtO2, and AVDO2.

RESULTS

A total of 25 articles were included in the systematic review. Of these, 16 provided quantitative data regarding outcomes of interest and underwent meta-analyses. The mean ICP of patients with acute brain injury was lower in group with 30° of head elevation than in the supine position group (mean difference [MD] - 5.58 mm Hg; 95% confidence interval [CI] - 6.74 to - 4.41 mm Hg; p < 0.00001). The only comparison in which a greater degree of head elevation did not significantly reduce the ICP was 45° vs. 30°. The mean CPP remained similar between 30° of head elevation and supine position (MD - 2.48 mm Hg; 95% CI - 5.69 to 0.73 mm Hg; p = 0.13). Similar findings were observed in all other comparisons. The mean SjvO2 was similar between the 30° of head elevation and supine position groups (MD 0.32%; 95% CI - 1.67% to 2.32%; p = 0.75), as was the mean PbtO2 (MD - 1.50 mm Hg; 95% CI - 4.62 to 1.62 mm Hg; p = 0.36), and the mean AVDO2 (MD 0.06 µmol/L; 95% CI - 0.20 to 0.32 µmol/L; p = 0.65).The mean ICP of patients with traumatic brain injury was also lower with 30° of head elevation when compared to the supine position. There was no difference in the mean values of mean arterial pressure, CPP, SjvO2, and PbtO2 between these groups.

CONCLUSIONS

Increasing degrees of head elevation were associated, in general, with a lower ICP, whereas CPP and brain oxygenation parameters remained unchanged. The severe traumatic brain injury subanalysis found similar results.

Carotid artery stenting for symptomatic carotid near occlusions: Feasibility, safety and outcome analysis

INTRODUCTION

Extracranial internal carotid stenosis (EICS) is a well-established cause of stroke. Carotid near-occlusion (CNO), either distally collapsed or not, is a rare sub-type of EICS with conflicting data regarding the necessity for treatment. The aim of this study is to evaluate the results of carotid artery stenting (CAS) for patients with symptomatic CNOs.

MATERIAL AND METHODS

Institutional review board (I06-420-23) approval was obtained for this retrospective study. Consecutive data from January 2019 to January 2023 was obtained. Sixty-five patients underwent 66 procedures for symptomatic CNOs. Diagnosis of CNOs were made with DSA images. Treatment decisions were made by a multidisciplinary team. Patient data including age, gender, clinical presentation, affected side, complications (initial/ follow-up), and pre and post mRS scores were recorded and analyzed.

RESULTS

There were 22 female and 43 male patients with symptomatic CNOs (mean age: 71.52 ± 9.32 years). The mean time from symptom-to-treatment was 3.91 weeks ± 3.74 weeks (ranging from 0 to 20 weeks). There were eight events recorded in the 30 days period after CAS; five (7.7%) were cerebral hyperperfusion syndrome (one causing haemorrhage) and three (4.5%) ischemic complications. Permanent neurologic deficit rate was 6% and 61 patients (94%) mRS scores were unchanged during last follow-up. Mean follow-up period was 22.94 ± 16.67 months (ranging from 0.5 to 60 months).

CONCLUSION

Our study demonstrated that in the complex population of patients with symptomatic CNOs, CAS is a feasible option with acceptable rate of permanent neurologic deficits. Further studies are needed to assess its safety and long-term efficacy.

Effect of nursing care based on goal-oriented mind mapping model on the prognosis of patients with severe brain injury

The objective of this study was to observe the effect of nursing care based on goal-oriented mind-mapping on the prognosis of patients with severe brain injury. Clinical data of 116 patients with severe brain injury admitted to Qinghe County Central Hospital between March 2021 and August 2023 were retrospectively analyzed. Based on the nursing mode the patients received, they were divided into an Observation group (n = 58, patients received nursing based on the goal-oriented mind mapping mode) and a Control group (n = 58, patients received routine care). Data on length of hospital stay, complications, functional recovery, cerebral oxygen metabolism, and quality of life scores of the 2 groups were collected and analyzed. The length of hospital stay of the Observation group was shorter than that of the Control group (P < .05). The total incidence of complications in the Observation group was lower than that in the Control group (P < .05). After intervention, neurological function, cerebral oxygen metabolism indicators, and quality of life of the 2 groups improved significantly compared with those before the intervention; furthermore, the neurological function and cerebral oxygen metabolism indexes of the Observation group were better than those of the Control group (P < .05). The nursing care based on goal-oriented mind-mapping model for patients with severe brain injury can effectively shorten the length of hospital stay, reduce the occurrence of prognostic complications, and improve the recovery of neurological and limb motor functions, and ultimately achieve the goal of improving the quality of life.

