British journal of anaesthesia
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Clinical Trial Controlled Clinical Trial
Mid-latency auditory evoked response during propofol and alfentanil anaesthesia.
Propofol has been shown to affect the mid-latency auditory evoked response (MLAER) in a dose-dependant manner. Few studies have investigated the addition of alfentanil. Myogenic responses, such as the post-auricular responses (PAR), can confound the MLAER but there has been little investigation as to which electrode site reduces this interference. ⋯ Addition of alfentanil lowers the propofol infusion rate required to produce unconsciousness and the Nb latency that predicts it. The better of the two sites to reduce the incidence of PAR is the vertex-inion electrode site.
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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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Cardiac tamponade is a serious complication of central venous catheter (CVC) insertion. Current guidelines strongly advise that the CVC tip should be located in the superior vena cava (SVC) and outside the pericardial sac. This may be difficult to verify as the exact location of the pericardium cannot be seen on a normal chest x-ray. The carina is an alternative radiographic marker for correct CVC placement, suggested on the basis of studies of embalmed cadavers. ⋯ We confirm that the carina is a reliable, simple anatomical landmark that can be identified in vivo for the correct placement of CVCs outside the boundaries of the pericardial sac.
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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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Day case surgery is becoming more acceptable, even for patients with complex medical conditions. Current recommendations suggest that patients who are graded as American Society of Anaesthesiologists physical status (ASA) III may be suitable for this approach. There is only a small amount of published data available to support this. We present a retrospective review of ASA III patients who had undergone day surgical procedures in our unit. ⋯ With good pre-assessment and adequate preparation ASA III patients can be treated safely in the day surgery setting.