British journal of anaesthesia
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Comparative Study
Local anaesthetic sensitivities of cloned HERG channels from human heart: comparison with HERG/MiRP1 and HERG/MiRP1 T8A.
Myocardial potassium channels are complexes formed by different subunits. The subunit composition may influence the cardiotoxic action of local anaesthetics. The effects of amide local anaesthetics on HERG channels co-expressed with the putative subunit MiRP1 have not been established. It is also unclear if the common polymorphism MiRP1(T8A) that predisposes individuals to drug-induced cardiac arrhythmia increases local-anaesthetic sensitivity of HERG/MiRP1 channels. This may suggest the presence of genetic risk factors for local-anaesthetic-induced cardiac arrhythmia. ⋯ Amide local anaesthetics target HERG and HERG/MiRP1 channels with identical potency. The effects on these ion currents may significantly contribute to local-anaesthetic-induced cardiac arrhythmia. MiRP1(T8A) does not seem to confer an increased risk of severe cardiac side-effects to carriers of this common polymorphism.
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The Fencl-Stewart approach to acid-base disorders uses five equations of varying complexity to estimate the base excess effects of the important components: the strong ion difference (sodium and chloride), the total weak acid concentration (albumin) and unmeasured ions. Although this approach is straightforward, most people would need a calculator to use the equations. We proposed four simpler equations that require only mental arithmetic and tested the hypothesis that these simpler equations would have good agreement with more complex Fencl-Stewart equations. ⋯ The simplified equations agree well with the previous, more complex equations. Our findings suggest a useful, simple way to use the Fencl-Stewart approach to analyse acid-base disorders in clinical practice.
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The goal of this investigation was to evaluate adequacy of the design of readily available paediatric cuffed tracheal tubes (CPTT). ⋯ Most cuffed paediatric tracheal tubes are poorly designed, in particular the smaller sizes. A better design of cuffed tubes with a short high-volume, low-pressure cuff, cuff-free subglottic space and adequately placed depth markings are urgently needed.
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Analysis of the bispectrum of EEG waveforms is a component of the proprietary BIS index-a commonly used commercial monitor of depth of anaesthesia. Does the use of the bispectrum give more information about depth of anaesthesia than the power spectrum? ⋯ We could not show that bispectral analysis gave more information than power spectral-based analysis. Most of the changes in the bispectral values result from decreases in the relative high frequency content of the EEG caused by anaesthesia.