British journal of anaesthesia
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Perioperative hypotension is common and associated with poor outcomes, including acute kidney injury (AKI). The mechanistic link between perioperative hypotension and AKI is at least partly a consequence of the susceptibility of the kidney, and particularly the renal medulla, to ischaemia and hypoxia. Several critical gaps in our knowledge lead to uncertainty about when and how to intervene to prevent AKI attributable to perioperative hypotension. ⋯ Third, there is little information regarding the relative risks and benefits of various clinically available therapies (e.g. vasoconstrictors, i.v. fluids, or both) to treat and prevent perioperative hypotension, particularly with regard to renal medullary perfusion and oxygenation. Fourth, there are currently no validated, clinically feasible methods for real-time clinical monitoring of renal perfusion or oxygenation. Thus, future developments in perioperative kidney-protective strategies must rely on the development of methods to better monitor renal perfusion and oxygenation in the perioperative period, and thereby guide timing, intensity, type, and duration of interventions.
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Perioperative hypotension has been repeatedly associated with organ injury and worse outcome, yet many interventions to reduce morbidity by attempting to avoid or reverse hypotension have floundered. In part, this reflects uncertainty as to what threshold of hypotension is relevant in the perioperative setting. Shifting population-based definitions for hypertension, plus uncertainty regarding individualised norms before surgery, both present major challenges in constructing useful clinical guidelines that may help improve clinical outcomes. ⋯ Consideration of the mosaic framework is critical for a more complete understanding of the perioperative response to acute sterile and infectious inflammation. The largely arbitrary treatment of perioperative blood pressure remains rudimentary in the context of multiple complex adaptive hypertensive endotypes, defined by distinct functional or pathobiological mechanisms, including the regulation of reactive oxygen species, autonomic dysfunction, and inflammation. Developing coherent strategies for the management of perioperative hypotension requires smarter, mechanistically solid interventions delivered by RCTs where observer bias is minimised.
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Editorial Comment
Silver linings: will the COVID-19 pandemic instigate long overdue mental health support services for healthcare workers?
A study in this month's journal adds to the growing body of evidence regarding the potential mental health impacts on frontline healthcare staff working during the COVID-19 pandemic. As clinical academics representing critical care, nursing, and medicine, and a psychologist guiding support for frontline health and social workers, we offer our perspectives on this study. We discuss the balance between pragmatic and rigorous data collection on this topic and offer perspectives on the observed differential impact on nurses. Finally, we suggest that the pandemic might have a positive effect by instigating more robust mental health support services for National Health Service workers.
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General anaesthetics have marked effects on synaptic transmission, but their neuronal and circuit-level effects remain unclear. The volatile anaesthetic isoflurane differentially inhibits synaptic vesicle exocytosis in specific neuronal subtypes, but whether other common anaesthetics also have neurone-subtype-specific actions is unknown. ⋯ Anaesthetic-agent-selective effects on presynaptic Ca2+ entry have functional implications for hippocampal circuit function during i.v. or volatile anaesthetic-mediated anaesthesia. Hippocampal interneurones have distinct subtype-specific sensitivities to volatile anaesthetic actions on presynaptic Ca2+, which are similar between isoflurane and sevoflurane.