The role of carbon dioxide in acute brain injury

Training in neonatal neurocritical care: A case-based interdisciplinary approach

Interdisciplinary fetal-neonatal neurology (FNN) training strengthens neonatal neurocritical care (NNCC) clinical decisions. Neonatal neurological phenotypes require immediate followed by sustained neuroprotective care path choices through discharge. Serial assessments during neonatal intensive care unit (NICU) rounds are supplemented by family conferences and didactic interactions. These encounters collectively contribute to optimal interventions yielding more accurate outcome predictions. Maternal-placental-fetal (MPF) triad disease pathways influence postnatal medical complications which potentially reduce effective interventions and negatively impact outcome. The science of uncertainty regarding each neonate's clinical status must consider timing and etiologies that are responsible for fetal and neonatal brain disorders. Shared clinical decisions among all stakeholders' balance "fast" (heuristic) and "slow" (analytic) thinking as more information is assessed regarding etiopathogenetic effects that impair the developmental neuroplasticity process. Two case vignettes stress the importance of FNN perspectives during NNCC that integrates this dual cognitive approach. Clinical care paths evaluations are discussed for an encephalopathic extremely preterm and full-term newborn. Recognition of cognitive errors followed by debiasing strategies can improve clinical decisions during NICU care. Re-evaluations with serial assessments of examination, imaging, placental-cord, and metabolic-genetic information improve clinical decisions that maintain accuracy for interventions and outcome predictions. Discharge planning includes shared decisions among all stakeholders when coordinating primary care, pediatric subspecialty, and early intervention participation. Prioritizing social determinants of healthcare during FNN training strengthens equitable career long NNCC clinical practice, education, and research goals. These perspectives contribute to a life course brain health capital strategy that will benefit all persons across each and successive lifespans.

Interleaved Propofol-Ketamine Maintains DBS Physiology and Hemodynamic Stability: A Double-Blind Randomized Controlled Trial

BACKGROUND

The gold standard anesthesia for deep brain stimulation (DBS) surgery is the "awake" approach, using local anesthesia alone. Although it offers high-quality microelectrode recordings and therapeutic-window assessment, it potentially causes patients extreme stress and might result in suboptimal surgical outcomes. General anesthesia or deep sedation is an alternative, but may reduce physiological testing reliability and lead localization accuracy.

OBJECTIVES

The aim is to investigate a novel anesthesia regimen of ketamine-induced conscious sedation for the physiological testing phase of DBS surgery.

METHODS

Parkinson's patients undergoing subthalamic DBS surgery were randomly divided into experimental and control groups. During physiological testing, the groups received 0.25 mg/kg/h ketamine infusion and normal saline, respectively. Both groups had moderate propofol sedation before and after physiological testing. The primary outcome was recording quality. Secondary outcomes included hemodynamic stability, lead accuracy, motor and cognitive outcome, patient satisfaction, and adverse events.

RESULTS

Thirty patients, 15 from each group, were included. Intraoperatively, the electrophysiological signature and lead localization were similar under ketamine and saline. Tremor amplitude was slightly lower under ketamine. Postoperatively, patients in the ketamine group reported significantly higher satisfaction with anesthesia. The improvement in Unified Parkinson's disease rating scale part-III was similar between the groups. No negative effects of ketamine on hemodynamic stability or cognition were reported perioperatively.

CONCLUSIONS

Ketamine-induced conscious sedation provided high quality microelectrode recordings comparable with awake conditions. Additionally, it seems to allow superior patient satisfaction and hemodynamic stability, while maintaining similar post-operative outcomes. Therefore, it holds promise as a novel alternative anesthetic regimen for DBS. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Perioperative management of adults with traumatic brain injury

Despite advances in management strategy, traumatic brain injury remains strongly associated with neurological impairment and mortality. Management of traumatic brain injury requires careful and targeted management of the physiological consequences which extend beyond the scope of the primary impact to the cranium. Here, we present a review of the principles of its acute management in adults. We outline the procedure which patients are assessed and the critical physiological variables which must be monitored to prevent further neurological damage. We describe current interventional strategies from the context of the underlying physiological mechanisms and recent clinical data and identify persisting challenges in traumatic brain injury management and potential avenues of future progress.

