Tackling Brain and Muscle Dysfunction in Acute Respiratory Distress Syndrome Survivors: NHLBI Workshop Report.

Acute respiratory distress syndrome (ARDS) is associated with long-term impairments in brain and muscle function that significantly impact the quality of life of those who survive the acute illness. The mechanisms underlying these impairments are not yet well understood, and evidence-based interventions to minimize the burden on patients remain unproved. The NHLBI of the NIH assembled a workshop in April 2023 to review the state of the science regarding ARDS-associated brain and muscle dysfunction, to identify gaps in current knowledge, and to determine priorities for future investigation. The workshop included presentations by scientific leaders across the translational science spectrum and was open to the public as well as the scientific community. This report describes the themes discussed at the workshop as well as recommendations to advance the field toward the goal of improving the health and well-being of ARDS survivors.

Preclinical and translational models for delirium: Recommendations for future research from the NIDUS delirium network.

Delirium is a common, morbid, and costly syndrome that is closely linked to Alzheimer's disease (AD) and AD-related dementias (ADRD) as a risk factor and outcome. Human studies of delirium have advanced our knowledge of delirium incidence and prevalence, risk factors, biomarkers, outcomes, prevention, and management. However, understanding of delirium neurobiology remains limited. Preclinical and translational models for delirium, while challenging to develop, could advance our knowledge of delirium neurobiology and inform the development of new prevention and treatment approaches. We discuss the use of preclinical and translational animal models in delirium, focusing on (1) a review of current animal models, (2) challenges and strategies for replicating elements of human delirium in animals, and (3) the utility of biofluid, neurophysiology, and neuroimaging translational markers in animals. We conclude with recommendations for the development and validation of preclinical and translational models for delirium, with the goal of advancing awareness in this important field.

Acute kidney injury-associated delirium: a review of clinical and pathophysiological mechanisms.

Acute kidney injury is a known clinical risk factor for delirium, an acute cognitive dysfunction that is commonly encountered in the critically ill population. In this comprehensive review of clinical and basic research studies, we detail the epidemiology, clinical implications, pathogenesis, and management strategies of patients with acute kidney injury-associated delirium. Specifically addressed are the pathological roles of endogenous toxin or drug accumulation, acute kidney injury-mediated neuroinflammation, and acute kidney injury-associated volume overload as discrete potential biological mechanisms of the condition. The optimization of clinical contributors and normalization of renal function are reviewed as pragmatic management strategies in addition to potential and emerging therapeutic approaches.

Systemic interleukin-6 inhibition ameliorates acute neuropsychiatric phenotypes in a murine model of acute lung injury.

Acute neuropsychiatric impairments occur in over 70% of patients with acute lung injury. Mechanical ventilation is a well-known precipitant of acute lung injury and is strongly associated with the development of acute delirium and anxiety phenotypes. In prior studies, we demonstrated that IL-6 mediates neuropathological changes in the frontal cortex and hippocampus of animals with mechanical ventilation-induced brain injury; however, the effect of systemic IL-6 inhibition on structural and functional acute neuropsychiatric phenotypes is not known. We hypothesized that a murine model of mechanical ventilation-induced acute lung injury (VILI) would induce neural injury to the amygdala and hippocampus, brain regions that are implicated in diverse neuropsychiatric conditions, and corresponding delirium- and anxiety-like functional impairments. Furthermore, we hypothesized that these structural and functional changes would reverse with systemic IL-6 inhibition. VILI was induced using high tidal volume (35 cc/kg) mechanical ventilation. Cleaved caspase-3 (CC3) expression was quantified as a neural injury marker and found to be significantly increased in the VILI group compared to spontaneously breathing or anesthetized and mechanically ventilated mice with 10 cc/kg tidal volume. VILI mice treated with systemic IL-6 inhibition had significantly reduced amygdalar and hippocampal CC3 expression compared to saline-treated animals and demonstrated amelioration in acute neuropsychiatric behaviors in open field, elevated plus maze, and Y-maze tests. Overall, these data provide evidence of a pathogenic role of systemic IL-6 in mediating structural and functional acute neuropsychiatric symptoms in VILI and provide preclinical justification to assess IL-6 inhibition as a potential intervention to ameliorate acute neuropsychiatric phenotypes following VILI.