Extracorporeal Off-Pump Antegrade Cerebral Perfusion in Reconstructive Surgery for Type A Aortic Dissection With Cerebral Malperfusion

Introduction Type A aortic dissection (TAAD) is a life-threatening condition that often leads to cerebral malperfusion (CM), a severe complication that can result in permanent neurological damage. Traditionally, a cardiopulmonary bypass (CPB) with selective antegrade cerebral perfusion (ACP) is employed during aortic arch reconstruction to protect cerebral circulation. However, the use of CPB carries inherent higher risks, including embolic events, hypothermia, and interrupted cerebral perfusion, especially in patients with CM. This study evaluates an innovative off-pump extra-corporeal ACP technique using an axillo-axillary shunt to provide uninterrupted bihemispheric cerebral perfusion during branch-first stage total aortic arch replacement (BF-TAR) for TAAD with CM; the shunt depends on cardiac contradiction to transfuse blood from the donor axillary artery to the recipient axillary artery, which then flows to through the carotid and vertebral arteries to the brain. Methods Between 2021 and 2023, 18 patients with TAAD complicated by CM underwent BF-TAR; the novel axillo-axillary shunt technique was employed for ACP because of the risks of ischemic neurologic injury. Outcomes measured included operative mortality, neurological complications, cardiopulmonary bypass times (measured after completion of the branch-first stage), and overall morbidity. Results The axillo-axillary shunt provided stable, continuous ACP in all patients. No new permanent neurological deficits were observed. Five (27.8%) patients experienced transient neurological symptoms such as blurred vision, dizziness, and confusion, which resolved within 48 hours. Operative mortality was 5.6% (1 patient), and minor complications included transitory lower limbs ischemia in 3 patients (16.7%) and deep sternal wound infection in 1 patient (5.6%). All transitory complications were managed by "watchful waiting". The mean CPB time was 145.3 ± 48.6 minutes, while the mean cross-clamp time was 100.6 ± 17.4 minutes, which was better than the average of 227 ± 32 minutes and 147 ± 23 minutes reported in other studies. Postoperative imaging confirmed well-reconstructed aortic arches with no residual malperfusion or graft-related complications. Conclusion The off-pump axillo-axillary shunt technique provides a safe and effective method for maintaining continuous bihemispheric cerebral perfusion during total aortic arch replacement in patients with TAAD complicated by CM. This approach minimizes the risks associated with CPB, including embolic events and interrupted cerebral perfusion while achieving favorable neurological and surgical outcomes. Further studies with larger cohorts and longer follow-ups are warranted to validate the long-term benefits of this innovative technique.

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

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

Application of the Single Source-Detector Separation Algorithm in Wearable Neuroimaging Devices: A Step toward Miniaturized Biosensor for Hypoxia Detection

Most currently available wearable devices to noninvasively detect hypoxia use the spatially resolved spectroscopy (SRS) method to calculate cerebral tissue oxygen saturation (StO2). This study applies the single source-detector separation (SSDS) algorithm to calculate StO2. Near-infrared spectroscopy (NIRS) data were collected from 26 healthy adult volunteers during a breath-holding task using a wearable NIRS device, which included two source-detector separations (SDSs). These data were used to derive oxyhemoglobin (HbO) change and StO2. In the group analysis, both HbO change and StO2 exhibited significant change during a breath-holding task. Specifically, they initially decreased to minimums at around 10 s and then steadily increased to maximums, which were significantly greater than baseline levels, at 25-30 s (p-HbO < 0.001 and p-StO2 < 0.05). However, at an individual level, the SRS method failed to detect changes in cerebral StO2 in response to a short breath-holding task. Furthermore, the SSDS algorithm is more robust than the SRS method in quantifying change in cerebral StO2 in response to a breath-holding task. In conclusion, these findings have demonstrated the potential use of the SSDS algorithm in developing a miniaturized wearable biosensor to monitor cerebral StO2 and detect cerebral hypoxia.

