Detecting Cerebral Ischemia From Electroencephalography During Carotid Endarterectomy Using Machine Learning.

Monitoring cerebral neuronal activity via electroencephalography (EEG) during surgery can detect ischemia, a precursor to stroke. However, current neurophysiologist-based monitoring is prone to error. In this study, we evaluated machine learning (ML) for efficient and accurate ischemia detection. We trained supervised ML models on a dataset of 802 patients with intraoperative ischemia labels and evaluated them on an independent validation dataset of 30 patients with refined labels from five neurophysiologists. Our results show moderate-to-substantial agreement between neurophysiologists, with Cohen's kappa values between 0.59 and 0.74. Neurophysiologist performance ranged from 58-93% for sensitivity and 83-96% for specificity, while ML models demonstrated comparable ranges of 63-89% and 85-96%. Random Forest (RF), LightGBM (LGBM), and XGBoost RF achieved area under the receiver operating characteristic curve (AUROC) values of 0.92-0.93 and area under the precision-recall curve (AUPRC) values of 0.79-0.83. ML has the potential to improve intraoperative monitoring, enhancing patient safety and reducing costs.

Time-Series Aware Metrics for the Evaluation of Intraoperative Electroencephalography-Based Ischemia Detection.

Continuous intraoperative monitoring with electroencephalo2 graphy (EEG) is commonly used to detect cerebral ischemia in high-risk surgical procedures such as carotid endarterectomy. Machine learning (ML) models that detect ischemia in real time can form the basis of automated intraoperative EEG monitoring. In this study, we describe and compare two time-series aware precision and recall metrics to the classical precision and recall metrics for evaluating the performance of ML models that detect ischemia. We trained six ML models to detect ischemia in intraoperative EEG and evaluated them with the area under the precision-recall curve (AUPRC) using time-series aware and classical approaches to compute precision and recall. The Support Vector Classification (SVC) model performed the best on the time-series aware metrics, while the Light Gradient Boosting Machine (LGBM) model performed the best on the classical metrics. Visual inspection of the probability outputs of the models alongside the actual ischemic periods revealed that the time-series aware AUPRC selected a model more likely to predict ischemia onset in a timely fashion than the model selected by classical AUPRC.

Limitations of Noninvasive Tests-Based Population-Level Risk Stratification Strategy for Nonalcoholic Fatty Liver Disease.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) are highly prevalent but underdiagnosed. AIMS: We used an electronic health record data network to test a population-level risk stratification strategy using noninvasive tests (NITs) of liver fibrosis. METHODS: Data were obtained from PCORnet® sites in the East, Midwest, Southwest, and Southeast United States from patients aged [Formula: see text] 18 with or without ICD-10-CM diagnosis codes for NAFLD, NASH, and NASH-cirrhosis between 9/1/2017 and 8/31/2020. Average and standard deviations (SD) for Fibrosis-4 index (FIB-4), NAFLD fibrosis score (NFS), and Hepatic Steatosis Index (HSI) were estimated by site for each patient cohort. Sample-wide estimates were calculated as weighted averages across study sites. RESULTS: Of 11,875,959 patients, 0.8% and 0.1% were coded with NAFLD and NASH, respectively. NAFLD diagnosis rates in White, Black, and Hispanic patients were 0.93%, 0.50%, and 1.25%, respectively, and for NASH 0.19%, 0.04%, and 0.16%, respectively. Among undiagnosed patients, insufficient EHR data for estimating NITs ranged from 68% (FIB-4) to 76% (NFS). Predicted prevalence of NAFLD by HSI was 60%, with estimated prevalence of advanced fibrosis of 13% by NFS and 7% by FIB-4. Approximately, 15% and 23% of patients were classified in the intermediate range by FIB-4 and NFS, respectively. Among NAFLD-cirrhosis patients, a third had FIB-4 scores in the low or intermediate range. CONCLUSIONS: We identified several potential barriers to a population-level NIT-based screening strategy. HSI-based NAFLD screening appears unrealistic. Further research is needed to define merits of NFS- versus FIB-4-based strategies, which may identify different high-risk groups.

Ventilatory and Orthostatic Challenges Reveal Biomarkers for Neurocognition in Children and Young Adults With Congenital Central Hypoventilation Syndrome.