Future directions in ventilator-induced lung injury associated cognitive impairment: a new sight

Mechanical ventilation is a widely used short-term life support technique, but an accompanying adverse consequence can be pulmonary damage which is called ventilator-induced lung injury (VILI). Mechanical ventilation can potentially affect the central nervous system and lead to long-term cognitive impairment. In recent years, many studies revealed that VILI, as a common lung injury, may be involved in the central pathogenesis of cognitive impairment by inducing hypoxia, inflammation, and changes in neural pathways. In addition, VILI has received attention in affecting the treatment of cognitive impairment and provides new insights into individualized therapy. The combination of lung protective ventilation and drug therapy can overcome the inevitable problems of poor prognosis from a new perspective. In this review, we summarized VILI and non-VILI factors as risk factors for cognitive impairment and concluded the latest mechanisms. Moreover, we retrospectively explored the role of improving VILI in cognitive impairment treatment. This work contributes to a better understanding of the pathogenesis of VILI-induced cognitive impairment and may provide future direction for the treatment and prognosis of cognitive impairment.

Spatiotemporal features of neurovascular (un)coupling with stimulus-induced activity and hypercapnia challenge in cerebral cortex and olfactory bulb

Carbon dioxide (CO2) is traditionally considered as metabolic waste, yet its regulation is critical for brain function. It is well accepted that hypercapnia initiates vasodilation, but its effect on neuronal activity is less clear. Distinguishing how stimulus- and CO2-induced vasodilatory responses are (dis)associated with neuronal activity has profound clinical and experimental relevance. We used an optical method in mice to simultaneously image fluorescent calcium (Ca2+) transients from neurons and reflectometric hemodynamic signals during brief sensory stimuli (i.e., hindpaw, odor) and CO2 exposure (i.e., 5%). Stimuli-induced neuronal and hemodynamic responses swiftly increased within locally activated regions exhibiting robust neurovascular coupling. However, hypercapnia produced slower global vasodilation which was temporally uncoupled to neuronal deactivation. With trends consistent across cerebral cortex and olfactory bulb as well as data from GCaMP6f/jRGECO1a mice (i.e., green/red Ca2+ fluorescence), these results unequivocally reveal that stimuli and CO2 generate comparable vasodilatory responses but contrasting neuronal responses. In summary, observations of stimuli-induced regional neurovascular coupling and CO2-induced global neurovascular uncoupling call for careful appraisal when using CO2 in gas mixtures to affect vascular tone and/or neuronal excitability, because CO2 is both a potent vasomodulator and a neuromodulator.

Functional Two-Way Crosstalk Between Brain and Lung: The Brain-Lung Axis

The brain has many connections with various organs. Recent advances have demonstrated the existence of a bidirectional central nervous system (CNS) and intestinal tract, that is, the brain-gut axis. Although studies have suggested that the brain and lung can communicate with each other through many pathways, whether there is a brain-lung axis remains still unknown. Based on previous findings, we put forward a hypothesis: there is a cross-talk between the central nervous system and the lung via neuroanatomical pathway, endocrine pathway, immune pathway, metabolites and microorganism pathway, gas pathway, that is, the brain-lung axis. Beyond the regulation of the physiological state in the body, bi-directional communication between the lung and the brain is associated with a variety of disease states, including lung diseases and CNS diseases. Exploring the brain-lung axis not only helps us to understand the development of the disease from different aspects, but also provides an important target for treatment strategies.

Systemic immune inflammation index and peripheral blood carbon dioxide concentration at admission predict poor prognosis in patients with severe traumatic brain injury

Background

Recent studies have shown that systemic inflammation responses and hyperventilation are associated with poor outcomes in patients with severe traumatic brain injury (TBI). The aim of this retrospective study was to investigate the relationships between the systemic immune inflammation index (SII = platelet × neutrophil/lymphocyte) and peripheral blood CO₂ concentration at admission with the Glasgow Outcome Score (GOS) at 6 months after discharge in patients with severe TBI.