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.

Surgical management of calcific valvular and coronary disease in a patient with alkaptonuria: a case report

Background

Alkaptonuria is a rare metabolic disease that causes an increase in homogentisic acid (HGA) due to a lack of enzymatic activity. Commonly, accumulation of HGA presents with dark discoloration of skin and other tissues, also known as ochronosis. Additionally, alkaptonuria can result in other clinical manifestations, including arthritis and cardiac disease. This case highlights alkaptonuria-related cardiac disease and challenges that cardiac surgery teams may face when treating this patient population.

Case summary

A 62-year-old male with a history of alkaptonuria, Hodgkin's lymphoma treated with chemoradiation, hypertension, and hyperlipidaemia originally presented with shortness of breath in the setting of known cardiac disease. Cardiac work-up demonstrated aortic stenosis, mitral stenosis, and multivessel coronary artery disease requiring aortic valve replacement, mitral valve replacement, and coronary artery bypass grafting. During the operation, significant discoloration of tissue was observed. This correlated with areas of severe calcification, which was noted throughout both valves. Extensive debridement was required prior to proceeding to valve replacements. Additionally, near-infrared spectroscopy failed to provide accurate measurements of cerebral oxygenation.

Discussion

Alkaptonuria is correlated with cardiovascular disease, particularly valvular disease. Intraoperatively, these patients may exhibit noticeable discoloration and severe calcification of various tissues. Additionally, traditional infrared-based methods of cerebral oxygenation monitoring may not be reliable; however, other options of cerebral monitoring may be feasible. With proper pre-operative planning, however, patients with alkaptonuria may safely undergo cardiac surgery.

The Impact of Inotropes and Vasopressors on Cerebral Oxygenation in Patients with Traumatic Brain Injury and Subarachnoid Hemorrhage: A Narrative Review

Traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH) are critical neurological conditions that necessitate specialized care in the Intensive Care Unit (ICU). Managing cerebral perfusion pressure (CPP) and mean arterial pressure (MAP) is of primary importance in these patients. To maintain targeted MAP and CPP, vasopressors and/or inotropes are commonly used. However, their effects on cerebral oxygenation are not fully understood. The aim of this review is to provide an up-to date review regarding the current uses and pathophysiological issues related to the use of vasopressors and inotropes in TBI and SAH patients. According to our findings, despite achieving similar hemodynamic parameters and CPP, the effects of various vasopressors and inotropes on cerebral oxygenation, local CBF and metabolism are heterogeneous. Therefore, a more accurate understanding of the cerebral activity of these medications is crucial for optimizing patient management in the ICU setting.

A Physical Fatigue Evaluation Method for Automotive Manual Assembly: An Experiment of Cerebral Oxygenation with ARE Platform

Due to the complexity of the automobile manufacturing process, some flexible and delicate assembly work relies on manual operations. However, high-frequency and high-load repetitive operations make assembly workers prone to physical fatigue. This study proposes a method for evaluating human physical fatigue for the manual assembly of automobiles with methods: NIOSH (National Institute for Occupational Safety and Health), OWAS (Ovako Working Posture Analysis System) and RULA (Rapid Upper Limb Assessment). The cerebral oxygenation signal is selected as an objective physiological index reflecting the human fatigue level to verify the proposed physical fatigue evaluation method. Taking auto seat assembly and automobile manual assembly as an example, 18 group experiments were carried out with the ARE platform (Augmented Reality-based Ergonomic Platform). Furthermore, predictions of metabolic energy expenditure were performed for experiments in Tecnomatix Jack. Finally, it is concluded that the proposed physical fatigue evaluation method can reflect the human physical fatigue level and is more accurate than the evaluation of metabolic energy consumption in Tecnomatix Jack because of the immersion that comes with the AR devices and the precision that comes with motion capture devices.

Evaluation of markers of cerebral oxygenation and metabolism in patients undergoing clipping of cerebral aneurysm under total intravenous anesthesia versus inhalational anesthesia: A prospective randomized trial (COM-IVIN trial)

INTRODUCTION

Anesthetic goals in patients undergoing clipping of cerebral aneurysm include maintenance of cerebral blood flow, oxygenation, and metabolism to avoid cerebral ischemia and maintenance of hemodynamic stability. We intend to study the influence of anesthetic agents on the outcome of aneurysmal subarachnoid hemorrhage (SAH).