IL-6 Inhibition Reduces Neuronal Injury in a Murine Model of Ventilator-induced Lung Injury.

Mechanical ventilation is a known risk factor for delirium, a cognitive impairment characterized by dysfunction of the frontal cortex and hippocampus. Although IL-6 is upregulated in mechanical ventilation-induced lung injury (VILI) and may contribute to delirium, it is not known whether the inhibition of systemic IL-6 mitigates delirium-relevant neuropathology. To histologically define neuropathological effects of IL-6 inhibition in an experimental VILI model, VILI was simulated in anesthetized adult mice using a 35 cc/kg tidal volume mechanical ventilation model. There were two control groups, as follow: 1) spontaneously breathing or 2) anesthetized and mechanically ventilated with 10 cc/kg tidal volume to distinguish effects of anesthesia from VILI. Two hours before inducing VILI, mice were treated with either anti-IL-6 antibody, anti-IL-6 receptor antibody, or saline. Neuronal injury, stress, and inflammation were assessed using immunohistochemistry. CC3 (cleaved caspase-3), a neuronal apoptosis marker, was significantly increased in the frontal (P < 0.001) and hippocampal (P < 0.0001) brain regions and accompanied by significant increases in c-Fos and heat shock protein-90 in the frontal cortices of VILI mice compared with control mice (P < 0.001). These findings were not related to cerebral hypoxia, and there was no evidence of irreversible neuronal death. Frontal and hippocampal neuronal CC3 were significantly reduced with anti-IL-6 antibody (P < 0.01 and P < 0.0001, respectively) and anti-IL-6 receptor antibody (P < 0.05 and P < 0.0001, respectively) compared with saline VILI mice. In summary, VILI induces potentially reversible neuronal injury and inflammation in the frontal cortex and hippocampus, which is mitigated with systemic IL-6 inhibition. These data suggest a potentially novel neuroprotective role of systemic IL-6 inhibition that justifies further investigation.

Interleukin-6 mediates delirium-like phenotypes in a murine model of urinary tract infection.

BACKGROUND: Urinary tract infection (UTI) is frequently implicated as a precipitant of delirium, which refers to an acute confusional state that is associated with high mortality, increased length of stay, and long-term cognitive decline. The pathogenesis of delirium is thought to involve cytokine-mediated neuronal dysfunction of the frontal cortex and hippocampus. We hypothesized that systemic IL-6 inhibition would mitigate delirium-like phenotypes in a mouse model of UTI. METHODS: C57/BL6 mice were randomized to either: (1) non-UTI control, (2) UTI, and (3) UTI + anti-IL-6 antibody. UTI was induced by transurethral inoculation of 1 × 108 Escherichia coli. Frontal cortex and hippocampus-mediated behaviors were evaluated using functional testing and corresponding structural changes were evaluated via quantification of neuronal cleaved caspase-3 (CC3) by immunohistochemistry and western blot. IL-6 in the brain and plasma were evaluated using immunohistochemistry, ELISA, and RT-PCR. RESULTS: Compared to non-UTI control mice, mice with UTI demonstrated significantly greater impairments in frontal and hippocampus-mediated behaviors, specifically increased thigmotaxis in Open Field (p < 0.05) and reduced spontaneous alternations in Y-maze (p < 0.01), while treatment of UTI mice with systemic anti-IL-6 fully reversed these functional impairments. These behavioral impairments correlated with frontal and hippocampal neuronal CC3 changes, with significantly increased frontal and hippocampal CC3 in UTI mice compared to non-UTI controls (p < 0.0001), and full reversal of UTI-induced CC3 neuronal changes following treatment with systemic anti-IL-6 antibody (p < 0.0001). Plasma IL-6 was significantly elevated in UTI mice compared to non-UTI controls (p < 0.01) and there were positive and significant correlations between plasma IL-6 and frontal CC3 (r2 = 0.5087/p = 0.0028) and frontal IL-6 and CC3 (r2 = 0.2653, p < 0.0001). CONCLUSIONS: These data provide evidence for a role for IL-6 in mediating delirium-like phenotypes in a mouse model of UTI. These findings provide pre-clinical justification for clinical investigations of IL-6 inhibitors to treat UTI-induced delirium.

