European journal of anaesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Topical anaesthesia of the larynx: cocaine or lignocaine?
A double-blind, randomized study compared the cardiovascular responses and extubation conditions using lignocaine or cocaine for topical anaesthesia of the larynx. Absorption of both agents from the trachea was quantified by serial venous plasma concentrations. Serial blood pressure, ECG, O2 saturation and end-tidal carbon dioxide measurements were obtained. ⋯ No difference was found in cardiovascular measurements between the two groups. The patterns of absorption of cocaine and lignocaine from the laryngeal mucosa were very similar, with peak absorption occurring at 10-15 min after laryngeal spraying. Although cocaine reduced the incidence of post-operative coughing when compared with lignocaine, this did not reach statistical significance.
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In vitro contracture tests for susceptibility to malignant hyperthermia (MH) were performed in 96 patients according to the protocol of the European MH Group. In addition, tests were performed with halothane 0.44 mmol l-1 and 0.66 mmol l-1, and caffeine 2 mmol l-1, each added as a single bolus dose to fresh specimens. For all tests the size of contractures were recorded, and for the diagnostic tests the halothane and caffeine threshold concentrations were determined (i.e. the minimal concentrations eliciting a contracture of 0.2 g). ⋯ We conclude that, in our laboratory, the results obtained with the two major protocols for investigation of MH susceptibility are not identical. Patients surviving fulminant MH, however, react abnormally to nearly all the tests. For validation and possibly further standardization of the tests each laboratory must investigate a large number of normal controls and as many patients surviving fulminant MH as possible.