British journal of anaesthesia
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'Depth of anaesthesia' monitors claim to measure hypnotic depth during general anaesthesia from the EEG, and clinicians could reasonably expect agreement between monitors if presented with the same EEG signal. We took 52 EEG signals showing intraoperative patterns of diminished anaesthesia, similar to those that occur during emergence (after surgery) and subjected them to analysis by five commercially available monitors. ⋯ Many clinical providers still rely on index values and manufacturer's recommended ranges for titration decision making. That two-thirds of cases showed discordant recommendations given identical EEG data, and that one-third signified excessive hypnotic depth where the EEG would suggest a lighter hypnotic state, emphasizes the importance of personalised EEG interpretation as an essential clinical skill.
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Clinical Trial
Breathe-squeeze: pharmacodynamics of a stimulus-free behavioural paradigm to track conscious states during sedation☆.
Conscious states are typically inferred through responses to auditory tasks and noxious stimulation. We report the use of a stimulus-free behavioural paradigm to track state transitions in responsiveness during dexmedetomidine sedation. We hypothesised that estimated dexmedetomidine effect-site (Ce) concentrations would be higher at loss of responsiveness (LOR) compared with return of responsiveness (ROR), and both would be lower than comparable studies that used stimulus-based assessments. ⋯ NCT04206059.
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The effect of postoperative delirium on the amyloid cascade of Alzheimer's dementia is poorly understood. Using early postoperative plasma biomarkers, we explored whether surgery and delirium are associated with changes in amyloid pathways. ⋯ .NCT03124303 and NCT01980511.
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Postoperative cognitive dysfunction (POCD) is a concern after anaesthesia and surgery, but preoperative discussion of neurocognitive risks with older patients rarely occurs. Anecdotal experiences of POCD are common in the popular media and may inform patient perspectives. However, the degree of alignment between lay and scientific perspectives on POCD is not known. ⋯ There is misalignment between professional and lay understandings of POCD. Lay people emphasise subjective and functional impact of symptoms, and express beliefs about the role of anaesthetics in causing POCD. Some patients and caregivers affected by POCD report feeling abandoned by medical providers. In 2018, new nomenclature for postoperative neurocognitive disorders was published, which better aligns with lay perspectives by including subjective complaints and functional decline. Further studies based on newer definitions and public messaging may improve concordance between different understandings of this postoperative syndrome.
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Sepsis-associated encephalopathy is characterised by cognitive dysfunction, and might be mediated by deficits in neurotransmission. Reduced cholinergic neurotransmission in the hippocampus impairs memory function. We assessed real-time alterations of acetylcholine neurotransmission from the medial septal nucleus to the hippocampus, and explored whether sepsis-induced cognitive deficits can be relieved by activating upstream cholinergic projections. ⋯ Systemic or local LPS reduced cholinergic neurotransmission from the medial septum to hippocampal pyramidal neurones, and their selective activation alleviated defects in hippocampal neuronal function and synaptic plasticity and ameliorated memory deficits in sepsis model mice through enhanced cholinergic neurotransmission. This provides a basis for targeting cholinergic signalling to the hippocampus in sepsis-induced encephalopathy.