Neurocritical care
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Neurocritical care patients are a complex patient population, and to aid clinical decision-making, many models and scoring systems have previously been developed. More recently, techniques from the field of machine learning have been applied to neurocritical care patient data to develop models with high levels of predictive accuracy. However, although these recent models appear clinically promising, their interpretability has often not been considered and they tend to be black box models, making it extremely difficult to understand how the model came to its conclusion. ⋯ Further, the use of interpretable machine learning will be explored, in particular the potential benefits and drawbacks that the techniques may have when applied to neurocritical care data. Finding a solution to the lack of model explanation, transparency, and accountability is important because these issues have the potential to contribute to model trust and clinical acceptance, and, increasingly, regulation is stipulating a right to explanation for decisions made by models and algorithms. To ensure that the prospective gains from sophisticated predictive models to neurocritical care provision can be realized, it is imperative that interpretability of these models is fully considered.
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Meta-analyses show a variable relationship between optic nerve sheath diameter (ONSD) and the presence of raised intracranial pressure (ICP). Because optic nerve sheath (ONS) tissue can be deformed, it is possible that ONSD reflects not only the current ICP but also prior deforming biomechanical exposures. In this post hoc analysis of two published data sets, we characterize ONS Young's modulus (E, mechanical stress per unit of strain) and calculate threshold pressure for plastic deformation. ⋯ Ex vivo, ONS plastic deformation occurs at levels of pressure commonly seen in patients with raised ICP, leading to distortion of the ICP-ONSD relationship. This evidence of plastic deformation may illustrate why meta-analyses fail to identify a single threshold in ONSD associated with the presence of raised ICP. Future studies characterizing time-dependent viscous characteristics of the ONS will help determine the time course of ONS tissue biomechanical behavior.
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Although the placement of an intraventricular catheter remains the gold standard technique for measuring intracranial pressure (ICP), the method has several limitations. Therefore, noninvasive alternatives to ICP (ICPni) measurement are of great interest. The main objective of this study was to compare the correlation and agreement of wave morphology between ICP (standard intraventricular ICP monitoring) and a new ICPni monitor in patients admitted with stroke. The second objective was to estimate the discrimination of the noninvasive method to detect intracranial hypertension. ⋯ The new ICPni wave morphology monitor showed a good agreement with the standard invasive method and an acceptable discriminatory power to detect intracranial hypertension. Clinical trial registration Trial registration: NCT05121155.
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The current terminology of delirium and encephalopathy is open to debate. As with any poorly understood disorder with an unknown mechanism, there is a range of opinions. Attention must be paid to a proliferation of new terms and the ease with which they were introduced. ⋯ Rather than expand the definitions of types of delirium and separate them from encephalopathy, we advocate a definition-encephalopathy with or without characteristics of delirium-with the understanding that agitated patients in a delirium are innately encephalopathic. We subscribe to the prevailing neurologic description of delirium. This would allow sufficient granularity for bedside use and prospective studies.
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Cardiac dysfunction is common in the days after severe traumatic brain injury (TBI) and may contribute to hypotension episodes, leading to worse outcomes. Little is known about cardiac function in the minutes and hours immediately following TBI. By using fluid percussion TBI in a swine model, we aimed to characterize the immediate post injury cardiac function. ⋯ Traumatic brain injury is associated with cardiac dysfunction and increased mortality, however there is still a limited understanding of the hemodynamic and echocardiographic response associated with TBI. In this study we demonstrate the hemodynamic and echocardiographic changes in the early stages of TBI in swine. The authors hope that these results may help better understanding on the management of patients with severe head injury.