Anaesthesia
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Randomized Controlled Trial Comparative Study
A randomised cross-over comparison of the transverse and longitudinal techniques for ultrasound-guided identification of the cricothyroid membrane in morbidly obese subjects.
We compared the transverse and longitudinal approaches to ultrasound-guided identification of the cricothyroid membrane, to determine which was faster and more successful. Forty-two anaesthetists received a one-hour structured training programme consisting of e-learning, a lecture and hands-on training, and then applied both techniques in a randomised, cross-over sequence to obese females with body mass index 39.0 - 43.9 kg.m(-2). The mean (SD) time to identify the cricothyroid membrane was 24.0 (12.4) s using the transverse technique compared with 37.6 (17.9) s for the longitudinal technique (p = 0.0003). ⋯ All anaesthetists were successful in identifying the cricothyroid membrane with at least one of the techniques. We advocate the learning and application of these two techniques for identification of the cricothyroid membrane before starting anaesthesia in difficult patients, especially when anatomical landmarks are impalpable. Further use in emergency situations is feasible, if clinicians have experience and the ultrasound machine is readily available.
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Observational Study
Alterations in coagulation following major liver resection.
The international normalised ratio is frequently raised in patients who have undergone major liver resection, and is assumed to represent a potential bleeding risk. However, these patients have an increased risk of venous thromboembolic events, despite conventional coagulation tests indicating hypocoagulability. This prospective, observational study of patients undergoing major hepatic resection analysed the serial changes in coagulation in the early postoperative period. ⋯ Levels of factor VIII and Von Willebrand factor were significantly elevated from postoperative day one (p < 0.01). Levels of the anticoagulants, protein C and antithrombin remained significantly depressed on postoperative day five (p = 0.01). Overall, the imbalance between pro- and anticoagulant factors suggested a prothrombotic environment in the early postoperative period.
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Randomized Controlled Trial
The minimum effective concentration (MEC90 ) of ropivacaine for ultrasound-guided supraclavicular brachial plexus block.
The aim of this study was to determine the minimum effective concentration of ropivacaine for ultrasound-guided supraclavicular brachial plexus block. Fifty-one patients undergoing arm surgery received double-injection ultrasound-guided supraclavicular block using ropivacaine 40 ml. The concentration of ropivacaine administered to each patient started at 0.225% and then depended on the response of the previous one, based on a biased coin design up-and-down sequential method. ⋯ In the case of a successful block, the next patient was randomised to the same concentration or a concentration 0.025% w/v less. Success was defined as complete sensory blockade of the brachial plexus 30 min after the block together with pain-free surgery. The minimum effective ropivacaine concentration in 90% of subjects was 0.257% w/v (95% CI 0.241-0.280%).
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The importance and variability of pre-operative anaemia in cardiac surgical patients across the UK is not known, and there is debate about its association with patient outcomes. The Association of Cardiothoracic Anaesthetists carried out its first national audit on anaemia and transfusion, and analysed data from 19,033 patients operated on in 12 cardiac surgical centres between 2010 and 2012; 5895 (31%) had pre-operative anaemia. Centre-specific prevalence of anaemia varied from 23% to 45%; anaemia was associated with older patients, diabetes and surgical risk (EuroSCORE). ⋯ Haemoglobin concentration per se was also independently associated with worse outcomes; a 10 g.l(-1) decrease in haemoglobin was associated with a 43% increase (95% confidence interval 40-46%) in the odds of transfusion and a 16% increase (95% confidence interval 10-22%) in the odds of mortality (both p < 0.001). This large UK-wide audit has demonstrated marked regional variation in both anaemia and transfusion, with a consistently high incidence of both. The independent association between pre-operative anaemia and worse outcomes in UK practice has also been confirmed, and robust prospective study of anaemia treatment before cardiac surgery is required; these data will assist in designing such trials.