BACKGROUND: Children and young adults with congenital central hypoventilation syndrome (CCHS) are at risk of cognitive deficits. They experience autonomic dysfunction and chemoreceptor insensitivity measured during ventilatory and orthostatic challenges, but relationships between these features are undefined. RESEARCH QUESTION: Can a biomarker be identified from physiologic responses to ventilatory and orthostatic challenges that is related to neurocognitive outcomes in CCHS? STUDY DESIGN AND METHODS: This retrospective study included 25 children and young adults with CCHS tested over an inpatient stay. Relationships between physiologic measurements during hypercarbic and hypoxic ventilatory challenges, hypoxic ventilatory challenges, and orthostatic challenges and neurocognitive outcomes (by Wechsler intelligence indexes) were examined. Independent variable inclusion was determined by significant associations in Pearson's analyses. Multivariate linear regressions were used to assess relationships between measured physiologic responses to challenges and neurocognitive scores. RESULTS: Significant relationships were identified between areas of fluid intelligence and measures of oxygen saturation (SpO2) and heart rate (HR) during challenges. Specifically, perceptual reasoning was related to HR (adjusted regression [ß] coefficient, -0.68; 95% CI, 1.24 to -0.12; P = .02) during orthostasis. Working memory was related to change in HR (ß, -1.33; 95% CI, -2.61 to -0.05; P = .042) during the hypoxic ventilatory challenge. Processing speed was related to HR (ß, -1.19; 95% CI, -1.93 to -0.46; P = .003) during orthostasis, to baseline SpO2 (hypercarbic and hypoxic ß, 8.57 [95% CI, 1.63-15.51]; hypoxic ß, 8.37 [95% CI, 3.65-13.11]; P = .002 for both) during the ventilatory challenges, and to intrachallenge SpO2 (ß, 5.89; 95% CI, 0.71-11.07; P = .028) during the hypoxic ventilatory challenge. INTERPRETATION: In children and young adults with CCHS, SpO2 and HR-or change in HR-at rest and as a response to hypoxia and orthostasis are related to cognitive outcomes in domains of known risk, particularly fluid reasoning. These findings can guide additional research on the usefulness of these as biomarkers in understanding the impact of daily physical stressors on neurodevelopment in this high-risk group.

Cerebral Autoregulation during Orthostatic Challenge in Congenital Central Hypoventilation Syndrome.

Rationale: Congenital central hypoventilation syndrome (CCHS) is a rare autonomic disorder with altered regulation of breathing, heart rate (HR), and blood pressure (BP). Aberrant cerebral oxygenation in response to hypercapnia/hypoxia in CCHS raises the concern that altered cerebral autoregulation may contribute to CCHS-related, variably impaired neurodevelopment. Objectives: To evaluate cerebral autoregulation in response to orthostatic challenge in CCHS cases versus controls. Methods: CCHS and age- and sex-matched control subjects were studied with head-up tilt (HUT) testing to induce orthostatic stress. Fifty CCHS and 100 control HUT recordings were included. HR, BP, and cerebral oxygen saturation (regional oxygen saturation) were continuously monitored. The cerebral oximetry index (COx), a real-time measure of cerebral autoregulation based on these measures, was calculated. Measurements and Main Results: HUT resulted in a greater mean BP decrease from baseline in CCHS versus controls (11% vs. 6%; P < 0.05) and a diminished increase in HR in CCHS versus controls (11% vs. 18%; P < 0.01) in the 5 minutes after tilt-up. Despite a similar COx at baseline, orthostatic provocation within 5 minutes of tilt-up caused a 50% greater increase in COx (P < 0.01) and a 29% increase in minutes of impaired autoregulation (P < 0.02) in CCHS versus controls (4.0 vs. 3.1 min). Conclusions: Cerebral autoregulatory mechanisms appear to be intact in CCHS, but the greater hypotension observed in CCHS consequent to orthostatic provocation is associated with greater values of COx/impaired autoregulation when BP is below the lower limits of autoregulation. Effects of repeated orthostatic challenges in everyday living in CCHS necessitate further study to determine their influence on neurodevelopmental disease burden.

