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Abstract Despite the longstanding use of nitrous oxide and descriptions of its psychological effects more than a century ago, there is a paucity of neurobiological investigation of associated psychedelic experiences. We measure the brain’s functional geometry (through analysis of cortical gradients) and temporal dynamics (through analysis of co-activation patterns) using human resting-state functional magnetic resonance imaging data acquired before and during administration of 35% nitrous oxide. Both analyses demonstrate that nitrous oxide reduces functional differentiation in frontoparietal and somatomotor networks. Importantly, the subjective psychedelic experience induced by nitrous oxide is inversely correlated with the degree of functional differentiation. Thus, like classical psychedelics acting on serotonin receptors, nitrous oxide flattens the functional geometry of the cortex and disrupts temporal dynamics in association with psychoactive effects.

Abstract Background Delirium in hospitalized patients is a major public health issue, yet delirium is often unrecognized and missed during inpatient admission. The objective of this study was to identify barriers to delirium screening, identification, and management from a nursing perspective on inpatient, acute care units. Methods This was a pre-implementation, diagnostic evaluation study to determine current practice patterns and potential barriers to optimizing delirium care at a major university hospital. A qualitative approach was used, which included focus groups of inpatient nurses working on major medical and surgical acute care units. Focus groups were conducted until signs of thematic saturation were present, and data were analyzed via inductive thematic analysis, without predetermined theories or structures. A consensus approach was utilized for transcript coding, and final themes were generated after multiple reviews of initial themes against transcript datasets. Results Focus group sessions (n = 3) were held with 18 nurses across two major inpatient units. Nurses reported several barriers to successful delirium screening and management. Specific challenges included difficulty with using delirium screening tools, an organizational culture not conducive to delirium prevention, and competing clinical priorities. Proposed solutions were also discussed, including decision-support systems with automated pager alerts and associated delirium order sets, which may help improve delirium care coordination and standardization. Conclusion At a major university hospital, nurses affirm the difficulty experienced with delirium screening and identification, particularly due to screening tool challenges, cultural barriers, and clinical workload. These impediments may serve as targets for a future implementation trial to improve delirium screening and management.

The neurobiology of the psychedelic experience is not fully understood. Identifying common brain network changes induced by both classical (i.e., acting at the 5-HT2 receptor) and non-classical psychedelics would provide mechanistic insight into state-specific characteristics. We analyzed whole-brain functional connectivity based on resting-state fMRI data in humans, acquired before and during the administration of nitrous oxide, ketamine, and lysergic acid diethylamide. We report that, despite distinct molecular mechanisms and modes of delivery, all three psychedelics reduced within-network functional connectivity and enhanced between-network functional connectivity. More specifically, all three drugs increased connectivity between right temporoparietal junction and bilateral intraparietal sulcus as well as between precuneus and left intraparietal sulcus. These regions fall within the posterior cortical “hot zone,” posited to mediate the qualitative aspects of experience. Thus, both classical and non-classical psychedelics modulate networks within an area of known relevance for consciousness, identifying a biologically plausible candidate for their subjective effects.

Introduction Delirium is a major public health issue for surgical patients and their families because it is associated with increased mortality, cognitive and functional decline, prolonged hospital admission and increased healthcare expenditures. Based on preliminary data, this trial tests the hypothesis that intravenous caffeine, given postoperatively, will reduce the incidence of delirium in older adults after major non-cardiac surgery.Methods and analysis The CAffeine, Postoperative Delirium And CHange In Outcomes after Surgery-2 (CAPACHINOS-2) Trial is a single-centre, placebo-controlled, randomised clinical trial that will be conducted at Michigan Medicine. The trial will be quadruple-blinded, with clinicians, researchers, participants and analysts all masked to the intervention. The goal is to enrol 250 patients with a 1:1:1: allocation ratio: dextrose 5% in water placebo, caffeine 1.5 mg/kg and caffeine 3 mg/kg as a caffeine citrate infusion. The study drug will be administered intravenously during surgical closure and on the first two postoperative mornings. The primary outcome will be delirium, assessed via long-form Confusion Assessment Method. Secondary outcomes will include delirium severity, delirium duration, patient-reported outcomes and opioid consumption patterns. A substudy analysis will also be conducted with high-density electroencephalography (72-channel system) to identify neural abnormalities associated with delirium and Mild Cognitive Impairment at preoperative baseline.Ethics and dissemination This study was approved by the University of Michigan Medical School Institutional Review Board (HUM00218290). An independent data and safety monitoring board has also been empanelled and has approved the clinical trial protocol and related documents. Trial methodology and results will be disseminated via clinical and scientific journals along with social and news media.Trial registration number NCT05574400.

