Anaesthesia
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The predictive performance of a 'Diprifusor' target controlled infusion system for propofol was examined in 46 patients undergoing major surgery, divided into three age groups (18-40, 41-55 and 56-80 years). Measured arterial propofol concentrations were compared with values calculated (predicted) by the target controlled infusion system. Performance indices (median performance error and median absolute performance error) were similar in the three age groups, with study medians of 16.2% and 24.1%, respectively. ⋯ Measured concentrations tended to be higher than calculated concentrations, particularly following induction or an increase in target concentration. The mean (SD) propofol target concentration of 3.5 (0.7) micrograms.ml-1 during maintenance was lower in older patients, compared with higher target concentrations of 4.2 (0.6) and 4.3 (0.7) micrograms.ml-1 in the two younger age groups, respectively. The control of depth of anaesthesia was good in all patients and the predictive performance of the 'Diprifusor' target controlled infusion system was considered acceptable for clinical purposes.
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Seventeen experienced anaesthetists and 15 novices were filmed intubating the trachea of a training manikin. Measurements were made of the distance from manikin's chin to subject's nose and of the angles at the elbow, the shoulder and of the forearm with the horizontal. ⋯ Trained subjects tended to hold the laryngoscope closer to the hinge, with a pincer grip; novices were more likely to use a full grip of the handle. Trainers should consider giving novices explicit instructions on how to stand and how to hold the laryngoscope.
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The use of the intubating laryngeal mask in three patients is described. In two patients for whom tracheal intubation using traditional techniques had failed, the intubating laryngeal mask was used to achieve successful tracheal intubation. The trachea of one of these patients was subsequently re-intubated for a second procedure using the same technique. A third patient with a cervical spine fracture whose trachea was electively intubated using the intubating laryngeal mask is also presented.
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Serial thermodilution and impedance cardiac output measurements in two critically ill patients are presented. Impedance cardiography failed to detect changes in cardiac output and provided values lower than those derived from thermodilution. ⋯ This failure of impedance cardiography is attributed to aberrant electrical conduction though the lungs as a result of increased lung fluid that alters the impedance waveform. Although reliable when used in normal subjects, impedance cardiography appears not to provide accurate measurements in critically ill patients.