British journal of anaesthesia
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Randomized Controlled Trial Comparative Study
Comparative effects of dexmedetomidine, propofol, sevoflurane, and S-ketamine on regional cerebral glucose metabolism in humans: a positron emission tomography study.
The highly selective α2-agonist dexmedetomidine has become a popular sedative for neurointensive care patients. However, earlier studies have raised concern that dexmedetomidine might reduce cerebral blood flow without a concomitant decrease in metabolism. Here, we compared the effects of dexmedetomidine on the regional cerebral metabolic rate of glucose (CMRglu) with three commonly used anaesthetic drugs at equi-sedative doses. ⋯ NCT02624401.
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Review Meta Analysis
Isolated forearm technique: a meta-analysis of connected consciousness during different general anaesthesia regimens.
General anaesthesia should prevent patients from experiencing surgery, defined as connected consciousness. The isolated forearm technique (IFT) is the current gold standard for connected consciousness monitoring. We evaluated the efficacy of different anaesthesia regimens in preventing IFT responses. ⋯ Standard general anaesthesia regimens might not prevent connected consciousness. More accurate anaesthesia brain monitor methodology to reduce the likelihood of connected consciousness is desirable.
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Clinical risk factors for postoperative nausea and vomiting (PONV) are evaluated with the Apfel score, however patients with low Apfel scores still experience PONV suggesting a genetic predisposition. PONV risk associates with specific M3 muscarinic acetylcholine receptor (CHRM3) rs 2165870 polymorphism. We investigated whether the Apfel score and this genetic variation independently contribute to PONV risk and whether prophylaxis reduces PONV in patients with low Apfel score but at high genetic risk. ⋯ DRKS00005664.
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Selfhood is linked to brain processes that enable the experience of a person as a distinct entity, capable of agency. This framework naturally incorporates a continuum of both non-conscious and conscious self-related information processing, and includes a hierarchy of components, such as awareness of existence (core self), embodied self (sentience), executive self (agency/volition), and various other higher-order cognitive processes. Consciousness relates to, but is not congruent, with selfhood; understanding the processes required for selfhood can explain the partial consciousness seen in anaesthesia. ⋯ With increasing concentrations of anaesthetics, it is not uncommon for patients to become depersonalised (i.e. to lose sentience and agency), but retain many higher-order functions and a disembodied self-awareness, until quite high concentrations are reached. In this respect, general anaesthesia differs significantly from physiological sleep, where it appears that loss of agency and sentience parallels, or lags behind, the decrease in self-awareness. Interestingly, connectivity within the posterior brain regions is maintained even to quite high concentrations of anaesthetics, potentially representing a pathognomonic marker of the core self that possibly is involved in maintaining a reduced energy state of homeostasis.
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Both the cerebral cortex and subcortical structures play important roles in consciousness. Some evidence points to general anaesthesia-induced unconsciousness being associated with distinct patterns of superficial cortical electrophysiological oscillations, but how general anaesthetics influence deep brain neural oscillations and interactions between oscillations in humans is poorly understood. ⋯ Propofol increases alpha oscillations and attenuates gamma oscillations in both cortical and subcortical areas. The alpha-gamma phase-amplitude coupling and the functional connectivity of alpha oscillations in the anterior cingulate cortex could be specific markers for loss of consciousness.