Articles: anesthetics.
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A series of 52 patients in whom 0.5% bupivacaine was used to produce spinal analgesia for awake Caesarean section is described. Analgesia tended to be asymmetrical and of limited extent until the patients were turned from the left lateral to the right lateral position immediately after injecting the spinal solution. This movement produced a more symmetrical block with better cephalic spread. ⋯ The mean +/- SEM time to achieve maximal spread of analgesia was 17.5 +/- 0.6 min. The mean- +/- SEM time to the administration of the first postoperative analgesic was 163.5 +/- 7.0 min. The disadvantages of the technique were hypotension and the unpredictable spread of analgesia.
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The effects of the steroid anaesthetic alphaxalone on acetylcholine (ACh)-induced ionic channels were studied in voltage clamped 'myoballs' in culture. Alphaxalone produced a reversible blockade of the ACh-evoked inward current, ED50 = 6.0 microM. ⋯ In double pulse conditioning experiments, alphaxalone produced an additional inhibition with a time constant of recovery (550 ms) much longer than the time constant of recovery of the normal desensitization (250 ms). It was concluded that alphaxalone blocks active (open) ionic channels.
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Anesthesia progress · Jul 1984
Comparative StudyComparison of the effectiveness of etidocaine and lidocaine as local anesthetic agents during oral surgery.
In a double-blind study conducted in 112 patients undergoing removal of four impacted third molar teeth, etidocaine hydrochloride 1.5% solution with epinephrine 1:200,000 and lidocaine hydrochloride 2.0% solution with epinephrine 1:100,000 were used, one on each side of the face, to produce inferior alveolar nerve block, infiltration anesthesia of the maxillary tooth and hemostasis of the mucoperiosteum around each tooth. Surgically adequate anesthesia was rapidly produced by both agents but the duration of action of etidocaine was longer than that of lidocaine as reflected in more prolonged numbness of the lip and delayed onset of pain. Moreover, after etidocaine treatment fewer patients reported severe pain as the local anesthesia receded. No adverse local or systemic effects were observed in, or reported by, any of the patients.
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Biophysical journal · Jul 1984
Mechanisms of use-dependent block of sodium channels in excitable membranes by local anesthetics.
Many local anesthetics promote reduction in sodium current during repetitive stimulation of excitable membranes. Use-, frequency-, and voltage-dependent responses describe patterns of peak INa when pulse width, pulse frequency, and pulse amplitude are varied. Such responses can be viewed as reflecting voltage-sensitive shifts in equilibrium between conducting, unblocked channels and nonconducting, blocked channels. ⋯ We develop analytical expressions characterizing guarded receptors as "apparently" variable-affinity binding sites and predicting shifts in "apparent" channel inactivation in the hyperpolarizing direction. These results were confirmed with computer simulations. Furthermore, these results are in quantitative agreement with recent investigations of lidocaine binding in cardiac sodium channels.