Articles: anesthetics.
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Clinical Trial Controlled Clinical Trial
Heated humidification in major abdominal surgery.
The influence of heated humidification on body temperature and postoperative shivering was studied in 30 patients undergoing major intra-abdominal surgery. In the control group (I) the anaesthetic gases, administered in a non-rebreathing system, were humidified by a sponge heat and moisture exchanger. In group II the gases were humidified and heated to 37 degrees C and in group III up to 40 degrees C. ⋯ A good correlation was found between heat gain during the first hour of recovery, the feeling of cold and intensity of shivering. Intraoperative heat loss was minimal in all groups. Heated humidification had no statistically significant effect on the body temperatures or postoperative shivering and thus provided no additional advantage compared to the control group.
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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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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.
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Local anesthetics are the most widely used drugs in dentistry today. Knowledge of the pharmacology and toxicology of these agents will result in their intelligent and judicious use. The choice of local anesthetic should be individualized for each patient. ⋯ Occasionally, a clinician may be unsuccessful at achieving regional anesthesia despite these additional measures. Highly anxious dental patients or patients with a genuine tolerance to local anesthetics normally pose the most problems. Transitional block or threshold block phenomena should also be suspected in these situations.(ABSTRACT TRUNCATED AT 400 WORDS)