Self-perceptions on cognitive versus motor disability among neurologists.

OBJECTIVE: The modified Rankin Scale is a functional outcome measure that disproportionately represents motor deficits. We hypothesize that among physicians who most commonly use the modified Rankin Scale to counsel patients on neurological treatment options, personal perception of acceptable or optimal outcome may be discordant with those described in clinical trials. METHODS: A three-question anonymous voluntary survey was emailed to academic and community practicing neurologists and board-eligible or board-certified neurology fellows inquiring about their personal perception of a better quality of life between two choices featuring clinical scenarios that would qualify as modified Rankin Scale 2 and 4 disability outcome scores. RESULTS: Sixty-nine percent of participants were 30-45 years old, 24% were 45-60 years old, and 7% were over 60 years old. Most responders were general neurologists (31.3%). The remaining responders represented multiple subspecialties including neurocritical care, vascular neurology, neurohospitalist medicine, neuromuscular neurology, neurophysiology, child neurology, neuro-oncology, headache, neuroimmunology, movement disorders, and palliative care medicine. Forty-four of 45 neurologists (97.7%) stated they would choose needing a wheelchair if still able to function at their cognitive baseline at work (p < 0.000001). One responder preferred to get around without assistance, despite new cognitive symptoms that would preclude them from working as a physician. CONCLUSIONS: The modified Rankin Scale may not adequately represent preferred outcomes among neurology specialists, particularly with respect to cognitive symptoms. Future studies are needed to characterize long-term cognitive outcomes in patients with acute stroke-related conditions.

Long-term cognitive impairment after acute respiratory distress syndrome: a review of clinical impact and pathophysiological mechanisms.

Acute respiratory distress syndrome (ARDS) survivors experience a high prevalence of cognitive impairment with concomitantly impaired functional status and quality of life, often persisting months after hospital discharge. In this review, we explore the pathophysiological mechanisms underlying cognitive impairment following ARDS, the interrelations between mechanisms and risk factors, and interventions that may mitigate the risk of cognitive impairment. Risk factors for cognitive decline following ARDS include pre-existing cognitive impairment, neurological injury, delirium, mechanical ventilation, prolonged exposure to sedating medications, sepsis, systemic inflammation, and environmental factors in the intensive care unit, which can co-occur synergistically in various combinations. Detection and characterization of pre-existing cognitive impairment imparts challenges in clinical management and longitudinal outcome study enrollment. Patients with brain injury who experience ARDS constitute a distinct population with a particular combination of risk factors and pathophysiological mechanisms: considerations raised by brain injury include neurogenic pulmonary edema, differences in sympathetic activation and cholinergic transmission, effects of positive end-expiratory pressure on cerebral microcirculation and intracranial pressure, and sensitivity to vasopressor use and volume status. The blood-brain barrier represents a physiological interface at which multiple mechanisms of cognitive impairment interact, as acute blood-brain barrier weakening from mechanical ventilation and systemic inflammation can compound existing chronic blood-brain barrier dysfunction from Alzheimer's-type pathophysiology, rendering the brain vulnerable to both amyloid-beta accumulation and cytokine-mediated hippocampal damage. Although some contributory elements, such as the presenting brain injury or pre-existing cognitive impairment, may be irreversible, interventions such as minimizing mechanical ventilation tidal volume, minimizing duration of exposure to sedating medications, maintaining hemodynamic stability, optimizing fluid balance, and implementing bundles to enhance patient care help dramatically to reduce duration of delirium and may help prevent acquisition of long-term cognitive impairment.

