Neurocritical care
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Observational Study
Comparison of Clevidipine and Nicardipine for Acute Blood Pressure Reduction in Hemorrhagic Stroke.
Intracranial hemorrhage is associated with high mortality and morbidity. Lowering systolic blood pressure (SBP) with an intravenous antihypertensive, such as nicardipine or clevidipine, may reduce the risk of hematoma expansion and rebleeding. Previous studies comparing nicardipine and clevidipine in patients with stroke found no significant difference in blood pressure management. The inclusion of patients with ischemic stroke limited those studies because of convoluted results related to faster door-to-needle times. The purpose of this study was to compare clevidipine with nicardipine in time to goal SBP in hemorrhagic stroke. ⋯ In patients with hemorrhagic stroke, nicardipine appeared to have similar efficacy as clevidipine in SBP reduction, with a more likely reduction of rebound hypertension and drug cost. This retrospective study was underpowered, which may limit these implications. Further prospective studies are warranted to confirm these results.
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Delayed cerebral ischemia (DCI) is a common complication of aneurysmal subarachnoid hemorrhage and contributes to unfavorable outcome. In patients with deterioration despite prophylactic nimodipine treatment, induced hypertension (iHTN) can be considered, although the safety and efficacy of induction are still a matter of debate. In this study, two iHTN treatment algorithms were compared with different approaches toward setting pressure targets. ⋯ Immediate induction of hypertension with higher pressure targets did not result in a lower rate of DCI-related infarctions but was not associated with a higher complication rate compared with an incremental approach. Future tailored blood pressure management based on patient- and time-point-specific needs will hopefully better balance the neurological advantages versus the systemic complications of induced hypertension.
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Within 2 min of severe ischemia, spreading depolarization (SD) propagates like a wave through compromised gray matter of the higher brain. More SDs arise over hours in adjacent tissue, expanding the neuronal damage. This period represents a therapeutic window to inhibit SD and so reduce impending tissue injury. Yet most neuroscientists assume that the course of early brain injury can be explained by glutamate excitotoxicity, the concept that immediate glutamate release promotes early and downstream brain injury. There are many problems with glutamate release being the unseen culprit, the most practical being that the concept has yielded zero therapeutics over the past 30 years. But the basic science is also flawed, arising from dubious foundational observations beginning in the 1950s METHODS: Literature pertaining to excitotoxicity and to SD over the past 60 years is critiqued. ⋯ Spreading depolarizations better account for the acute neuronal injury arising from brain ischemia than does the early and excessive release of glutamate.
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Review
The Critical Role of Spreading Depolarizations in Early Brain Injury: Consensus and Contention.
When a patient arrives in the emergency department following a stroke, a traumatic brain injury, or sudden cardiac arrest, there is no therapeutic drug available to help protect their jeopardized neurons. One crucial reason is that we have not identified the molecular mechanisms leading to electrical failure, neuronal swelling, and blood vessel constriction in newly injured gray matter. All three result from a process termed spreading depolarization (SD). Because we only partially understand SD, we lack molecular targets and biomarkers to help neurons survive after losing their blood flow and then undergoing recurrent SD. ⋯ Finally, we summarize points of consensus and contention among the authors as well as where SD research may be heading. In an accompanying review, we critique the role of the glutamate excitotoxicity theory, how it has shaped SD research, and its questionable importance to the study of early brain injury as compared with SD theory.