Methods

We retrospectively analyzed the clinical data for 1266 patients with severe TBI at three large medical centers from January 2016 to December 2021, and recorded the GOS 6 months after discharge. The receiver operating characteristic (ROC) curve was used to determine the best cutoff values for SII, CO₂, neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and lymphocyte to monocyte ratio (LMR), and chi-square tests were used to evaluate the relationships among SII, CO₂ and the basic clinical characteristics of patients with TBI. Multivariate logistic regression analysis was used to determine the independent prognostic factors for GOS in patients with severe TBI. Finally, ROC curve, nomogram, calibration curve and decision curve analyses were used to evaluate the value of SII and coSII-CO2 in predicting the prognosis of patients with severe TBI. And we used the multifactor regression analysis method to build the CRASH model and the IMPACT model. The CRASH model included age, GCS score (GCS, Glasgow Coma Scale) and Pupillary reflex to light: one, both, none. The IMPACT model includes age, motor score and Pupillary reflex to light: one, both, none.

Results

The ROC curves indicated that the best cutoff values of SII, CO₂, PLR, NLR and LMR were 2651.43×10⁹, 22.15mmol/L, 190.98×10⁹, 9.66×10⁹ and 1.5×10⁹, respectively. The GOS at 6 months after discharge of patients with high SII and low CO₂ were significantly poorer than those with low SII and high CO₂. Multivariate logistic regression analysis revealed that age, systolic blood pressure (SBP), pupil size, subarachnoid hemorrhage (SAH), SII, PLR, serum potassium concentration [K⁺], serum calcium concentration [Ca²⁺], international normalized ratio (INR), C-reactive protein (CRP) and co-systemic immune inflammation index combined with carbon dioxide (coSII-CO₂) (P < 0.001) were independent prognostic factors for GOS in patients with severe TBI. In the training group, the C-index was 0.837 with SII and 0.860 with coSII-CO₂. In the external validation group, the C-index was 0.907 with SII and 0.916 with coSII-CO₂. Decision curve analysis confirmed a superior net clinical benefit with coSII-CO₂ rather than SII in most cases. Furthermore, the calibration curve for the probability of GOS 6 months after discharge showed better agreement with the observed results when based on the coSII-CO₂ rather than the SII nomogram. According to machine learning, coSII-CO₂ ranked first in importance and was followed by pupil size, then SII.

Conclusions

SII and CO₂ have better predictive performance than NLR, PLR and LMR. SII and CO₂ can be used as new, accurate and objective clinical predictors, and coSII-CO₂, based on combining SII with CO₂, can be used to improve the accuracy of GOS prediction in patients with TBI 6 months after discharge.

NO, CO and H2S: A Trinacrium of Bioactive Gases in the Brain

Oxygen and carbon dioxide are time honored gases that have direct bearing on almost all life forms, but over the past thirty years, and in large part due to the Nobel Prize Award in Medicine for the elucidation of nitric oxide (NO) as a bioactive gas, the research and medical communities now recognize other gases as critical for survival. In addition to NO, hydrogen sulfide (H₂S) and carbon monoxide (CO) have emerged as a triumvirate or Trinacrium of gases with analogous importance and that serve important homeostatic functions. Perhaps, one of the most intriguing aspects of these gases is the functional interaction between them, which is intimately linked by the enzyme systems that produce them. Despite the need to better understand NO, H₂S and CO biology, the notion that these are environmental pollutants remains ever present. For this reason, incorporating the concept of hormesis becomes imperative and must be included in discussions when considering developing new therapeutics that involve these gases. While there is now an enormous literature base for each of these gasotransmitters, we provide here an overview of their respective physiologic roles in the brain.