Acute neuropathological consequences of short-term mechanical ventilation in wild-type and Alzheimer's disease mice.

BACKGROUND: Mechanical ventilation is strongly associated with cognitive decline after critical illness. This finding is particularly evident among older individuals who have pre-existing cognitive impairment, most commonly characterized by varying degrees of cerebral amyloid-ß accumulation, neuroinflammation, and blood-brain barrier dysfunction. We sought to test the hypothesis that short-term mechanical ventilation contributes to the neuropathology of cognitive impairment by (i) increasing cerebral amyloid-ß accumulation in mice with pre-existing Alzheimer's disease pathology, (ii) increasing neurologic and systemic inflammation in wild-type mice and mice with pre-existing Alzheimer's disease pathology, and (iii) increasing hippocampal blood-brain barrier permeability in wild-type mice and mice with pre-existing Alzheimer's disease pathology. METHODS: We subjected double transgenic Alzheimer's disease (APP/PSEN1) and wild-type mice to mechanical ventilation for 4 h and compared to non-mechanically ventilated Alzheimer's disease model and wild-type mice. Cerebral soluble/insoluble amyloid-ß1-40/amyloid-ß1-42 and neurological and systemic markers of inflammation were quantified. Hippocampal blood-brain barrier permeability was quantified using a novel methodology that enabled assessment of small and large molecule permeability across the blood-brain barrier. RESULTS: Mechanical ventilation resulted in (i) a significant increase in cerebral soluble amyloid-ß1-40 (p = 0.007) and (ii) significant increases in neuroinflammatory cytokines in both wild-type and Alzheimer's disease mice which, in most cases, were not reflected in the plasma. There were (i) direct correlations between polymorphonuclear cells in the bronchoalveolar fluid and cerebral soluble amyloid-ß1-40 (p = 0.0033), and several Alzheimer's disease-relevant neuroinflammatory biomarkers including cerebral TNF-α and IL-6; (iii) significant decreases in blood-brain barrier permeability in mechanically ventilated Alzheimer's disease mice and a trend towards increased blood-brain barrier permeability in mechanically ventilated wild-type mice. CONCLUSIONS: These results provide the first evidence that short-term mechanical ventilation independently promotes the neuropathology of Alzheimer's disease in subjects with and without pre-existing cerebral Alzheimer's disease pathology. Future studies are needed to further clarify the specific mechanisms by which this occurs and to develop neuroprotective mechanical ventilation strategies that mitigate the risk of cognitive decline after critical illness.

Prognostication of long-term outcomes after subarachnoid hemorrhage: The FRESH score.

OBJECTIVE: To create a multidimensional tool to prognosticate long-term functional, cognitive, and quality of life outcomes after spontaneous subarachnoid hemorrhage (SAH) using data up to 48 hours after admission. METHODS: Data were prospectively collected for 1,619 consecutive patients enrolled in the SAH outcome project July 1996 to March 2014. Linear models (LMs) were applied to identify factors associated with outcome in 1,526 patients with complete data. Twelve-month functional, cognitive, and quality of life outcomes were measured using the modified Rankin scale (mRS), Telephone Interview for Cognitive Status, and Sickness Impact Profile. Based on the LM residuals, we constructed the FRESH score (Functional Recovery Expected after Subarachnoid Hemorrhage). Score performance, discrimination, and internal validity were tested using the area under the receiver operating characteristic curve (AUC), Nagelkerke and Cox/Snell R(2) , and bootstrapping. For external validation, we used a control population of SAH patients from the CONSCIOUS-1 study (n = 413). RESULTS: The FRESH score was composed of Hunt & Hess and APACHE-II physiologic scores on admission, age, and aneurysmal rebleed within 48 hours. Separate scores to prognosticate 1-year cognition (FRESH-cog) and quality of life (FRESH-quol) were developed controlling for education and premorbid disability. Poor functional outcome (mRS = 4-6) for score levels 1 through 9 respectively was present in 3, 6, 12, 38, 61, 83, 92, 98, and 100% at 1-year follow-up. Performance of FRESH (AUC = 0.90), FRESH-cog (AUC = 0.80), and FRESH-quol (AUC = 0.78) was high. External validation of our cohort using mRS as endpoint showed satisfactory results (AUC = 0.77). To allow for convenient score calculation, we built a smartphone app available for free download. INTERPRETATION: FRESH is the first clinical tool to prognosticate long-term outcome after spontaneous SAH in a multidimensional manner. Ann Neurol 2016;80:46-58.