Wireless, Skin-Interfaced Devices for Pediatric Critical Care: Application to Continuous, Noninvasive Blood Pressure Monitoring.

Indwelling arterial lines, the clinical gold standard for continuous blood pressure (BP) monitoring in the pediatric intensive care unit (PICU), have significant drawbacks due to their invasive nature, ischemic risk, and impediment to natural body movement. A noninvasive, wireless, and accurate alternative would greatly improve the quality of patient care. Recently introduced classes of wireless, skin-interfaced devices offer capabilities in continuous, precise monitoring of physiologic waveforms and vital signs in pediatric and neonatal patients, but have not yet been employed for continuous tracking of systolic and diastolic BP-critical for guiding clinical decision-making in the PICU. The results presented here focus on materials and mechanics that optimize the system-level properties of these devices to enhance their reliable use in this context, achieving full compatibility with the range of body sizes, skin types, and sterilization schemes typically encountered in the PICU. Systematic analysis of the data from these devices on 23 pediatric patients, yields derived, noninvasive BP values that can be quantitatively validated against direct recordings from arterial lines. The results from this diverse cohort, including those under pharmacological protocols, suggest that wireless, skin-interfaced devices can, in certain circumstances of practical utility, accurately and continuously monitor BP in the PICU patient population.

Kangaroo father care: A pilot feasibility study of physiologic, biologic, and psychosocial measures to capture the effects of father-infant and mother-infant skin-to-skin contact in the Neonatal Intensive Care Unit.

Robust literature supports the positive effects of kangaroo mother care (KMC) on infant physiologic stability and parent-infant bonding in the Neonatal Intensive Care Unit (NICU). Comparatively little is known about kangaroo father care (KFC) in the NICU, and KFC implementation has been limited. Our pilot feasibility study objective was to examine KFC effects on premature infants and fathers as compared to KMC. Parents of preterm NICU infants independently completed a 90-min Kangaroo Care (KC) session on consecutive days. Infant heart rate variability (HRV) and apnea/periodicity measures were compared (pre-KC to KC; KFC to KMC). Additionally, we assessed the feasibility of administering three psychosocial questionnaires to fathers and mothers in the NICU and after discharge. Ten preterm infants completed 20 KC sessions (334/7 -374/7  weeks post-menstrual age). Results demonstrated similar infant physiologic responses between KMC and KFC, including significant differences in measures of HRV (p < .05) between KC and non-KC periods. Eighty-eight percentage of questionnaires administered were completed, supporting the utilization of these instruments in future research of this population. If confirmed, these preliminary results identify an opportunity to objectively assess KFC effects, supporting the development of empirically based KFC programs benefitting NICU families.

Pupillometry measures of autonomic nervous system regulation with advancing age in a healthy pediatric cohort.

PURPOSE: To determine if variables of the pupillary light response mature with age and sex in a healthy pediatric cohort and the utility of pupillometry in assessment among pediatric participants. METHODS: After 1 min in a dark room to establish baseline, pupillometry was performed on 323 healthy, pediatric participants (646 eyes; 2-21 years; 175 females). Variables included initial pupil diameter, pupil diameter after light stimulus, percent pupillary constriction, latency to onset of constriction, average constriction velocity, maximum constriction velocity, average dilation velocity, and time from light stimulus to 75% of the initial pupil diameter. Data analyses employed ANOVAs and non-linear regressions. RESULTS: Analyses of age group differences revealed that participants 12-21 years old had a larger initial pupil diameter and pupil diameter after light stimulus, with males aged 12-18 years demonstrating a larger pupil diameter than all younger participants (ps < 0.05). Participants 12-18 years old had a slower maximum constriction velocity than participants 6-11 years old, with no sex differences (ps < 0.05). Furthermore, males aged 12-18 years old had a smaller percent constriction than males 6-11 years old (ps < 0.05). Regressions revealed that percent constriction and dilation velocity seemed to mature linearly, initial pupil diameter and ending pupil diameter matured quadratically, and the constriction velocity terms matured cubically. CONCLUSIONS: Results revealed maturation of the pupillary light response by age and sex in healthy pediatric participants. Given the value of the pupillary light response as a biomarker, the results provide normative benchmarks for comparison in health and disease, including opiate-exposed and concussion patients.

