British journal of anaesthesia
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Review Meta Analysis
Effect of beta-blockers on cancer recurrence and survival: a meta-analysis of epidemiological and perioperative studies.
The biological perturbation associated with psychological and surgical stress is implicated in cancer recurrence. Preclinical evidence suggests that beta-blockers can be protective against cancer progression. We undertook a meta-analysis of epidemiological and perioperative clinical studies to investigate the association between beta-blocker use and cancer recurrence (CR), disease-free survival (DFS), and overall survival (OS). ⋯ Beta-blocker use had no evident effect on CR. The beneficial effect of beta-blockers on DFS and OS in the epidemiological or perioperative setting remains variable, tumour-specific, and of low-level evidence at present.
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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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Despite its designation as a 'dissociative anaesthetic,' the dissociative and psychoactive effects of ketamine remain incompletely understood. The goal of this study was to characterise the subjective experiences and accompanying EEG changes with subanaesthetic doses of ketamine. ⋯ Ketamine induces altered states of consciousness during periods of reduced alpha power in the precuneus and temporal-parietal junction. Modulation of these temporal-parietal loci are candidate mechanisms of the psychoactive effects of ketamine, given that this region is involved in multisensory integration, body representation, and consciousness.
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Explicit memory after anaesthesia has gained considerable attention because of its negative implications, while implicit memory, which is more elusive and lacks patients' explicit recall, has received less attention and dedicated research. This is despite the likely impact of implicit memory on postoperative long-term well-being and behaviour. Given the scarcity of human data, fear conditioning in animals offers a reliable model of implicit learning, and importantly, one where we already have a good understanding of the underlying neural circuitry in awake conditions. ⋯ In some cases, low doses of general anaesthetics can actually lead to a paradoxical opposite effect. The underlying mechanisms involve several neurotransmitter systems, acting mainly in the amygdala, hippocampus, and neocortex. Here, we review animal studies of aversive conditioning under anaesthesia, discuss the complex picture that arises, identify the gaps in knowledge that require further investigation, and highlight the potential translational relevance of the models.