Anaesthesia and intensive care
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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.
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Anaesth Intensive Care · May 2008
Randomized Controlled Trial Comparative StudyComparison of the laryngeal mask (LMA) and laryngeal tube (LT) with the perilaryngeal airway (cobraPLA) in brief paediatric surgical procedures.
We compared the laryngeal mask airway (LMA) and the laryngeal tube (LT) with the perilaryngeal airway (CobraPLA, PLA) in anaesthetised, paralysed children having brief surgical procedures. After obtaining informed consent, 90 paediatric ASA Status 1 and 2 patients awaiting short surgical procedures were randomised to have their airways managed with an LMA, LT or PLA. Anaesthesia was induced with sevoflurane (2.5 to 4%) and muscle paralysis with mivacurium (0.2 mg/kg intravenously). ⋯ The number and type of airway interventions to achieve an effective airway were comparable. When the airways were removed, positive blood traces were noted on 20% of the LMAs, 20% of the PLAs and 10% of the LTs. Haemodynamic, ventilation and oxygenation variables throughout the surgery were similar with LMA, LT and PLA and there were no significant differences in insertion time or signs or symptoms of mucosal trauma when these devices were used in paralysed children.
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Anaesth Intensive Care · May 2008
Randomized Controlled Trial Comparative StudyIntra-ocular pressure changes associated with intubation with the intubating laryngeal mask airway compared with conventional laryngoscopy.
This open, prospective, randomised study was designed to evaluate the changes in intra-ocular pressure and haemodynamics after tracheal intubation using either the intubating laryngeal mask airway (ILMA) or direct laryngoscopy. Sixty adult patients, ASA physical status 1 or 2 with normal intra-ocular pressure were randomly allocated to one of the two techniques. Anaesthesia was induced with propofol followed by rocuronium. ⋯ Mucosal trauma was more frequent with the ILMA (eight of 30) compared with the laryngoscopy group (three of 30) (P<0.01). The postoperative complications were comparable. In terms of minimising increases in intra-ocular pressure and blood pressure, we conclude that the ILMA has an advantage over direct laryngoscopy for tracheal intubation.
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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.