British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Saline as an alternative to air for filling the laryngeal mask airway cuff.
We have assessed a new method to evacuate saline completely from the laryngeal mask airway (LMA) cuff and tested the hypothesis that intracuff pressures, fibreoptic position and oropharyngeal leak pressures are similar for saline compared with air during nitrous oxide-oxygen anaesthesia. Eight size 4 LMA were inflated with saline 30 ml. After syringe evacuation, median residual weight was 0.56 (range 0.24-0.98) g; after additional manual cuff squeezing it was 0.26 (0.21-0.35) g; and after drying for 12 h at 60 degrees C with the valve open it was -0.02 (-0.05-0.04) g. ⋯ Oropharyngeal leak pressures were similar between groups. We conclude that the saline-inflated LMA cuff was reliably emptied and more stable in terms of intracuff pressures and possibly fibreoptic position. Filling the LMA cuff with saline is a viable option during laser surgery to the airway.
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Randomized Controlled Trial Comparative Study Clinical Trial
Haemodynamic and electroencephalographic response to insertion of a cuffed oropharyngeal airway: comparison with the laryngeal mask airway.
We have compared the cuffed oropharyngeal airway (COPA), a modified Guedel airway device with a specially designed cuff at its distal end, with the laryngeal mask airway (LMA), on haemodynamic and electroencephalographic (EEG) responses to insertion. In addition, we examined the haemodynamic and EEG changes during initiation of the effect-compartment controlled infusion. We studied 35 female patients undergoing ambulatory gynaecological surgery allocated randomly to received an LMA or COPA to manage the airway. ⋯ The effect-compartment controlled infusion of propofol caused only mild haemodynamic changes during induction. Changes in arterial pressure and heart rate after insertion were similar in both groups and not significantly different from baseline values before insertion. Changes in BIS after insertion were minor and similar between groups.
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Case Reports
Repeated transient neurological symptoms after spinal anaesthesia with hyperbaric 5% lidocaine.
We report a case of repeated delayed pain after cystoscopy under spinal lidocaine anaesthesia, which may be caused by transient radicular irritation. The possible aetiology of the symptoms is discussed.
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The pharmacokinetic models proposed for atracurium or cisatracurium are based on the assumption that spontaneous degradation via Hofmann elimination proceeds in vivo at the same rate as measured in vitro at pH 7.4 and 37 degrees C. As different degradation rates have been reported for all 10 stereoisomers of atracurium measured together, for each of its three isomeric groups, and for the single isomer cisatracurium, we studied if the rate is dependent on factors other than pH and temperature. In vitro degradation of atracurium and cisatracurium was studied at 37 degrees C and pH 7.4 in nine incubating solutions containing one of three buffer systems (phosphate, HEPES or Tris) and additives (sodium chloride, potassium sulphate or glucose). ⋯ At the same total buffer concentration (50 mmol litre-1), degradation was fastest in the phosphate, intermediate in the HEPES and slowest in the Tris buffer. Degradation rates of cisatracurium in sodium phosphate 50 mmol litre-1 and Sörensen (Na-K phosphate) buffer 66.7 mmol litre-1 were similar to those of atracurium. We conclude that, at constant pH and temperature, the degradation rate of atracurium was dependent on the total concentration of the base in the incubating solution.