Clinical Effectiveness of Pre-hospital and In-hospital Optimized Emergency Care Procedures for Patients With Acute Craniocerebral Trauma

Acute craniocerebral injury is a common traumatic disease in clinical practice, characterized by rapid changes in condition and a high rate of death and disability. Early and effective emergency care throughout the pre-hospital and in-hospital period is the key to reducing the rate of death and disability and promoting the recovery of patients. In this study, we conducted an observational study of 130 patients with acute craniocerebral injury admitted between May 2020 and May 2021. Patients were randomly divided into a regular group and an optimization group of 65 patients each, with patients in the regular group receiving the conventional emergency care model and patients in the optimization group receiving the pre-hospital and in-hospital optimal emergency care process for intervention. In this study, we observed and compared the time taken to arrive at the scene, assess the condition, attend to the patient and provide emergency care, the success rate of emergency care within 48 h, the interleukin-6 (IL-6), interleukin-8 (IL-8), and intercellular adhesion molecule-1 (ICAM-1) after admission and 1 day before discharge, the National Institute of Health Stroke Scale (NIHSS) and the Short Form 36-item Health Survey (SF-36) after resuscitation and 1 day before discharge, and the complications of infection, brain herniation, central hyperthermia, and electrolyte disturbances in both groups. We collected and statistically analyzed the recorded data. The results showed that the time taken to arrive at the consultation site, assess the condition, receive the consultation, provide first aid was significantly lower in the optimized group than in the regular group (P < 0.05); the success rate of treatment was significantly higher in the optimized group than in the regular group (P < 0.05). In both groups, IL-6, IL-8, and ICAM-1 decreased on the day before discharge compared with the day of rescue, with the levels of each index lower in the optimization group than in the regular group (P < 0.05); the NIHSS scores decreased and the SF-36 scores increased on the day before discharge compared with the successful rescue in both groups, with the NIHSS scores in the optimization group lower than in the regular group and the SF-36 scores higher than in the control group (P < 0.05). The overall complication rate in the optimization group was significantly lower than that in the regular group (P < 0.05). This shows that optimizing pre-hospital and in-hospital emergency care procedures can significantly shorten the time to emergency care for patients with acute craniocerebral injury, increase the success rate, reduce inflammation, improve neurological function and quality of life, reduce the occurrence of complications, and improve patient prognosis.

Neuroprotective Potential of Mild Uncoupling in Mitochondria. Pros and Cons

There has been an explosion of interest in the use of uncouplers of oxidative phosphorylation in mitochondria in the treatment of several pathologies, including neurological ones. In this review, we analyzed all the mechanisms associated with mitochondrial uncoupling and the metabolic and signaling cascades triggered by uncouplers. We provide a full set of positive and negative effects that should be taken into account when using uncouplers in experiments and clinical practice.

Lessons from NATURE: methods for traumatic brain injury prevention

Multiple species obtain repetitive head collisions throughout the course of their lifetimes with minimal neurologic deficit. Nature has allowed the unique development of multiple protective mechanisms to help prevent neurotrauma. In this review, we examine the concept of rapid brain movement within the skull 'Slosh' and what nature teaches on how to prevent this from occurring. We look at individual animals and the protective mechanisms at play. Marching from macroscopic down to the molecular level, we pinpoint key elements of neuroprotection that are likely contributing. We also introduce new concepts for neuroprotection and address avenues of further discovery.

The therapeutic importance of acid-base balance

Baking soda and vinegar have been used as home remedies for generations and today we are only a mouse-click away from claims that baking soda, lemon juice, and apple cider vinegar are miracles cures for everything from cancer to COVID-19. Despite these specious claims, the therapeutic value of controlling acid-base balance is indisputable and is the basis of Food and Drug Administration-approved treatments for constipation, epilepsy, metabolic acidosis, and peptic ulcers. In this narrative review, we present evidence in support of the current and potential therapeutic value of countering local and systemic acid-base imbalances, several of which do in fact involve the administration of baking soda (sodium bicarbonate). Furthermore, we discuss the side effects of pharmaceuticals on acid-base balance as well as the influence of acid-base status on the pharmacokinetic properties of drugs. Our review considers all major organ systems as well as information relevant to several clinical specialties such as anesthesiology, infectious disease, oncology, dentistry, and surgery.