MATERIALS AND METHODS

This is a prospective, randomized, parallel, single-center pilot trial approved by the Institutional Ethics Committee and is prospectively registered with the Clinical Trial Registry of India. Patients with aneurysmal SAH (aSAH) admitted to our institution for surgical clipping, fulfilling the trial inclusion criteria, will be randomized in a 1:1 allocation ratio utilizing a computerized random allocation sequence to receive either total intravenous anesthesia (n = 25) or inhalational anesthesia (n = 25). Our primary objective is to study the effects of these anesthetic techniques on cerebral oxygenation and metabolism in patients with aSAH. Our secondary objective is to evaluate the impact of these anesthetic techniques on the incidence of delayed cerebral ischemia and long-term patient outcomes in patients with aSAH. The Modified Rankin Score and Glasgow Outcome Scale (GOS) at discharge and 3 months following hospital discharge will be evaluated. An observer blinded to the study intervention will assess the outcome measures.

DISCUSSION

This study will provide more insight as to which is the ideal anesthetic agent that offers a better neurophysiological profile regarding intraoperative cerebral oxygenation and metabolism, thereby contributing to better postoperative outcomes in aSAH patients.

Intraoperative application of regional cerebral oxygen saturation monitoring for geriatric patients in China: a survey

Background

Regional cerebral oxygen saturation (rSO2) monitoring is a real-time and non-invasive technique for estimating the balance of regional cerebral oxygen supply and consumption. Despite the growing popularity of this monitoring technique, data regarding outcome benefits remain sparse and contradictory. This study was conducted to explore the popularity and understanding of cerebral oxygen saturation monitoring during anesthesia in geriatric patients.

Methods

An online self-report questionnaire was distributed in March 2021 to various hospitals in China for dissemination to anesthesiologists. Questions surveyed cerebral oximetry equipment and utilization, demographics, and clinical practice of participants.

Results

In total, 447 anesthesiologists responded. Of these, 301 (67.3%) respondents reported that their hospitals were equipped with cerebral oximetry, which 274 anesthesiologists use during anesthesia. A high percentage of anesthesiologists chose to monitor rSO2 during cardiac surgery (77.4%, n = 212) and neurosurgery (40.5%, n = 111). Most anesthesiologists agreed that a 30% reduction from the rSO2 baseline requires intervention to avoid cerebral ischemia, mainly via elevating arterial pressure and fraction of inspired oxygen (FiO2). Of those without cerebral oximetry, 138 of 146 (94.5%) anesthesiologists were willing to monitor rSO2. In addition, 291 respondents believed that cerebral oxygen monitoring would help prevent postoperative cognitive dysfunction.

Conclusion

Our survey indicated that the prevalence of cerebral oximetry remains relatively low, while almost all anesthesiologists expressed their willingness to use rSO2 monitoring in geriatric anesthesia. Heterogeneity in clinical practice was identified, indicating relevant knowledge gaps that should encourage further clinical research to optimize treatment.

Biophysiologic Monitoring for the Neurosurgical Patient

Biophysiologic monitoring exists as a method of collecting objective information about the neurosurgical patient throughout their treatment and recovery process. Such data is crucial for an improved understanding of the disease processes while providing the surgeon additional clarity as they decipher the next best steps in decision-making and medical recommendations. In the current review article, the authors discuss the commonly used wearable and placeable monitoring devices and the biophysiological data that can be collected to monitor, as well as, assess the neurosurgical patient. Special focus is placed on invasive and non-invasive neurologic monitoring devices, but important and commonly used monitors for the rest of the body are also discussed as they relate to the neurosurgical patient. Last, the authors review new, as well as, upcoming devices and measurements to better analyze the neurosurgical patient's bodily function and physiologic status as needed. The synthesis of methods contained herein may provide meaningful guidance for neurosurgeons in effectively monitoring and treating their patients while also helping to guide their future efforts in patient biophysiologic monitoring developments within neurosurgery.

