Bernoulli's Principle Applied to Brain Fluids: Intracranial Pressure Does Not Drive Cerebral Perfusion or CSF Flow.

In line with the first law of thermodynamics, Bernoulli's principle states that the total energy in a fluid is the same at all points. We applied Bernoulli's principle to understand the relationship between intracranial pressure (ICP) and intracranial fluids. We analyzed simple fluid physics along a tube to describe the interplay between pressure and velocity. Bernoulli's equation demonstrates that a fluid does not flow along a gradient of pressure or velocity; a fluid flows along a gradient of energy from a high-energy region to a low-energy region. A fluid can even flow against a pressure gradient or a velocity gradient. Pressure and velocity represent part of the total energy. Cerebral blood perfusion is not driven by pressure but by energy: the blood flows from high-energy to lower-energy regions. Hydrocephalus is related to increased cerebrospinal fluid (CSF) resistance (i.e., energy transfer) at various points. Identification of the energy transfer within the CSF circuit is important in understanding and treating CSF-related disorders. Bernoulli's principle is not an abstract concept far from clinical practice. We should be aware that pressure is easy to measure, but it does not induce resumption of fluid flow. Even at the bedside, energy is the key to understanding ICP and fluid dynamics.

Characterisation of Supra- and Infratentorial ICP Profiles.

In pathophysiology and clinical practice, the intracranial pressure (ICP) profiles in the supratentorial and infratentorial compartments are unclear. We know that the pressure within the skull is unevenly distributed, with demonstrated ICP gradients. We recorded and characterised the supra- and infratentorial ICP patterns to understand what drives the transtentorial ICP gradient.A 70-year-old man was operated on for acute cerebellar infarction. One supratentorial probe and one cerebellar probe were implanted. Both signals were recorded concurrently and analysed off-line. We calculated mean ICP, ICP pulse amplitude, respiratory waves, slow waves and the RAP index of supra- and infratentorial ICP signals. Then, we measured transtentorial difference and performed correlation analysis for every index.Supratentorial ICP mean was 8.5 mmHg lower than infratentorial ICP, but the difference lessens for higher values. Both signals across the tentorium showed close correlation. Supra- and infratentorial pulse amplitude, respiratory waves and slow waves also showed a high degree of correlation. The compensatory reserve (RAP) showed good correlation. In this case report, we demonstrate that the mean value of ICP is higher in the posterior fossa, with a strong correlation across the tentorium. All other ICP-derived parameters display a symmetrical profile.

Increasing global awareness of timely COVID-19 healthcare guidelines through FPV training tutorials: Portable public health crises teaching method.

INTRODUCTION: The current COVID-19 pandemic has prompted a timely response from the healthcare system train a large and diverse group of healthcare workers/responders swiftly. METHODS: In order to address this need, we created a downloadable pedagogical video content through first-person point-of-view to rapidly train users on COVID-19 procedures in the Revinax® Handbook mobile App. Eight new tutorials were designed through this technology platform to assist healthcare workers/responders caring for COVID-19 patients. A survey was then sent to assess their interest. RESULTS: In one-month since the App was created, it was downloaded by 12,516 users and a feedback survey determined that the users valued the tutorials in helping them learn COVID-19 procedures efficiently in real-time. The fast-growing number of downloads and positive user feedback evidences that we created a valuable educational tool with an emergent- and growing-demand. DISCUSSION: The 71.48% App user response rate, showed largely positive feedback of the COVID-19 tutorial. The fact that these healthcare workers/responders took the time to complete the survey during a pandemic was indicative of its immediate value. Further, the App users indicated that they FPV tutorial was rather helpful in addressing their training needs regarding their roles in COVID-19 patient care during the pandemic. CONCLUSION: The tutorials were deployed to offer efficient and rapid global public health educational outreach as a tool to address COVID-19 healthcare training in a timely manner.

Brainstem hemorrhage following decompressive craniectomy.

Decompressive craniectomy (DC) is used for the management of refractory raised intracranial pressure, but the impact of DC on surgical outcome is still controversial. We report a 21-year-old man admitted to our hospital after a road traffic accident. The brain CT scan revealed a left hemispheric acute subdural hematoma. After DC, he developed a brainstem hemorrhage. Recovery was, however, good.