Canine infectious respiratory disease complex (CIRDC) is caused by different viruses and bacteria. Viruses associated with CIRDC include canine adenovirus type 2 (CAV-2), canine distemper virus (CDV), canine influenza virus (CIV), canine herpesvirus type 1 (CHV-1), canine respiratory coronavirus (CRCoV), and canine parainfluenza virus (CPIV). Bacteria associated with CIRDC include Bordetella bronchiseptica, Streptococcus equi subspecies zooepidemicus (S. zooepidemicus), and Mycoplasma spp. The present study examined the prevalence of CIRDC pathogens in specimens received by a Veterinary Diagnostic Laboratory in Georgia, USA., from 2018 to 2022. Out of 459 cases, viral agents were detected in 34% of cases and bacterial agents were detected in 58% of cases. A single pathogen was detected in 31% of cases, while two or more pathogens were identified in 24% of cases. The percentages of viral agents identified were CAV-2 (4%), CDV (3%), CPIV (16%), CRCoV (7%), and CIV (2%). The percentages of bacterial agents were B. bronchiseptica (10%), Mycoplasma canis (24%), Mycoplasma cynos (21%), and S. zooepidemicus (2%). Over the five-year period, the positive cases ranged from 2–4% for CAV-2, 1–7% for CDV, 1–4% for CHV-1, 9–22% for CPIV, 4–13% for CRCoV, and 1–4% for CIV. Overall, the most prevalent pathogens associated with CIRDC were CPIV, M. canis, and M. cynos.

Delirium is a major public health issue associated with considerable morbidity and mortality, particularly after surgery. While the neurobiology of delirium remains incompletely understood, emerging evidence suggests that cognition requires close proximity to a system state called criticality, which reflects a point of dynamic instability that allows for flexible access to a wide range of brain states. Deviations from criticality are associated with neurocognitive disorders, though the relationship between criticality and delirium has not been formally tested. This study tested the primary hypothesis that delirium in the postanesthesia care unit would be associated with deviations from criticality, based on surrogate electroencephalographic measures. As a secondary objective, the impact of caffeine was also tested on delirium incidence and criticality. To address these aims, we conducted a secondary analysis of a randomized clinical trial that tested the effects of intraoperative caffeine on postoperative recovery in adults undergoing major surgery. In this substudy, whole-scalp (16-channel) electroencephalographic data were analyzed from a subset of trial participants (n = 55) to determine whether surrogate measures of neural criticality – (1) autocorrelation function of global alpha oscillations and (2) topography of phase relationships via phase lag entropy – were associated with delirium. These measures were analyzed in participants experiencing delirium in the postanesthesia care unit (compared to those without delirium) and in participants randomized to caffeine compared to placebo. Results demonstrated that autocorrelation function in the alpha band was significantly reduced in delirious participants, which is important given that alpha rhythms are postulated to play a vital role in consciousness. Moreover, participants randomized to caffeine demonstrated increased alpha autocorrelation function concurrent with reduced delirium incidence. Lastly, the anterior-posterior topography of phase relationships appeared most preserved in non-delirious participants and in those receiving caffeine. These data suggest that early postoperative delirium may reflect deviations from neural criticality, and caffeine may reduce delirium risk by shifting cortical dynamics toward criticality.

Background: Delirium is a common and serious complication of major surgery for older adults. Postoperative social and behavioral support (e.g., early mobilization, mealtime assistance) may reduce the incidence and impact of delirium, and these efforts are possible with proactive patient-care programs. This pilot trial tests the hypothesis that a multicomponent decision support system, which sends automated alerts and recommendations to patient-care programs and family members for high-risk patients, will improve the postoperative environment for neurocognitive and clinical recovery. Methods: This will be a randomized, controlled, factorial pilot trial at a large academic medical center. High-risk, non-cardiac surgery patients (≥70 years old) will be recruited. Patients will be allocated to a usual care group (n=15), Hospital Elder Life Program (HELP)-based paging system (n=15), family-based paging system (n=15), or combined HELP- and family-based system (n=15). The primary outcome will be the presence of delirium, defined by positive long-form Confusion Assessment Method screening. Secondary outcomes will include additional HELP- and family-based performance metrics along with various neurocognitive and clinical recovery measures. Exploratory outcomes include the incidence of positive family-based delirium assessments post-discharge, 36-item Short Form Survey, PROMIS Cognitive Function Abilities Subset 4a, and 30-day readmission rates. Ethics and dissemination: This trial has received approval by the University of Michigan Medical Institutional Review Board (IRBMED). Dissemination plans include presentation at scientific conferences, publication in medical journals, and distribution via educational and news media. Registration: ClinicalTrials.gov Identifier NCT04007523, registered on 7/3/2019.