Prospective cohort study of C-reactive protein as a predictor of clinical events in adults with congenital heart disease: results of the Boston adult congenital heart disease biobank.

Aims: Despite the well-defined association of high-sensitivity hsCRP with cardiovascular outcomes in apparently healthy adults and those with acquired heart disease, the relevance of this inflammatory marker in adults with congenital heart disease (ACHD) remains unclear. We aimed to examine the clinical correlates and prognostic value of high-sensitivity C-reactive protein levels in ACHD. Methods and results: We conducted a prospective cohort study of (n = 707) outpatient ACHD (age 39 ± 14 years, 49% women), enrolled mainly at a referral centre, who had serum hsCRP measured in conjunction with a clinical assessment between 2012 and 2016. We analysed clinical correlates of hsCRP and its association with adverse events including the primary combined outcome of all-cause mortality or non-elective cardiovascular hospitalization. Higher hsCRP was strongly associated with measures of functional status including New York Heart Association class and peak V̇O2, and with comorbidities such as atrial arrhythmia. During average follow-up of 815 ± 536 days, 114 patients (16%) experienced the primary outcome, including 29 deaths. Having elevated hsCRP, in the highest (≥2.98 mg/L) compared with the lower three quartiles, conferred increased risk for the primary outcome [30.5% vs. 11.3%, adjusted hazard ratio (HR) = 2.00, 95% confidence interval (CI) 1.35-2.97; P = 0.0006] and all-cause mortality (11.9% vs. 1.5%, adjusted HR = 4.23, 95% CI 1.87-9.59; P = 0.0006). Elevated hsCRP was associated with adverse outcomes across ACHD subgroups and other patient characteristics. Conclusion: Adults with congenital heart disease with elevated hsCRP have not only worse functional status and exercise capacity, but also greater risk for death or non-elective cardiovascular hospitalization. Further study is warranted to characterize the role of inflammation in the pathophysiology of ACHD.

Effect of hospitalization on gastrointestinal motility and pH in dogs.

OBJECTIVE To determine the effect of hospitalization on gastrointestinal motility and pH in healthy dogs. DESIGN Experimental study. ANIMALS 12 healthy adult dogs. PROCEDURES A wireless motility capsule (WMC) that measured pressure, transit time, and pH within the gastrointestinal tract was administered orally to dogs in 2 phases. In the first phase, dogs received the WMC at the hospital and then returned to their home to follow their daily routine. In the second phase, dogs were hospitalized, housed individually, had abdominal radiography performed daily, and were leash exercised 4 to 6 times/d until the WMC passed in the feces. All dogs received the same diet twice per day in both phases. Data were compared between phases with the Wilcoxon signed rank test. RESULTS Data were collected from 11 dogs; 1 dog was excluded because the WMC failed to exit the stomach. Median gastric emptying time during hospitalization (71.8 hours; range, 10.7 to 163.0 hours) was significantly longer than at home (17.6 hours; range, 9.7 to 80.8 hours). Values of all other gastric, small bowel, and large bowel parameters (motility index, motility pattern, pH, and transit time) were similar between phases. No change in gastric pH was detected over the hospitalization period. High interdog variability was evident for all measured parameters. CONCLUSIONS AND CLINICAL RELEVANCE Hospitalization of dogs may result in a prolonged gastric emptying time, which could adversely affect gastric emptying of meals, transit of orally administered drugs, or assessments of underlying motility disorders.

Evaluation of Electroencephalography Source Localization Algorithms with Multiple Cortical Sources.

