British journal of anaesthesia
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Multicenter Study Observational Study
Changes in pulse pressure variation to assess preload responsiveness in mechanically ventilated patients with spontaneous breathing activity: an observational study.
Pulse pressure variation (PPV) is not reliable in predicting preload responsiveness in patients receiving mechanical with spontaneous breathing (SB) activity. We hypothesised that an increase in PPV after a tidal volume (VT) challenge (TVC) or a decrease in PPV during passive leg raising (PLR) can predict preload responsiveness in such cases. ⋯ NCT04369027 (ClinicalTrials.gov).
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The complex cellular interactions that underlie pathologies related to reduced oxygen delivery after surgery are poorly defined and difficult to measure. Heywood and colleagues explored the patterns of protein expression in skin biopsies taken from a subgroup of patients enrolled in a randomised trial designed to evaluate perioperative goal-directed therapy. One of their key findings was that a failure of participants to maintain preoperative systemic oxygen delivery was associated with an upregulation of intracellular proteins involved in counteracting oxidative stress. Their study highlights the importance of oxidative stress in the perioperative setting and suggests that maintenance of baseline oxygen delivery might be an important regulator of redox balance.
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The cellular and molecular mechanisms by which general anaesthesia occurs is poorly understood. Hippocampal interneurone subpopulations, which are critical regulators of cognitive function, have diverse neurophysiological and synaptic properties, but their responses to anaesthetics are unclear. ⋯ Isoflurane inhibits synaptic vesicle exocytosis from hippocampal glutamatergic neurones and GABAergic interneurones in a cell-type-specific manner depending on their expression of voltage-gated sodium channel subtypes.