Neurocritical care
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In ischemic stroke, cerebral autoregulation and neurovascular coupling may become impaired. The cerebral blood flow (CBF) response to spreading depolarization (SD) is governed by neurovascular coupling. SDs recur in the ischemic penumbra and reduce neuronal viability by the insufficiency of the CBF response. Autoregulatory failure and SD may coexist in acute brain injury. Here, we set out to explore the interplay between the impairment of cerebrovascular autoregulation, SD occurrence, and the evolution of the SD-coupled CBF response. ⋯ We propose that the dysfunction of cerebrovascular autoregulation that occurs simultaneously with hypotension transients poses a substantial risk of SD occurrence and is not a consequence of SD. Under such circumstances, the evolving SD is not accompanied by any recognizable CBF response, which indicates a severely damaged neurovascular coupling.
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Review Meta Analysis
The Effect of Hyperoxemia on Neurological Outcomes of Adult Patients: A Systematic Review and Meta-Analysis.
Hyperoxemia commonly occurs in clinical practice and is often left untreated. Many studies have shown increased mortality in patients with hyperoxemia, but data on neurological outcome in these patients are conflicting, despite worsened neurological outcome found in preclinical studies. To investigate the association between hyperoxemia and neurological outcome in adult patients, we performed a systematic review and meta-analysis of observational studies. ⋯ These associations were pronounced in patients with subarachnoid hemorrhage (RR 1.34, 95% CI 1.14-1.56) and ischemic stroke (RR 1.41, 95% CI 1.14-1.74), but not in patients with cardiac arrest, traumatic brain injury, or following cardiopulmonary bypass. Hyperoxemia is associated with poor neurological outcome, especially in patients with subarachnoid hemorrhage and ischemic stroke. Although our study cannot establish causality, PaO2 should be monitored closely because hyperoxemia may be associated with worsened patient outcome and consequently affect the patient's quality of life.
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Review Meta Analysis
A Comparison Between Enteral and Intravenous Nimodipine in Subarachnoid Hemorrhage: A Systematic Review and Network Meta-Analysis.
Our objective was to compare the effectiveness of intravenous and enteral nimodipine in preventing poor outcome from delayed cerebral ischemia in patients with subarachnoid hemorrhage. We performed a systematic search and a network meta-analysis using the following databases: PubMed, Scopus, the Cochrane Central Register of Controlled Trials, and Google Scholar. Risk of Bias 2 tool was used to assess risk of bias of included studies. ⋯ Evolving clinical protocols over a 30-year period and the risk of bias of the included studies may limit the strength of our results. Enteral and intravenous nimodipine may have a similar effectiveness in terms of preventing poor outcome, delayed cerebral ischemia, and delayed ischaemic neurological deficit. More research may be needed to fully establish the role of intravenous nimodipine in current clinical practice.
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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.