Articles: anesthetics.
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Obstet Gynecol Surv · Mar 1984
ReviewGeneral anesthesia in cesarean section: effect on mother and neonate.
Advances in anesthetic techniques during the past several decades have resulted in an excellent outcome in infants delivered by cesarean section under general anesthesia. To understand these results, it is important to be familiar with the physiologic changes which occur during general anesthesia. A review of the literature which focuses on the findings which led to current anesthetic principles is presented.
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Molecular pharmacology · Mar 1984
Inhibition of binding of [3H]batrachotoxinin A 20-alpha-benzoate to sodium channels by local anesthetics.
The effects of several local anesthetics on the binding of ligands to receptors associated with voltage-sensitive sodium channels in rat brain synaptosomes have been examined. In the presence of 0.3 microM scorpion toxin, the 13 local anesthetics tested inhibited the specific binding of [3H]batrachotoxinin A 20 alpha-benzoate [( 3H]BTX-B), a ligand which binds to a receptor site responsible for the activation of sodium channel ion flux, in a dose-dependent fashion, with KD values ranging from 1.2 microM for tetracaine to 1.58 mM for benzocaine. A plot of log KD from these binding experiments against log K0.5 for inhibition of sodium currents by local anesthetics from electrophysiological experiments yielded a regression line with a slope of 0.84 and a correlation coefficient, r, of 0.86, demonstrating that the inhibition of [3H]BTX-B binding by local anesthetics occurs within a concentration range of physiological relevance. ⋯ Analysis of the effects of local anesthetics in terms of an allosteric model of drug action showed that they bind to inactive states of sodium channels with at least a 10-fold higher affinity than active states. A 7-fold difference in KD for inhibition of [3H]BTX-B binding between the local anesthetic stereoisomers RAC 109 I and RAC 109 II was observed. Similarly, the dissociation rate constant for the [3H]BTX-B/receptor complex was increased 9.3-fold in the presence of RAC 109 II and 4.3-fold in the presence of a comparable concentration of RAC 109 I.(ABSTRACT TRUNCATED AT 250 WORDS)
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Acta Anaesthesiol Scand · Feb 1984
Caudal anaesthesia for upper abdominal surgery in infants and children: a simple calculation of the volume of local anaesthetic.
Where the use of non-depolarizing muscle relaxants and antagonists is undesirable in infants and children undergoing abdominal surgery, caudal anaesthesia is frequently adopted, combined with light general anaesthesia. A simple calculation has been derived to determine the volume of local anaesthetic needed to obtain a higher effective anaesthetic level (up to T4-5) for upper abdominal operations using caudal anaesthesia. ⋯ A similar relationship was also demonstrated radiographically in 16 cadavers by studying the spread of radio-opaque solution in the epidural space introduced by the caudal technique. From both statistical studies, a simple formula to determine the required volume of local anaesthetic for upper abdominal surgery was derived: V = D-13, where V is the volume of local anaesthetic in ml and D is the distance from C7 to the sacral hiatus in cm.
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Measurements of the vapour concentrations delivered by the EMO and Oxford Miniature Vaporizers (OMV) were made with both continuous (plenum mode) and intermittent (drawover mode) air flows. Leakage of ether, halothane and trichloroethylene vapours through the corrugated elephant tubing was also measured. Both vaporizers performed most consistently with the intermittent flows for which they were designed. ⋯ Minimal amounts of ether were lost through the tubing but halothane losses were appreciable, while losses of trichloroethylene were enough to reduce the concentrations available to the patient. The EMO is not suitable for plenum use with carrier gas flows below about 10 litres/min. The OMV is a useful plenum vaporizer although the outputs are generally lower than indicated at higher flows.