Anaesthesia
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Letter Practice Guideline
Peri-operative management of the obese surgical patient 2015: Association of Anaesthetists of Great Britain and Ireland Society for Obesity and Bariatric Anaesthesia.
Guidelines are presented for the organisational and clinical peri-operative management of anaesthesia and surgery for patients who are obese, along with a summary of the problems that obesity may cause peri-operatively. The advice presented is based on previously published advice, clinical studies and expert opinion.
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We measured total and free plasma concentrations of ropivacaine following high-volume, high-dose local infiltration analgesia in 28 patients aged 65 years or over undergoing unilateral total knee arthroplasty. Patients received infiltration of ropivacaine 400 mg followed by infusion at 20 mg.h(-1) through an intra-articular catheter. Total and free plasma levels of ropivacaine were measured at specified time intervals during a 24-h period after tourniquet release. ⋯ Six samples had total plasma ropivacaine levels greater the toxic threshold of 2.2 μg.ml(-1). No samples reached the toxic threshold for free venous ropivacaine concentration. We conclude that the use of high-dose ropivacaine infiltration and catheter infusion for total knee arthroplasty in an elderly population does not result in free plasma ropivacaine levels previously associated with toxicity but that raised total plasma levels may be observed.
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In a previous paper, one of the authors (JBC) used a chi-squared method to analyse the means (SD) of baseline variables, such as height or weight, from randomised controlled trials by Fujii et al., concluding that the probabilities that the reported distributions arose by chance were infinitesimally small. Subsequent testing of that chi-squared method, using simulation, suggested that the method was incorrect. This paper corrects the chi-squared method and tests its performance and the performance of Monte Carlo simulations and ANOVA to analyse the probability of random sampling. ⋯ The number of Fujii randomised controlled trials with unlikely distributions was less with Monte Carlo simulation than with the 2012 chi-squared method: 102 vs 117 trials with p < 0.05; 60 vs 86 for p < 0.01; 30 vs 56 for p < 0.001; and 12 vs 24 for p < 0.00001, respectively. The Monte Carlo analysis nevertheless confirmed the original conclusion that the distribution of the data presented by Fujii et al. was extremely unlikely to have arisen from observed data. The Monte Carlo analysis may be an appropriate screening tool to check for non-random (i.e. unreliable) data in randomised controlled trials submitted to journals.
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We have developed a peripheral nerve catheter, attached to a needle, which works like an adjustable suture. We used in-plane ultrasound guidance to place 45 catheters close to the femoral, saphenous, sciatic and distal tibial nerves in cadaver legs. ⋯ In 10 cases, we confirmed catheter position by magnetic resonance imaging. We judged 43/45 initial placements successful and 42/43 secondary placements successful by ultrasound, confirmed in 10/10 cases by magnetic resonance imaging.