Neurocritical care
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Use of hypertonic saline (HTS) is gaining acceptance in the neurosciences critical care unit (NCCU) based on its efficacy in reducing cerebral edema and its favorable hemodynamic profile. In the NCCU, unfamiliarity with the use of HTS may result in implementation difficulties. We report our initial experience using HTS, its ability to achieve a hypernatremic state, and adverse effects. ⋯ The use of HTS for cerebral edema requires intensive efforts by the medical team to rapidly achieve and maintain a hypernatremic state. The continuous infusion of HTS was used safely.
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It is controversial whether a low cerebral blood flow (CBF) simply reflects the severity of injury or whether ischemia contributes to the brain's injury. It is also not clear whether posttraumatic cerebral hypoperfusion results from intracranial hypertension or from pathologic changes of the cerebral vasculature. The answers to these questions have important implications for whether and how to treat a low CBF. ⋯ In patients with CBF<18 mL/100 g/minutes, intracranial hypertension plays a major causative role in the reduction in CBF. Treatment would most likely be directed at controlling intracranial pressure, but the early, severe intracranial hypertension also probably indicates a severe brain injury. For levels of CBF between 18 and 40 mL/100 g/minutes, the presence of regional hypoperfusion was a more important factor in reducing the average CBF.
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A common observation in closed head injuries is the contrecoup brain injury. As the in vivo brain is less dense than the cerebrospinal fluid (CSF), one hypothesis explaining this observation is that upon skull impact, the denser CSF moves toward the site of skull impact displacing the brain in the opposite direction, such that the initial impact of the brain parenchyma is at the contrecoup location. ⋯ The pattern of brain injury in which the contrecoup injury is greater than the coup injury is a result of initial movement of the brain in the contrecoup location. During the process of closed head injury, the brain parenchyma is initially displaced away from the site of skull impact and toward the contrecoup site resulting in the more severe brain contusion.
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Traumatic brain injury (TBI) is a major cause of morbidity and mortality with widespread social, personal, and financial implications for those who survive. TBI is caused by four main events: motor vehicle accidents, sporting injuries, falls, and assaults. Similarly to international statistics, annual incidence reports for TBI in Australia are between 100 and 288 per 100,000. ⋯ Currently, indirect brain oximetry is used for cerebral oxygenation determination, which provides some information regarding global oxygenation levels. A newly developed oximetry technique, has shown promising results for the early detection of cerebral ischemia. ptiO2 monitoring provides a safe, easy, and sensitive method of regional brain oximetry, providing a greater understanding of neurophysiological derangements and the potential for correcting abnormal oxygenation earlier, thus improving patient outcome. This article reviews the current status of bedside monitoring for patients with TBI and considers whether ptiO2 has a role in the modern intensive care setting.
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Clinical Trial
Prediction of intracranial pressure from noninvasive transocular venous and arterial hemodynamic measurements: a pilot study.
Continuous measurement of intracranial pressure (ICP) requires the invasive placement of epidural, parenchymal, or intraventricular devices. For critical single-point assessments, lumbar puncture may not always be practical. An accurate, reliable, portable and noninvasive method to estimate absolute ICP remains an elusive goal. The arteries that perfuse and the vein that drains the orbit are exposed to the ambient ICP while coursing through the cerebrospinal fluid or optic nerve. ⋯ The feasibility to estimate ICP from transocular sonographic and dynamometric data is suggested by these preliminary data. Retinal arterial properties are important in modeling the effect of ICP on the venous outflow pressure. Our pilot results serve as a basis on which to conduct a larger prospective and blinded study.