BACKGROUND: Source localization algorithms often show multiple active cortical areas as the source of electroencephalography (EEG). Yet, there is little data quantifying the accuracy of these results. In this paper, the performance of current source density source localization algorithms for the detection of multiple cortical sources of EEG data has been characterized. METHODS: EEG data were generated by simulating multiple cortical sources (2-4) with the same strength or two sources with relative strength ratios of 1:1 to 4:1, and adding noise. These data were used to reconstruct the cortical sources using current source density (CSD) algorithms: sLORETA, MNLS, and LORETA using a p-norm with p equal to 1, 1.5 and 2. Precision (percentage of the reconstructed activity corresponding to simulated activity) and Recall (percentage of the simulated sources reconstructed) of each of the CSD algorithms were calculated. RESULTS: While sLORETA has the best performance when only one source is present, when two or more sources are present LORETA with p equal to 1.5 performs better. When the relative strength of one of the sources is decreased, all algorithms have more difficulty reconstructing that source. However, LORETA 1.5 continues to outperform other algorithms. If only the strongest source is of interest sLORETA is recommended, while LORETA with p equal to 1.5 is recommended if two or more of the cortical sources are of interest. These results provide guidance for choosing a CSD algorithm to locate multiple cortical sources of EEG and for interpreting the results of these algorithms.

Intravesical glycosaminoglycans for obstructive feline idiopathic cystitis: a pilot study.

Feline idiopathic cystitis is a common condition, often resulting in repeated episodes of life-threatening urethral obstruction. Defective urinary bladder glycosaminoglycans have been implicated as a causal factor. In this report, a commercially available glycosaminoglycan product was infused into the urinary bladders of cats with urethral obstruction from idiopathic cystitis to study the effect on repeated obstruction. In this randomized, blind, placebo-controlled clinical trial, the therapeutic protocol was well tolerated with no adverse effects. Whereas no glycosaminoglycan-treated cats (n = 9) developed repeated urethral obstruction during the 7 day follow-up period, 3/7 placebo-treated cats developed repeated obstructions. Approaching statistical significance (P = 0.06), these data suggest that further investigation of this new treatment option is warranted.

Optical cochlear implants: evaluation of surgical approach and laser parameters in cats.

Previous research has shown that neural stimulation with infrared radiation (IR) is spatially selective and illustrated the potential of IR in stimulating auditory neurons. The present work demonstrates the application of a miniaturized pulsed IR stimulator for chronic implantation in cats, quantifies its efficacy, and short-term safety in stimulating auditory neurons. IR stimulation of the neurons was achieved using an optical fiber inserted through a cochleostomy drilled in the basal turn of the cat cochlea and was characterized by measuring compound action potentials (CAPs). Neurons were stimulated with IR at various pulse durations, radiant exposures, and pulse repetition rates. Pulse durations as short as 50 mus were successful in evoking CAPs in normal as well as deafened cochleae. Continual stimulation was provided at 200 pulses per second, at 200 mW per pulse, and 100 mus pulse duration. Stable CAP amplitudes were observed for up to 10 h of continual IR stimulation. Combined with histological data, the results suggest that pulsed IR stimulation does not lead to detectable acute tissue damage and validate the stimulation parameters that can be used in future chronic implants based on pulsed IR.

Growth and metabolic characterization of Macrorhabdus ornithogaster.

Macrorhabdus ornithogaster (M. ornithogaster) is an anamorphic ascomycetous yeast found only in the stomach of birds. Infection is often benign but has also been associated with disease in some species of birds under some circumstances. In vitro efforts to grow M. ornithogaster have been largely unsuccessful. In this report, multiple liquid and solid media of varying pH, sugar concentration, and fetal bovine serum (FBS) concentrations, incubated at various temperatures in room air or microaerophilic conditions, were examined for their ability to support the growth of M. ornithogaster, obtained from a budgerigar (Melopsittacus undulatus). Optimum growth conditions were found to be Basal Medium Eagle's, pH 3 to 4, containing 20% FBS, and 5% glucose or sucrose under microaerophilic conditions at 42 degrees C. Using these conditions, M. ornithogaster was repeatedly passaged without loss of viability. Polyclonal isolates of M. ornithogaster consistently assimilated glucose, sucrose, and trehalose. M. ornithogaster did not grow with prolonged exposure to atmospheric oxygen, but growth in microaerophilic conditions was moderately enhanced by preincubation with atmospheric oxygen for 24 hours. An isolate of M. ornithogaster was found to be infective to day-old chickens, reduce their rate of weight gain, and induce a mild to moderate heterophilic inflammation of the isthmus. M. ornithogaster was reisolated from the chicks 7 days after infection, fulfilling Koch's postulates. A 761-bp sequence of 18S rDNA from this isolate was compared to the originally reported M. ornithogaster sequence and was found to be 97% identical.