Optimizing Outcomes for Mechanically Ventilated Patients in an Era of Endovascular Acute Ischemic Stroke Therapy.

Endovascular mechanical thrombectomy is a new standard of care for acute ischemic stroke (AIS). The majority of these patients receive mechanical ventilation (MV), which has been associated with poor outcomes. The implication of this is significant, as most neurointerventionalists prefer general compared to local anesthesia during the procedure. Consequences of hemodynamic and respiratory perturbations during general anesthesia and MV are thought to contribute significantly to the poor outcomes that are encountered. In this review, we first describe the unique risks associated with MV in the specific context of AIS and then discuss evidence of brain goal-directed approaches that may mitigate these risks. These strategies include an individualized approach to hemodynamic parameters (eg, adherence to a minimum blood pressure goal and adequate volume resuscitation), respiratory parameters (eg, arterial carbon dioxide optimization), and the use of ventilator settings that optimize neurological outcomes (eg, arterial oxygen optimization).

Systematic Quality Assessment of Published Antishivering Protocols.

Shivering is a common side effect of targeted temperature modulation and general anesthesia. Antishivering strategies often employ a stepwise approach involving both pharmacological and physical interventions. However, approaches to treat shivering are often empiric and vary widely across care environments. We evaluated the quality of published antishivering protocols and guidelines with respect to methodological rigor, reliability, and consistency of recommendations.Using 4 medical databases, we identified 4027 publications that addressed shivering therapy, and excluded 3354 due to lack of relevance. After applying predefined eligibility criteria with respect to minimal protocol standards, 18 protocols/guidelines remained. Each was assessed using a modified Appraisal of Guidelines for Research and Evaluation II (mAGREE II) instrument containing 23 quality items within 6 domains (maximal score 23). Among 18 protocols/guidelines, only 3 incorporated systematically reviewed recommendations, whereas 15 merely targeted practice standardization. Fifteen of 18 protocols/guidelines addressed shivering during therapeutic cooling in which skin counterwarming and meperidine were most commonly cited. However, their mAGREE II scores were within the lowest tertile (1 to 7 points) and the median for all 18 protocols was 5. The quality domains most commonly absent were stakeholder involvement, rigor of development, and editorial independence. Three of 18 protocols/guidelines addressed postanesthetic antishivering. Of these, the American Society of Anesthesiologists guidelines recommending forced-air warming and meperidine received the highest mAGREE II score (14 points), whereas the remaining 2 recommendations had low scores (<5 points).Current published antishivering protocols/guidelines lack methodological rigor, reliability, and strength, and even the highest scoring of the 18 protocols/guidelines fulfilled only 60% of quality items. To be consistent with evidence-based protocol/guideline development processes, future antishivering treatment algorithms should increase methodological rigor and transparency.

Transcranial Doppler Changes in Patients Treated with Extracorporeal Membrane Oxygenation.

