British journal of anaesthesia
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The successful management of a 29-yr-old patient with tracheal separation between rings one and two after attempted hanging is described. Increasing difficulty with ventilation via a tracheal tube and surgical emphysema indicated the need for a tracheostomy. The diagnosis was made during the tracheostomy procedure when it was observed that the tracheal tube was protruding through the incomplete transection of the trachea such that Murphy's eye was aligned with the lower tracheal stump. ⋯ The signs and symptoms of laryngotracheal separation after blunt trauma are described. A review of the airway management has been made as it requires combined anaesthetic and surgical expertise. Injuries to the trachea may have severe, life-threatening consequences and early diagnosis and management reduce morbidity and mortality.
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Percutaneous dilatation tracheostomy has become a common procedure for bedside insertion of tracheostomy tubes in the intensive care unit. Management of the airway during the procedure using the laryngeal mask airway (LMA) and other methods has been described. ⋯ These include the use of both the fibreoptic bronchoscope and tracheal tube if necessary. We report the results of a pilot study of 10 patients that illustrates these advantages.
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Several cases have been reported in which symptoms suggestive of transient radicular irritation occurred after the use of lidocaine (lignocaine) for spinal anaesthesia. We report three patients in whom we observed similar symptoms after uneventful spinal anaesthesia using isobaric 2% mepivacaine.
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Comparative Study
Critical haemoglobin concentration in anaesthetized dogs: comparison of two plasma substitutes.
We have explored systemic and regional tolerance to haemodilution during anaesthesia with two different synthetic colloids. Eighteen dogs undergoing mechanical ventilation during anaesthesia with ketamine were submitted to progressive normovolaemic haemodilution with either gelatin (GEL; n = 9) or hydroxyethylstarch (HES; n = 9) administered on a 1:1 ratio. Systemic oxygen delivery was calculated from measurement of thermodilution cardiac output and arterial oxygen content, while systemic oxygen consumption was determined from expired gas analysis. ⋯ The mesenteric critical oxygen extraction ratio (O2ER) (GEL 50.1 (12.1)%; HES 48.5 (13.4)%) was significant lower than the systemic critical O2ER (GEL 66.1 (8.4)%; HES 67.7 (7.1)%). There were no significant differences between the GEL and HES groups for any of these variables, or in the amount of colloid administered. During the study, oxygen delivery decreased almost linearly with reduction in haemoglobin, indicating a lack of cardiac output response to anaemia during ketamine anaesthesia.
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We have evaluated the effect of delivering nitric oxide using a continuous flow system (CFS) or two commercially available proportional gas injection systems (PGIS), Nodomo (Dräger, Lübeck, Germany) and Pulmonox-Mini (Messer Griesheim Austria, Gumpoldskirchen, Austria) on measured and simulated concentrations of nitric oxide. Nitric oxide concentration was measured in a bench test at five sites in the inspiratory breathing system during volume- or pressure-controlled ventilation and mathematically simulated using a mixing chamber model. For a target concentration of 10 parts per million (ppm) at the "Y" piece, simulated nitric oxide concentrations were 1.9-139 ppm for CFS, 0.3-22 ppm for the Nodomo and 0.0-31 ppm for the Pulmonox-Mini near the nitric oxide administration site. ⋯ Measured and simulated variations depended on the nitric oxide delivery system, site of measurement and tidal volume. Measured variations were four times smaller in the Nodomo than in the Pulmonox-Mini and CFS. As inappropriate mixing may occur even with PGIS, nitric oxide should probably not be administered near the "Y" piece.