British journal of anaesthesia
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Eleven anaesthetists completed a simulated anaesthetic which was deliberately complicated by a slow progressive bradycardia followed by an episode of severe bronchospasm. After the simulation, each anaesthetist was asked to complete an anaesthetic chart and a critical incident report. Considerable discrepancies were found between the anaesthetists' written accounts, a videotape of their performance and actual data from the simulator. ⋯ Only four anaesthetists mentioned bradycardia in their written description and none accurately described the changes in arterial pressure during the episode of bronchospasm. The findings are in keeping with other studies which suggest that people record events as "schemata" rather than as collections of discrete facts. These results have significant implications for those involved in the teaching of anaesthesia and in the analysis of critical incidents.
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Randomized Controlled Trial Comparative Study Clinical Trial
Central nervous and cardiovascular effects of i.v. infusions of ropivacaine, bupivacaine and placebo in volunteers.
We have compared the incidence of CNS symptoms and changes in echocardiography and electrophysiology during i.v. infusions of ropivacaine, bupivacaine and placebo. Acute tolerance of i.v. infusion of 10 mg min-1 was studied in a crossover, randomized, double-blind study in 12 volunteers previously acquainted with the CNS effects of lignocaine. The maximum tolerated dose for CNS symptoms was higher after ropivacaine in nine of 12 subjects and higher after bupivacaine in three subjects. ⋯ A threshold for CNS toxicity was apparent at a mean free plasma concentration of approximately 0.6 mg litre-1 for ropivacaine and 0.3 mg litre-1 for bupivacaine. Bupivacaine increased QRS width during sinus rhythm compared with placebo (P < 0.001) and ropivacaine (P < 0.01). Bupivacaine reduced both left ventricular systolic and diastolic function compared with placebo (P < 0.05 and P < 0.01, respectively), while ropivacaine reduced only systolic function (P < 0.01).
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Randomized Controlled Trial Clinical Trial
Effect of lignocaine and pH on propofol-induced pain.
Propofol has the disadvantage of pain on injection. A higher partition of propofol in the aqueous phase of the preparation causes a higher incidence of pain on injection while addition of 1% lignocaine to propofol reduces pain. The low concentration of this local anaesthetic and the rapid pain relief observed indicates that mechanisms other than local anaesthesia are involved, that is change in pH. ⋯ The concentration of propofol in the aqueous phase was lower when 1% Diprivan was mixed with 1% lignocaine (0.376 g litre-1) or HCl (0.392 g litre-1) compared with 1% Diprivan and saline (0.476 g litre-1) mixed in the same proportion. Thus pH changes may modify propofol-induced pain on injection by a mechanism different from the effect of the local anaesthetic on the vascular endothelium. Our findings may explain why lignocaine mixed with propofol causes less pain than injection of lignocaine followed by propofol.