BACKGROUND: Transcranial Doppler (TCD) has significant implications for neurovascular assessment in patients being treated with venoarterial-extracorporeal membrane oxygenation (VA-ECMO). However, there have been no studies demonstrating the changes in pulsatility indices (PIs) seen in these patients. Nonpulsatile waveforms are seen during on-pump coronary artery bypass graft, but low or low-normal PIs have never been reported. It is important to be aware of these changes, as they can be misinterpreted as cerebral vasodilation, vasoconstriction, increased intracranial pressures (ICPs), or cerebral circulatory arrest. METHODS: Data from 11 TCDs from 8 patients on VA-ECMO in the Cedars Sinai Medical Center Cardiac Surgical Intensive Care Unit were reviewed. Mean pulsatility indices were calculated for each patient using Gosling's PI formula. The values obtained were correlated with ejection fraction (EF) values obtained from a transthoracic or transesophageal echocardiogram. RESULTS: PIs were globally low or absent in all 11 TCDs. In 3 patients, TCDs were performed at the initiation and conclusion of the VA-ECMO cannulation. The PI values for these TCDs correlated directly with changes in EFs. Also, an abrupt rise in PI to normal value was seen with the placement of a total artificial heart and the return of pulsatile circulation. CONCLUSIONS: We demonstrate that PIs on TCDs in patients treated with VA-ECMO are either low or cannot be calculated depending on the severity of myocardial suppression, and should not be mistaken for cerebral vasodilation or cerebral circulatory arrest. Moreover, rising PIs in these patients can represent improving cardiac function and should not be confused with elevated ICPs.

Hospital Readmission Rates Among Mechanically Ventilated Patients With Stroke.

BACKGROUND AND PURPOSE: Tracheostomy is frequently performed in patients with severe ischemic stroke, intracerebral hemorrhage, or subarachnoid hemorrhage. Little is known about readmission rates among stroke patients who undergo mechanical ventilation. METHODS: We used previously validated International Classification of Diseases, Ninth Edition-Clinical Modification codes and data on all discharges from nonfederal acute care hospitals in 3 states. We compared readmission rates among mechanically ventilated patients with stroke who were discharged with or without a tracheostomy. RESULTS: Among 39,881 patients who underwent mechanical ventilation during the index stroke hospitalization and survived to discharge, 10,690 (26.8%; 95% confidence interval, 26.4%-27.2%) underwent tracheostomy. During a mean follow-up period of 3.4 (±2.0) years, the overall incidence rate of readmissions was 4.25 (95% confidence interval, 4.22-4.28) per 100 patients per 30 days. The rate of any readmissions within 30 days was 26.9% among patients with tracheostomy compared with 22.5% among those without a tracheostomy (absolute risk difference, 4.4%; 95% confidence interval, 3.5%-5.4%; P<0.001). After adjustment for potentially confounding variables, tracheostomy was associated with a slightly increased readmission rate (incidence rate ratio, 1.07; 95% confidence interval, 1.03-1.11). CONCLUSIONS: Approximately one quarter of mechanically ventilated patients with stroke who survive to discharge are readmitted to the hospital within 30 days. Readmission rates are significantly higher in patients with stroke who undergo tracheostomy, but the difference is not clinically meaningful. Thirty-day readmission rates among mechanically ventilated patients with stroke are similar to Medicare beneficiaries hospitalized with major medical diseases such as pneumonia.

Periodic Epileptiform Discharges Clarified for the Nonneurologist Intensivist: Clinical Implications and Current Management.

Periodic epileptiform discharges (PEDs) are frequently encountered during continuous electroencephalography monitoring in the intensive care unit. Their implications and management are variable and highly dependent on the clinical context. This article is intended for the nonneurologist intensivist, reviews basic terminology and clinical implications (including causes, prognosis, and association with seizures), and suggests an approach to management. Several case vignettes are included to illustrate the clinical variability associated with PEDs.

Mechanical Ventilation for Acute Stroke: A Multi-state Population-Based Study.

