Articles: anesthetics.
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Fifty-three infants with neural tube defects and 97 with other major congenital abnormalities have been reviewed. In only one case did the mother receive an anaesthetic before or during pregnancy and this anaesthetic is unlikely to have played any part in the outcome. The anaesthetic history was recorded for 471 mothers who booked consecutively for their confinements. ⋯ The corrected annual incidence of anaesthesia was about 20% (14% related to fertility). There were no fetal abnormalities, but two miscarriages in the women anaesthetized during pregnancy. There was one abnormal baby delivered to a women anaesthetized more than 12 weeks before the last menstrual period.
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In order to test the requirement of Na channel inactivation for the action of local anesthetics, we investigated the inhibitory effects of quaternary and tertiary amine anesthetics on normally inactivating and noninactivating Na currents in squid axons under voltage clamp. Either the enzymatic mixture pronase, or chloramine-T (CT), a noncleaving, oxidizing reagent, was used to abolish Na channel inactivation. We found that both the local anesthetics QX-314 and etidocaine, when perfused internally at 1 mM, elicited a "tonic" (resting) block of Na currents, a "time-dependent" block that increased during single depolarizations, and a "use-dependent" (phasic) block that accumulated as a result of repetitive depolarizations. ⋯ The voltage dependence of the steady state phasic block in CT-treated axons differed from that in the controls; an 8-10% reduction of the maximum phasic block and a steepening and shift of the voltage dependence in the hyperpolarizing direction resulted from CT treatment. The results show that these anesthetics can bind rapidly to open Na channels in a voltage-dependent manner, with no requirement for fast inactivation. We propose that the rapid phasic blocking reactions in nerve are consequences primarily of channel activation, mediated by binding of anesthetics to open channels, and that the voltage dependence of phasic block arises directly from that of channel activation.
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Comparative Study Clinical Trial Controlled Clinical Trial
The minimum alveolar concentration (MAC) of sevoflurane in humans.
Forty surgical patients were divided into two groups and anesthetized with either sevoflurane and oxygen or sevoflurane, oxygen, and nitrous oxide. The minimum alveolar concentration (MAC) for sevoflurane required to prevent movement in response to surgical incision in healthy patients was 1.71 +/- 0.07% (SE). ⋯ The reduction in sevoflurane MAC was 61.4%. The AD95 for sevoflurane with 63.5% end-tidal nitrous oxide was 0.94%.
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Randomized Controlled Trial Comparative Study Clinical Trial
Anaesthesia for evacuation of retained products of conception. Comparison between alfentanil plus etomidate and fentanyl plus thiopentone.
Forty-four patients presenting for evacuation of retained products of conception were anaesthetized with either fentanyl and thiopentone, or alfentanil with etomidate, along with 70% nitrous oxide in oxygen. There was no difference between the two techniques in indices of immediate recovery (time to opening eyes and obeying a simple command), but the rate of return of higher mental functions (assessed by a coin counting test) was significantly better using the alfentanil-etomidate technique. There was no statistically significant difference between the techniques for apnoea or abnormal movements during anaesthesia, but alfentanil with etomidate was associated with significantly more pain on injection and a higher frequency of postoperative vomiting (40%).