Anaesthesia
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Review Meta Analysis
Ultrasound for central venous cannulation: economic evaluation of cost-effectiveness.
We compared the economics of using two-dimensional ultrasound locating devices and more traditional landmark methods for central venous cannulation in the National Health Service (NHS). The evaluation consisted of a systematic review of randomised controlled trials and an economic evaluation using decision analytic cost-effectiveness modelling. Incremental costs per complication avoided associated with landmark and ultrasound central venous cannulation were modelled for patients scheduled for central venous cannulation. ⋯ The base case scenario implied that 2000 pounds sterling worth of resource savings result for every 1000 procedures undertaken and 90 avoided complications. Sensitivity analysis indicated that the results of modelling appear robust to the central assumptions used. Ultrasound guidance used in central venous cannulation procedures saves NHS resources even with conservative modelling assumptions.
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Caesarean section carries a high risk of awareness, especially in the period prior to neonatal delivery. We investigated the concentration of sevoflurane required to maintain bispectral index (BIS) < 60 until delivery occurred. We enrolled 23 parturients into an up-down sequential allocation study. ⋯ The EC(50) for sevoflurane was 1.22% (1.08-1.33, 95% CI). The probability of maintaining BIS < 60 was < 55% at a concentration of < 1.1%; this increased to 80% at concentrations of 1.2-1.3%. We conclude that sevoflurane concentrations of at least 1.2-1.3% should be administered in uncomplicated Caesarean section, so as to minimise the risk of awareness and recall.
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Alterations of electrolytes and albumin cause metabolic acid-base disorders. It is unclear, however, to what degree these plasma components affect the overall metabolic acid-base state in the course of critical illness. We performed serial analyses of the metabolic acid-base state in 30 critically ill patients over the course of 1 week. ⋯ Changes in serum chloride and unmeasured anions were responsible for changes of 41% and 22% in the metabolic acid-base state, respectively. Sodium and albumin played a minor role. In conclusion, chloride is the major determinant of metabolic acid-base state in critical illness.
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Randomized Controlled Trial Clinical Trial
Manual versus target-controlled infusions of propofol.
Target-controlled infusion systems have been shown to result in the administration of larger doses of propofol, which may result in delayed emergence and recovery from anaesthesia. The aim of this study was to investigate if this was due to a difference in the depth of hypnosis (using the bispectral index monitoring) between the manual and target controlled systems of administration. Fifty unpremedicated patients undergoing elective surgery were randomly allocated to have their anaesthesia maintained with manual or target-controlled propofol infusion schemes. ⋯ The difference in the total dosage of propofol was mainly due to higher rate of propofol administration in the first 30 min in the target controlled infusion group. The bispectral index scores were lower in the target controlled group during this time, being significantly so over the first 15 min of anaesthesia. We conclude that propofol administration by a target controlled infusion system results in the administration of higher doses of propofol and lower bispectral index values mainly in the initial period of anaesthesia.