Anaesthesia
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Peri-operative intravenous crystalloid probably reduces the risk of postoperative nausea and vomiting.
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Randomized Controlled Trial Comparative Study
Differential frontal alpha oscillations and mechanisms underlying loss of consciousness: a comparison between slow and fast propofol infusion rates.
Mechanisms underlying loss of consciousness following propofol administration remain incompletely understood. The objective of this study was to compare frontal lobe electroencephalography activity and brainstem reflexes during intravenous induction of general anaesthesia, in patients receiving a typical bolus dose (fast infusion) of propofol compared with a slower infusion rate. We sought to determine whether brainstem suppression ('bottom-up') predominates over loss of cortical function ('top-down'). ⋯ Alpha band power emerged several minutes after the loss of consciousness in participants allocated to the fast infusion group. Our results show a predominance of 'bottom-up' mechanisms during fast infusion rates and 'top-down' mechanisms during slow infusion rates. The underlying mechanisms by which propofol induces loss of consciousness are potentially influenced by the speed of infusion.
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Pilot and feasibility studies are preliminary investigations undertaken before a larger study. We hypothesised that only a small proportion of pilot or feasibility studies published in anaesthesia journals were correctly labelled as such. We searched for papers published between 2007 and 2017 in six anaesthesia journals using the text words 'pilot' OR 'feasibility' and included 266 original articles with 26,682 human participants. ⋯ These results have important consequences for patients, trialists, researchers and funders. We argue that correctly labelled pilot studies enhance the quality of scientific research by encouraging methodological rigour, ensuring scientific validity and reducing research waste. Authors, reviewers, editors and publishers should ensure they adhere to the contents of the 2016 CONSORT extension for pilot and feasibility studies.
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Randomized Controlled Trial
The effect of cricoid and paralaryngeal force on upper oesophageal occlusion during induction of anaesthesia: a randomised, crossover study.
The aim of this study was to evaluate the effectiveness of cricoid and paralaryngeal force for oesophageal entrance occlusion during induction of anaesthesia. Seventy-four patients were included in this randomised, crossover study. The relative position of the glottis and outer anteroposterior diameter of the upper oesophageal entrance were assessed at baseline, after the application of 30 N cricoid and paralaryngeal force, and after induction of anaesthesia. ⋯ The relative position of the upper oesophageal entrance to the glottis may change after induction of anaesthesia and during direct laryngoscopy. Cricoid and paralaryngeal force both decrease the diameter of the upper oesophageal entrance in awake and anaesthetised states. Occlusion of the oesophageal entrance is achieved more frequently with cricoid force compared with paralaryngeal force during direct laryngoscopy.
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Pre-operative anaemia is typically diagnosed with a haemoglobin concentration < 120 g.l-1 for women and < 130 g.l-1 for men on the basis of limited evidence. This retrospective cohort study stratified women undergoing elective, major abdominal surgery based on pre-operative haemoglobin concentration: anaemic (< 120 g.l-1 ); borderline anaemic (120-129 g.l-1 ); and non-anaemic (> 130 g.l-1 ). Data from 1554 women were analysed. ⋯ However, after matched cohort analysis, these outcome differences no longer remained statistically significant. After multivariable adjustment for procedure, Charlson comorbidity index and patient age, a negative relationship between logarithmic pre-operative haemoglobin concentration and duration of stay was found (parameter estimate (standard error) -0.006 (0.003) vs. 0.003 (0.003) for a haemoglobin concentration < 130 g.l-1 vs. > 130 g.l-1 , respectively; p = 0.03); the difference in duration of stay was approximately 50% greater for women with a haemoglobin concentration of 120 g.l-1 compared with those with a haemoglobin concentration of 130 g.l-1. Although the contribution of borderline anaemia to the incidence of postoperative complications is uncertain, the current diagnostic criteria should be re-assessed.