An advanced understanding of the neurophysiologic changes that occur with aging may help improve care for older, vulnerable surgical patients. The objective of this study was to determine age-related changes in cortical connectivity patterns during surgical anesthesia. This was a substudy analysis of a prospective, observational study characterizing cortical connectivity during surgical anesthesia in adult patients (n = 45) via whole-scalp (16-channel) electroencephalography. Functional connectivity was estimated using a weighted phase lag index (wPLI), which was classified into a discrete set of states through k-means analysis. Temporal dynamics were quantified by occurrence rate and state transition probabilities. The mean global connectivity state transition probability [13.4% (±8.1)] was not correlated with age (ρ = 0.100, p = 0.513). Increasing age was inversely correlated with prefrontal-frontal alpha-beta connectivity (ρ = −0.446, p = 0.002) and positively correlated with frontal-parietal theta connectivity (ρ = 0.414, p = 0.005). After adjusting for anesthetic-related confounders, prefrontal-frontal alpha-beta connectivity remained significantly associated with age (β = −0.625, 95% CI −0.99 to −0.26; p = 0.001), while frontal-parietal theta connectivity was no longer significant (β = 0.436, 95% CI −0.03 to 0.90; p = 0.066). Specific transition states were also examined. Between frontal-parietal connectivity states, transitioning from theta-alpha to theta-dominated connectivity positively correlated with age (ρ = 0.545, p = 0.001). Dynamic connectivity states during surgical anesthesia, particularly involving alpha and theta bandwidths, maybe an informative measure to assess neurophysiologic changes that occur with aging.

Background: Stroke is a devastating perioperative complication without effective methods for prevention or diagnosis. The objective of this study was to analyze evidence-based strategies for detecting cerebrovascular vulnerability and injury in a high-risk cohort of non-cardiac surgery patients.Methods: This was a single-center, prospective cohort study. Fifty patients undergoing non-cardiac surgery were recruited −25 with known cerebrovascular disease and 25 matched controls. Neurologic vulnerability was measured with intraoperative cerebral oximetry as the primary outcome. Perioperative neurocognitive testing and serum biomarker analysis (S-100β, neuron specific enolase, glial fibrillary acid protein, and matrix metalloproteinase-9) were measured as secondary outcomes.Results: Cerebral desaturation events (an oximetry decrease ≥20% from baseline or

Background: Delirium is a common and serious complication of major surgery for older adults. Postoperative social and behavioral support (e.g., early mobilization, mealtime assistance) may reduce the incidence and impact of delirium, and these efforts are possible with proactive patient-care programs. This pilot trial tests the hypothesis that a multicomponent decision support system, which sends automated alerts and recommendations to patient-care programs and family members for high-risk patients, will improve the postoperative environment for neurocognitive and clinical recovery. Methods: This will be a randomized, controlled, factorial pilot trial at a large academic medical center. High-risk, non-cardiac surgery patients (≥70 years old) will be recruited. Patients will be allocated to a usual care group (n=15), Hospital Elder Life Program (HELP)-based paging system (n=15), family-based paging system (n=15), or combined HELP- and family-based system (n=15). The primary outcome will be the presence of delirium, defined by positive long-form Confusion Assessment Method screening. Secondary outcomes will include additional HELP- and family-based performance metrics along with various neurocognitive and clinical recovery measures. Exploratory outcomes include the incidence of positive family-based delirium assessments post-discharge, 36-item Short Form Survey, PROMIS Cognitive Function Abilities Subset 4a, and 30-day readmission rates. Ethics and dissemination: This trial has received approval by the University of Michigan Medical Institutional Review Board (IRBMED). Dissemination plans include presentation at scientific conferences, publication in medical journals, and distribution via educational and news media. Registration: ClinicalTrials.gov Identifier NCT04007523, registered on 7/3/2019.