Anaesthesia and intensive care
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Anaesth Intensive Care · May 2008
Identification of genetic mutations in Australian malignant hyperthermia families using sequencing of RYR1 hotspots.
Advances in analysis of the RYR1 gene (which encodes the skeletal muscle ryanodine receptor) show that genetic examination is a useful adjunct to the in vitro contracture test in the diagnosis of malignant hyperthermia, as defects in RYR1 have been shown to be responsible for malignant hyperthermia susceptibility. DNA from 34 malignant hyperthermia susceptible individuals and four malignant hyperthermia equivocal subjects was examined using direct sequencing of 'hot-spots' in the RYR1 gene to identify mutations associated with malignant hyperthermia. Seven different causative mutations (as defined by the European Malignant Hyperthermia Group) in nine malignant hyperthermia susceptible individuals were identified. ⋯ Based on the number of relatives presenting to our unit in the study period, the muscle biopsy rate would have decreased by 25%. That we only identified a genetic defect in RYR1 in 47% of in vitro contracture test positive individuals suggests that there are other areas in RYR1 where pathogenic mutations may occur and that RYR1 may not be the sole gene associated with malignant hyperthermia. It may also reflect a less than 100% specificity of the in vitro contracture test.
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Anaesth Intensive Care · May 2008
Review Meta AnalysisImpact of selective decontamination of the digestive tract on carriage and infection due to Gram-negative and Gram-positive bacteria: a systematic review of randomised controlled trials.
Meta-analyses of randomised controlled trials of selective digestive decontamination have clinical outcome measures, mainly pneumonia and mortality. This meta-analysis has a microbiological endpoint and explores the impact of selective digestive decontamination on Gram-negative and Gram-positive carriage and severe infections. We searched electronic databases, Cochrane Register of Controlled Trials, previous meta-analyses and conference proceedings with no language restrictions. ⋯ Gram-positive bloodstream infections were not significantly increased (OR 1.03, 95% CI 0.75 to 1.41). The association of parenteral and enteral antimicrobials was superior to enteral antimicrobials in reducing carriage and severe infections due to Gram-negative bacteria. This meta-analysis confirms that selective digestive decontamination mainly targets Gram-negative bacteria; it does not show a significant increase in Gram-positive infection.
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Anaesth Intensive Care · May 2008
Review Meta AnalysisUse of intrathecal midazolam to improve perioperative analgesia: a meta-analysis.
Intrathecal midazolam binds with gamma aminobutyric acid-A receptors in the spinal cord leading to an analgesic effect. Clinical studies suggested that intrathecal midazolam may also reduce nausea and vomiting when used as an adjunct to other spinal medications. However, the potential neurotoxic effect of intrathecal midazolam remains a concern. ⋯ The incidence of neurological symptoms after intrathecal midazolam was uncommon (1.8%) and did not differ from placebo (odds ratio 1.20, 95% CI 0.22 to 6.68, P=0.84). Based on the limited data available, intrathecal midazolam appears to improve perioperative analgesia and reduce nausea and vomiting during caesarean delivery. A multicentre registry or large randomised controlled study with a prolonged follow-up period would be useful to confirm the clinical safety of intrathecal midazolam.
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Anaesth Intensive Care · May 2008
Randomized Controlled Trial Comparative StudyComparison of potency of ephedrine and mephentermine for prevention of post-spinal hypotension in caesarean section.
The dosages and potency of intravenous mephentermine for prevention of post-spinal hypotension are not available in English literature. This study was designed to determine the minimum effective dose (ED50) of mephentermine and to compare its potency with that of ephedrine for prevention of post-spinal hypotension in parturients undergoing caesarean section. Dixon's up-down method of sequential allocation was used for vasopressor doses. ⋯ For mephentermine, the up-down method was abandoned due to the success of the minimum dose possible but the ED50 appeared to be less than 5 mg. In conclusion, the minimum effective dose of mephentermine is much less than that of ephedrine for prevention of post-spinal hypotension. Another trial with a lower starting dose and smaller dose interval of mephentermine is required to determine the potency ratio of mephentermine and ephedrine.