BACKGROUND: Mechanical ventilation is frequently performed in patients with ischemic stroke (IS), intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH). In this study, we used statewide administrative claims data to examine the rates of use, associated conditions, and in-hospital mortality rates for mechanically ventilated stroke patients. METHODS: We used statewide administrative claims data from three states and ICD-9-CM codes to identify patients admitted with stroke and those who received mechanical ventilation and tracheostomy. Descriptive statistics and exact 95 % confidence intervals were used to report rates of mechanical ventilation, tracheostomy, and in-hospital mortality. Logistic regression analysis was performed to identify conditions associated with mechanical ventilation based on previously described risk factors. RESULTS: 798,255 hospital admissions for stroke were identified. 12.5 % of these patients underwent mechanical ventilation. This rate varied by stroke type: 7.9 % for IS, 29.9 % for ICH, and 38.5 % for SAH. Increased age was associated with a decreased risk of receiving mechanical ventilation (RR per decade, 0.91). Of stroke patients who underwent mechanical ventilation, 16.3 % received a tracheostomy. Mechanical ventilation was more likely to occur in association with status epilepticus (RR, 5.1), pneumonia (RR, 4.9), sepsis (RR, 3.6), and hydrocephalus (RR, 3.3). In-hospital mortality rate for mechanically ventilated stroke patients was 52.7 % (46.8 % for IS, 61.0 % for ICH, and 54.6 % for SAH). CONCLUSIONS: In this large population-based sample, over half of mechanically ventilated stroke patients died in the hospital despite the fact that younger patients were more likely to receive mechanical ventilation. Future studies are indicated to elucidate mechanical ventilation strategies to optimize long-term outcomes after severe stroke.

Reducing low-value interhospital transfers for mild traumatic brain injury.

BACKGROUND: The modified Brain Injury Guidelines (mBIG) were developed to stratify traumatic brain injuries (TBIs) and improve health care utilization by selectively requiring repeat imaging, intensive care unit admission, and neurosurgical (NSG) consultation. The goal of this study is to assess safety and potential resource savings associated with the application of mBIG on interhospital patient transfers for TBI. METHODS: Adult patients with TBI transferred to our Level I trauma center from January 2017 to December 2022 meeting mBIG inclusion criteria were retrospectively stratified into mBIG1, mBIG2, and mBIG3 based on initial clinicoradiological factors. At the time, our institution routinely admitted patients with TBI and intracranial hemorrhage (ICH) to the intensive care unit and obtained a repeat head computed tomography with NSG consultation, independent of TBI severity or changes in neurological examination. The primary outcome was progression of ICH on repeat imaging and/or NSG intervention. Secondary outcomes included length of stay and financial charges. Subgroup analysis on isolated TBI without significant extracranial injury was performed. RESULTS: Over the 6-year study period, 289 patients were classified into mBIG1 (61; 21.1%), mBIG2 (69; 23.9%), and mBIG3 (159; 55.0%). Of mBIG1 patients, 2 (2.9%) had radiological progression to mBIG2 without clinical decline, and none required NSG intervention. Of mBIG2, 2 patients (3.3%) progressed to mBIG3, and both required NSG intervention. More than 35% of transferred patients had minor isolated TBI. For mBIG1 and mBIG2, the median hospitalization charges per patient were $152,296 and $149,550, respectively, and the median length of stay was 4 and 5 days, respectively, with the majority downgraded from the intensive care unit within 48 hours. CONCLUSION: Clinically significant progression of ICH occurred infrequently in 1.5% of patients with mBIG1 and mBIG2 injuries. More than 35% of interfacility transfers for minor isolated TBI meeting mBIG1 and 2 criteria are low value and may potentially be safely deferred in an urban health care setting. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level IV.

Tocilizumab is associated with reduced delirium and coma in critically ill patients with COVID-19.

