British journal of anaesthesia
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It is not possible to distinguish between direct pharmacological effects and immune-mediated hypersensitivity reactions by clinical observation alone and errors may occur in the absence of laboratory tests. A convenient and simple test is the measurement of plasma complement C3 consumption and conversion in sequential blood samples taken at intervals over the 24 h following an adverse response.
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Equations have been derived to determine the alveolar gas concentrations which occur when the Magill (Mapleson A) circuit is used with a low fresh gas flow. Alveolar oxygen and carbon dioxide concentrations are determined by the fresh gas flow and composition, carbon dioxide output and oxygen uptake. Gas mixing within the circuit and alterations in the inspired gas concentrations do not affect the final equilibrium. If oxygen uptake and carbon dioxide output are constant, the alveolar gas concentrations are unaffected by alterations in ventilation.
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Randomized Controlled Trial Comparative Study Clinical Trial
Intradermal study of a new local anaesthetic agent aptocaine.
In a double-blind trial in 28 human volunteers, a new local anaesthetic agent, aptocaine, was compared intradermally at 1, 2 and 3% concentrations with lignocaine 2% and bupivacaine 0.5%. In a second trial in 27 subjects, 1% aptocaine was compared with mepivacaine and prilocaine, both 1, 2 and 3%. In terms of activity as determined by area of anaesthesia, and of duration of action, aptocaine was similar to mepivacaine and more active and long-lasting than lignocaine and prilocaine. ⋯ Duration of action was unaffected by concentration. Aptocaine had marked vasoconstrictor activity, which was maximal at 1%. These local anaesthetic properties suggest that aptocaine merits clinical trials, especially in dentistry.
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The effect of the physical characteristics of the carrier gas on the output of automatic plenum vaporizers was studied. The Vapor and Fluomatic halothane output at all dial settings was highest with oxygen as the carrier gas, as compared with helium and nitrous oxide and was a function of carrier gas viscosity at all dial settings. The output of the Fluotec Mark 2 at the 0.5 and 1% settings was highest with nitrous oxide as the carrier gas, but at 2, 3 and 4% settings it was highest with oxygen; at the 0.5% and 1% dial settings it was a function of carrier gas density, but at 2%, 3% and 4% it was a function of carrier gas viscosity.
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A young patient with a head injury inhaled a dental plate 60 hr after injury.