British journal of anaesthesia
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Unresolved surgical inflammation might induce chronic cognitive decline in older adults. Although inflammatory biomarkers have been correlated with perioperative cognitive impairment and delirium, the effects of prolonged inflammation on cognition are not well studied. This prospective cohort study investigated 1-yr dynamics in plasma interleukin-6 levels and executive function. ⋯ NCT01980511, NCT03124303.
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Cortical excitability is higher in unconsciousness than in wakefulness, but it is unclear how this relates to anaesthesia. We investigated cortical excitability in response to dexmedetomidine, the effects of which are not fully known. ⋯ Transcranial magnetic stimulation-evoked potential amplitude changes non-linearly as a function of depth of sedation by dexmedetomidine, with a region-specific paradoxical increase. Future research should investigate other anaesthetics to elucidate the link between cortical excitability and depth of sedation.
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Editorial Comment
Improving pulse oximetry accuracy in dark-skinned patients: technical aspects and current regulations.
Recent concerns regarding the clinical accuracy of pulse oximetry in dark-skinned patients, specifically in detecting occult hypoxaemia, have motivated research on this topic and recently reported in this journal. We provide an overview of the technical aspects of the issue, the sources of inaccuracy, and the current regulations and limitations. These insights offer perspectives on how pulse oximetry can be improved to address these potential limitations.
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A recent systematic review and meta-analysis by Wang and colleagues in the British Journal of Anaesthesia calls into question the concept that perioperative benzodiazepine administration is associated with development of postoperative delirium in older individuals after anaesthesia and surgery. This editorial focuses on potential bias within the systematic review and addresses major concerns surrounding benzodiazepine use in the older perioperative population.
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Variability is high in predicted propofol concentrations during clinical anaesthesia titrated by target-controlled infusion (TCI) to maintain a processed EEG parameter (bispectral index [BIS]) within a specified range. We have shown that the potential for improving the pharmacokinetic model is minimal. The drug titration paradox revealed that titration challenges the classical relationship between drug dose and effect in both individuals and the population. We hypothesised that dynamic factors during surgery beyond the static genetic, epigenetic, and other factors such as age, height, and weight affect the necessary dose. We compared the variability of measured end-tidal sevoflurane concentrations with predicted effect-site propofol concentrations when titrated to a BIS range of 40-60, with the hypothesis that the variability in measured sevoflurane concentrations would not be less than the variability in estimated propofol concentrations. ⋯ Improvements in prediction accuracy of pharmacokinetic models beyond that of those already in clinical use are unlikely to reduce variability in target anaesthetic concentrations across patients in clinical practice.