Recent preclinical studies demonstrate a direct pathological role for the interleukin-6 (IL-6) pathway in mediating structural and functional delirium-like phenotypes in animal models of acute lung injury. Tocilizumab, an IL-6 pathway inhibitor, has shown reduced duration of ventilator dependency and mortality in critically ill patients with COVID-19. In this study, we test the hypothesis that tocilizumab is associated with reduced delirium/coma prevalence in critically ill patients with COVID-19. 253 patients were included in the study cohort, 69 in the tocilizumab group and 184 in the historical control group who did not receive tocilizumab. Delirium was assessed using the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) with a positive score indicating delirium. Coma was defined as a Richmond Agitation-Sedation Scale score of - 4 or - 5. Tocilizumab was associated with significantly greater number of days alive without delirium/coma (tocilizumab [7 days (IQR: 3-9 days)] vs control [3 days (IQR: 1-8 days)]; p < 0.001). These results remained significant after adjusting for age, sex, sepsis, Charlson Comorbidity Index, Sequential Organ Failure Assessment score, and median daily dose of analgesics/sedatives ( ß ^ = 0.671, p = 0.010). There were no significant differences in mortality ( ß ^ = - 0.204, p = 0.561), ventilator duration ( ß ^ = 0.016, p = 0.956), and ICU or hospital length of stay ( ß ^ = - 0.134, p = 0.603; ß ^ = 0.003, p = 0.991, respectively). Tocilizumab use was associated with significantly increased number of days without delirium/coma. Confirmation of these findings in randomized prospective studies may inform a novel paradigm of pharmacological amelioration of delirium/coma during critical illness.

Alzheimer's disease pathophysiology in the Retina.

The retina is an emerging CNS target for potential noninvasive diagnosis and tracking of Alzheimer's disease (AD). Studies have identified the pathological hallmarks of AD, including amyloid ß-protein (Aß) deposits and abnormal tau protein isoforms, in the retinas of AD patients and animal models. Moreover, structural and functional vascular abnormalities such as reduced blood flow, vascular Aß deposition, and blood-retinal barrier damage, along with inflammation and neurodegeneration, have been described in retinas of patients with mild cognitive impairment and AD dementia. Histological, biochemical, and clinical studies have demonstrated that the nature and severity of AD pathologies in the retina and brain correspond. Proteomics analysis revealed a similar pattern of dysregulated proteins and biological pathways in the retina and brain of AD patients, with enhanced inflammatory and neurodegenerative processes, impaired oxidative-phosphorylation, and mitochondrial dysfunction. Notably, investigational imaging technologies can now detect AD-specific amyloid deposits, as well as vasculopathy and neurodegeneration in the retina of living AD patients, suggesting alterations at different disease stages and links to brain pathology. Current and exploratory ophthalmic imaging modalities, such as optical coherence tomography (OCT), OCT-angiography, confocal scanning laser ophthalmoscopy, and hyperspectral imaging, may offer promise in the clinical assessment of AD. However, further research is needed to deepen our understanding of AD's impact on the retina and its progression. To advance this field, future studies require replication in larger and diverse cohorts with confirmed AD biomarkers and standardized retinal imaging techniques. This will validate potential retinal biomarkers for AD, aiding in early screening and monitoring.

Pearls & Oy-sters: Status Epilepticus and Cerebral Edema From Hyperammonemia Due to Disseminated Ureaplasma and Mycoplasma Species.

Nonhepatic hyperammonemia syndrome is a rare cause of neurologic dysfunction and cerebral edema and has most commonly been reported in posttransplant patients. Only recently has opportunistic infection with Ureaplasma species and Mycoplasma hominis been found to be key to the pathogenesis. We describe the cases of 3 immunosuppressed patients who developed hyperammonemia syndrome with new-onset refractory status epilepticus and diffuse cerebral edema. PCR was positive for M hominis in 1 patient and Ureaplasma parvum in the other 2. Despite early diagnostic suspicion and aggressive management with empirical antibiotics, seizure control, hypertonic saline, and ammonia elimination, none of our patients survived this life-threatening infection. Nonhepatic hyperammonemia and new-onset seizures can be presenting features of disseminated Ureaplasma species and M hominis infections in posttransplant patients. Immunosuppression in the absence of organ transplantation is likely sufficient to trigger this entity, as was the case in our third patient. When suspected, empiric combination antibiotics should be used due to high likelihood of resistance. The diagnostic test of choice is PCR. Patients with hyperammonemia syndrome associated with these infections typically have a poor prognosis. Early recognition and aggressive multimodal interventions may be key to ameliorating the high mortality and severe neurologic sequelae from this entity.