British journal of anaesthesia
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Target-controlled infusion (TCI) systems use pharmacokinetic (PK) models to predict the drug infusion rates necessary to achieve a desired target plasma or effect-site concentration. As new PK models are developed and implemented in TCI systems, there can be uncertainty as to which target concentrations are appropriate. Existing dose recommendations can serve as a point of reference to identify target concentrations suitable for clinical applications. ⋯ We identified remifentanil TCI target concentrations that resulted in drug administration similar to product label dosing recommendations. This approach did not necessarily identify target concentrations that achieve desired clinical effect, only those that are consistent with the product label recommended doses. We estimate that plasma target concentrations of 3.1-5.3 ng ml-1 are suitable for initial dosing.
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Circadian differences in the induction, maintenance, or emergence from volatile anaesthesia have not been well studied. ⋯ Our data show that circadian differences exist during emergence but not during induction or maintenance of sevoflurane or isoflurane anaesthesia. The locus coeruleus noradrenergic system may contribute to these differences.
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Coherent alpha electroencephalogram (EEG) rhythms in the frontal cortex have been correlated with the hypnotic effects of propofol and dexmedetomidine, but less is known about frontal connectivity as a state-specific correlate of unresponsiveness as compared with long-range connectivity. We aimed to distinguish dose- and state-dependent effects of dexmedetomidine and propofol on EEG connectivity. ⋯ NCT01889004.