Anesthesiology
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Mouth opening and the resistance to opening developed by the muscles of mastication were measured in 63 children anesthetized with halothane and relaxed with succinylcholine, pancuronium, or vecuronium. Measurement of mouth opening, induced by a constant test force, was made when each patient was deeply anesthetized, as judged by clinical parameters. Succinylcholine, vecuronium, or pancuronium was then administered. ⋯ Anesthesia and surgery proceeded in all patients. None of the patients developed malignant hyperthermia. In view of the fact that a reduction in mouth opening was a constant finding when succinylcholine was administered during halothane anesthesia, the assumption that isolated "masseter spasm" or jaw stiffness heralds malignant hyperthermia should be reconsidered.
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Comparative Study
Differential use-dependent (frequency-dependent) effects in single mammalian axons: data and clinical considerations.
The potential clinical scope of use-dependent block of conduction (UDB) was assessed by studying characteristics of UDB in vitro in individual mammalian axons. Single and repetitive stimulation was applied to rabbit cervical sympathetic and vagus nerves exposed to solutions containing lidocaine 0, 0.3, or 0.6 mmol/l (9.1 or 18.2 mg/dl) at 37 degrees C. Unit responses were recorded in dissected filaments or extracellularly in the vagus nodose ganglion. ⋯ With lidocaine 0.6 mM, the incidence of equilibrium conduction block was too high among sympathetic axons to assess UDB, and significantly higher than among nonsympathetic myelinated and unmyelinated units. The observations support the hypothesis that the differential block of sympathetics observed clinically with spinal anesthesia may be, at least in part, a use-dependent (frequency-dependent) effect. UDB seems unlikely to contribute to local anesthetic block of pain impulses.
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Comparative Study Clinical Trial
General or spinal anesthesia: which is better in the elderly?