Invasive Neuromonitoring in the Stroke Patient

With advances in technology, the options to manage patients with neurologic injuries are often complex. Critical care management of neurologic injury has historically focused on the prevention of secondary ischemic injury through aggressive management of intracranial pressure (ICP) and maintenance of adequate cerebral perfusion pressure (CPP). However, ICP monitoring alone does not identify ischemic changes that herald patient deterioration. Advocates of multimodality monitoring cite the value of early detection of changes in brain oxygenation levels and brain metabolism as advantageous in optimizing stroke outcomes. ICP monitoring alone should not be the sole source of information on which therapy is guided but should be incorporated into the arsenal of emerging and promising invasive neuromonitoring devices.

In-hospital mortality and SpO2 incritical care patients with cerebral injury: data from the MIMIC‑IV Database

BACKGROUND

Evidence regarding the relationship between in-hospital mortality and SpO2 was low oxygen saturations are often thought to be harmful, new research in patients with brain damage has found that high oxygen saturation actually enhances mortality. However, there is currently no clear study to point out the appropriate range for oxygen saturation in patients with craniocerebral diseases.  METHODS: By screening all patients in the MIMIC IV database, 3823 patients with craniocerebral diseases (according to ICD-9 codes and ICD-10) were selected, and non-linear regression was used to analyze the relationship between in-hospital mortality and oxygen saturation. Covariates for all patients included age, weight, diagnosis, duration of ICU stay, duration of oxygen therapy, etc. RESULTS: In-hospital mortality in patients with TBI and SAH was kept to a minimum when oxygen saturation was in the 94-96 range. And in all patients, the relationship between oxygen saturation and in-hospital mortality was U-shaped. Subgroup analysis of the relationship between oxygen saturation and mortality in patients with metabolic encephalopathy and other encephalopathy also draws similar conclusions In-hospital mortality and oxygen saturation were all U-shaped in patients with subarachnoid hemorrhage, metabolic and toxic encephalopathy, cerebral infarction, and other encephalopathy, but the nonlinear regression was statistically significant only in patients with cerebral infarction (p for nonlinearity = 0.002).

CONCLUSION

Focusing too much on the lower limit of oxygen saturation and ignoring too high oxygen saturation can also lead to increase in-hospital mortality. For patients with TBI and SAH, maintaining oxygen saturation at 94-96% will minimize the in-hospital mortality of patients.

Intraoperative Optical Monitoring of Spinal Cord Hemodynamics Using Multiwavelength Imaging System

The spinal cord is a major structure of the central nervous system allowing, among other things, the transmission of afferent sensory and efferent motor information. During spinal surgery, such as scoliosis correction, this structure can be damaged, resulting in major neurological damage to the patient. To date, there is no direct way to monitor the oxygenation of the spinal cord intraoperatively to reflect its vitality. This is essential information that would allow surgeons to adapt their procedure in case of ischemic suffering of the spinal cord. We report the development of a specific device to monitor the functional status of biological tissues with high resolution. The device, operating with multiple wavelengths, uses Near-InfraRed Spectroscopy (NIRS) in combination with other additional sensors, including ElectroNeuroGraphy (ENG). In this paper, we focused primarily on aspects of the PhotoPlethysmoGram (PPG), emanating from four different light sources to show in real time and record biological signals from the spinal cord in transmission and reflection modes. This multispectral system was successfully tested in in vivo experiments on the spinal cord of a pig for specific medical applications.

Gender difference in functional activity of 4-months-old infants during sleep: A functional near-infrared spectroscopy study

Sex differences emerge early in infancy. A number of earlier studies have investigated the resting-state network of infant sleep states, and there have been many studies using functional near-infrared spectroscopy (fNIRS) to examine the effects of infant language learning on changes in oxyhemoglobin and deoxyhemoglobin levels. However, studies examining sex differences from the resting-state network of infant sleep states are scarce. This study uses an open access dataset of task-free hemodynamic activity in 4-month-old infants during sleep by fNIRS, to identify some difference between male and female infants. We used Power Spectral Density showing at which frequencies the data variation/variance is high. We have also analyzed some gender differences by analyzing the relationship between individual channels, the degree of activation, etc. The results of this study showed that female and male infants had different Power Spectral Density for oxyhemoglobin and deoxyhemoglobin at rest, showing stronger differences at frontoparietal network, somatomotor network, visual network and dorsal network. This may be due to the differences in the timing or extent of development of those networks. These differences will provide some assistance in future studies of the early education of male and female infants.