Anaesthesia
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The administration of a known concentration of oxygen is an important part of routine care of the sick patient. Many devices are currently available. The actual concentration of oxygen that can be delivered by these devices can be affected by several factors, both from the patient as well as the device itself. ⋯ Variable performance systems such as the Hudson mask deliver a significantly reduced oxygen concentration at high respiratory rates. Fixed performance systems delivering 24-40% oxygen deliver appropriate oxygen concentrations across the range of respiratory rates, whereas those delivering 60% show a reduction in performance. High flow systems show no failure of performance at increased respiratory rates.
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A new safety-orientated drug infusion label was studied and was compared with conventional methods by prospectively collecting incident reports from November 1998 to November 2003. Anaesthetists were asked to return an incident form for every anaesthetic (87% response rate), the vast majority indicating that no error had occurred. One error was reported with the use of the new label. ⋯ Therefore, this data point was not included in the analysis. Seven errors were reported in the calculation of dosage using conventional infusion labels during 18 491 anaesthetics compared with no calculation errors in 10 655 anaesthetics with the new label (p = 0.045, Chi-squared test). Despite the difficulties of demonstrating significant benefit from safety initiatives in medicine, these data suggest that targeted system redesign can be effective inreducing error.
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Comparative Study
Comparison of Acute Physiology and Chronic Health Evaluation (APACHE) II score with organ failure scores to predict hospital mortality.
This study compared the performance of the Acute Physiology and Chronic Health Evaluation (APACHE) II score with two organ failure scores in predicting hospital mortality of critically ill patients. A total of 1311 consecutive adult patients in a tertiary 22-bed multidisciplinary intensive care unit (ICU) in Western Australia were considered. The APACHE II score had a better calibration and discrimination than the Max Sequential Organ Failure Score (Max SOFA) (area under receiver operating characteristic (ROC) curve 0.858 vs 0.829), Admission SOFA (area under ROC 0.858 vs 0.791), and the first day or cumulative 5-day Royal Perth Hospital Intensive Care Unit (RPHICU) organ failure score (area under ROC 0.858 vs 0.822 and 0.819, respectively) in predicting hospital mortality. The APACHE II score predicted hospital mortality of critically ill patients better than the SOFA and RPHICU organ failure scores in our ICU.
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Bispectral index values during elective rigid bronchoscopy: a prospective observational pilot study.
Rigid bronchoscopy is associated with a high incidence of haemodynamic disturbance and awareness under anaesthesia. Anaesthetic agents are given both to attenuate the sympathetic response to bronchoscopy and to prevent awareness. Use of the Bispectral index to guide anaesthesia has shown to reduce awareness and improve recovery times from general anaesthesia. ⋯ Few of our patients undergoing general anaesthesia for rigid bronchoscopy had BIS scores in the suggested range of between 40 and 60. BIS < 40 was more frequent than in previous studies of different surgical populations. There was no difference in the BIS values of patients anaesthetised with intermittent boluses or target controlled infusions of propofol.
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Clinical Trial
The optimal dose of remifentanil for intubation during sevoflurane induction without neuromuscular blockade in children.
The optimal dose of remifentanil needed to produce successful intubating conditions following inhalation induction of anaesthesia using 5% sevoflurane without the use of neuromuscular blocking drugs, was investigated in 25 children aged 3-10 years. Sixty seconds after inhalation induction of anaesthesia using sevoflurane 5% in 100% oxygen, a predetermined dose of remifentanil was injected over 30 s. The dose of remifentanil was determined using the modified Dixon's up-and-down method (0.2 microg x kg(-1) as a step size). ⋯ Ninety seconds following the bolus administration of remifentanil, the child's trachea was intubated. The optimal bolus dose of remifentanil required for successful tracheal intubation was 0.56 (0.15) microg x kg(-1) in 50% of children during inhalation induction using 5% sevoflurane in the absence of neuromuscular blocking drugs. Using probit analysis, the 95% effective dose (ED(95)) of remifentanil was 0.75 microg x kg(-1) (95% confidence limits 0.63-1.38 microg x kg(-1)).