Predicting Hypoxia Using Machine Learning: Systematic Review.

Background: Hypoxia is an important risk factor and indicator for the declining health of inpatients. Predicting future hypoxic events using machine learning is a prospective area of study to facilitate time-critical interventions to counter patient health deterioration. Objective: This systematic review aims to summarize and compare previous efforts to predict hypoxic events in the hospital setting using machine learning with respect to their methodology, predictive performance, and assessed population. Methods: A systematic literature search was performed using Web of Science, Ovid with Embase and MEDLINE, and Google Scholar. Studies that investigated hypoxia or hypoxemia of hospitalized patients using machine learning models were considered. Risk of bias was assessed using the Prediction Model Risk of Bias Assessment Tool. Results: After screening, a total of 12 papers were eligible for analysis, from which 32 models were extracted. The included studies showed a variety of population, methodology, and outcome definition. Comparability was further limited due to unclear or high risk of bias for most studies (10/12, 83%). The overall predictive performance ranged from moderate to high. Based on classification metrics, deep learning models performed similar to or outperformed conventional machine learning models within the same studies. Models using only prior peripheral oxygen saturation as a clinical variable showed better performance than models based on multiple variables, with most of these studies (2/3, 67%) using a long short-term memory algorithm. Conclusions: Machine learning models provide the potential to accurately predict the occurrence of hypoxic events based on retrospective data. The heterogeneity of the studies and limited generalizability of their results highlight the need for further validation studies to assess their predictive performance.

Thinking outside the box: students positive about visionary elective curricula in medical school.

Objective: Space for personality development as well as for the development of critical, creative and interdisciplinary thinking is rarely found in medical curricula in Germany. To be prepared for the challenges of modern medicine, future physicians need a visionary mindset. The aim of this study is to determine the need for teaching such content among medical students in the context of visionary elective curricula and to examine these with regard to the desired topics and organizational structure. Methods: This is a cross-sectional study with 236 medical students from all semesters of the Ludwig-Maximilians-University Munich. The survey consists of 50 questions and includes single choice, multiple choice, matrix questions, open-ended questions and Likert scales. Responses were examined using descriptive statistics and compared parametrically in sub-aspects. Results: Three-quarters of respondents would like to see curricular content on interdisciplinary interfaces with other disciplines. A suitable framework for this is seen by 87% of the respondents in a visionary elective curriculum. Students would like to see a broad range of specific content such as global health, politics, business, and computer science. The majority of respondents would like to see 1 unit of instruction per week and would participate in an appropriate program. Such an offering would promote creative (53.6%), critical (63.7%), and interdisciplinary thinking (69.0%) and train to become better physicians (87%). Conclusion: Participants in this study are positive toward the introduction of visionary content in medical school. Faculties should build visionary elective curricula according to the graduate profile requirements of the new NKLM 2.0 to make medical education sustainable.

Aquaporin-4 Expression during Toxic and Autoimmune Demyelination.

The water channel protein aquaporin-4 (AQP4) is required for a normal rate of water exchange across the blood-brain interface. Following the discovery that AQP4 is a possible autoantigen in neuromyelitis optica, the function of AQP4 in health and disease has become a research focus. While several studies have addressed the expression and function of AQP4 during inflammatory demyelination, relatively little is known about its expression during non-autoimmune-mediated myelin damage. In this study, we used the toxin-induced demyelination model cuprizone as well as a combination of metabolic and autoimmune myelin injury (i.e., Cup/EAE) to investigate AQP4 pathology. We show that during toxin-induced demyelination, diffuse AQP4 expression increases, while polarized AQP4 expression at the astrocyte endfeet decreases. The diffuse increased expression of AQP4 was verified in chronic-active multiple sclerosis lesions. Around inflammatory brain lesions, AQP4 expression dramatically decreased, especially at sites where peripheral immune cells penetrate the brain parenchyma. Humoral immune responses appear not to be involved in this process since no anti-AQP4 antibodies were detected in the serum of the experimental mice. We provide strong evidence that the diffuse increase in anti-AQP4 staining intensity is due to a metabolic injury to the brain, whereas the focal, perivascular loss of anti-AQP4 immunoreactivity is mediated by peripheral immune cells.

Oligodendrocyte degeneration and concomitant microglia activation directs peripheral immune cells into the forebrain.

Brain-intrinsic degenerative cascades are a proposed factor driving inflammatory lesion formation in multiple sclerosis (MS) patients. We recently showed that encephalitogenic lymphocytes are recruited to the sites of active demyelination induced by cuprizone. Here, we investigated whether cuprizone-induced oligodendrocyte and myelin pathology is sufficient to trigger peripheral immune cell recruitment into the forebrain. We show that early cuprizone-induced white matter lesions display a striking similarity to early MS lesions, i.e., oligodendrocyte degeneration, microglia activation and absence of severe lymphocyte infiltration. Such early cuprizone lesions are sufficient to trigger peripheral immune cell recruitment secondary to subsequent EAE (experimental autoimmune encephalomyelitis) induction. The lesions are characterized by discontinuation of the perivascular glia limitans, focal axonal damage, and perivascular astrocyte pathology. Time course studies showed that the severity of cuprizone-induced lesions positively correlates with the extent of peripheral immune cell recruitment. Furthermore, results of genome-wide array analyses suggest that moesin is integral for early microglia activation in cuprizone and MS lesions. This study underpins the significance of brain-intrinsic degenerative cascades for immune cell recruitment and, in consequence, MS lesion formation.

Combination of cuprizone and experimental autoimmune encephalomyelitis to study inflammatory brain lesion formation and progression.

Brain-intrinsic degenerative cascades are a proposed factor driving inflammatory lesion formation in multiple sclerosis (MS) patients. We recently described a model combining noninflammatory cytodegeneration (via cuprizone) with the classic active experimental autoimmune encephalomyelitis (Cup/EAE model), which exhibits inflammatory forebrain lesions. Here, we describe the histopathological characteristics and progression of these Cup/EAE lesions. We show that inflammatory lesions develop at various topographical sites in the forebrain, including white matter tracts and cortical and subcortical grey matter areas. The lesions are characterized by focal demyelination, discontinuation of the perivascular glia limitans, focal axonal damage, and neutrophil granulocyte extravasation. Transgenic mice with enhanced green fluorescent protein-expressing microglia and red fluorescent protein-expressing monocytes reveal that both myeloid cell populations contribute to forebrain inflammatory infiltrates. EAE-triggered inflammatory cerebellar lesions were augmented in mice pre-intoxicated with cuprizone. Gene expression studies suggest roles of the chemokines Cxcl10, Ccl2, and Ccl3 in inflammatory lesion formation. Finally, follow-up experiments in Cup/EAE mice with chronic disease revealed that forebrain, but not spinal cord, lesions undergo spontaneous reorganization and repair. This study underpins the significance of brain-intrinsic degenerative cascades for immune cell recruitment and, in consequence, MS lesion formation.