Anesthesiology
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The purpose of this study was to determine whether prior administration ritodrine worsens maternal hypotension during epidural anesthesia in gravid ewes. Twenty-four experiments were performed in nine chronically instrumented animals between 0.8 and 0.9 of timed gestation. The experimental sequence included the following: 1) at time-zero, intravenous (iv) administration of ritodrine, 0.004 mg.kg-1.min-1, or normal saline (NS) for 2 h; 2) at 120 min discontinuation of ritodrine, and administration of a 500 ml iv bolus of NS over 15 min; and 3) at 135 min epidural injection of 2% lidocaine or NS. ⋯ Cardiac output remained above baseline (P less than 0.01) after epidural injection of lidocaine in the ritodrine-lidocaine group. In contrast, in the NS-lidocaine group cardiac output was 13 +/- 5% below baseline (P = 0.005) at 150 min. Fetal arterial pH did not change significantly in either the ritodrine-lidocaine or ritodrine-NS group.(ABSTRACT TRUNCATED AT 250 WORDS)
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Etomidate is available in two different solvents: propylene glycol for induction of anesthesia and ethanol for maintenance of anesthesia. The direct effect of etomidate (1 and 5 micrograms/ml) and of its solvents on cardiac muscle was studied using rat left ventricular papillary muscle. Etomidate induced a slight positive inotropic effect in both solvents, as shown by an increase in maximum unloaded shortening velocity (Vmax) but not in force. ⋯ This suggests that propylene glycol was responsible for the decrease in SR function. Etomidate in propylene glycol thus has a dual action on rat myocardium: 1) a slight positive inotropic effect due to etomidate per se, and 2) a slight decrease in SR function probably related to propylene glycol. However, because etomidate in propylene glycol induced a slight decrease in isometric force under certain experimental conditions (i.e., after isometric stabilization), etomidate in propylene glycol may induce a slight negative inotropic effect in some clinical conditions as a result of its dual action on the myocardium.
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Biography Historical Article
Abel Lawrence Peirson: early proponent of etherization.
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Randomized Controlled Trial Clinical Trial
Efficacy of an epidural test dose in children anesthetized with halothane.
The effect of an intravenous (iv) injection of lidocaine with epinephrine was studied to determine if such a test dose would cause a reliably detectable increase in heart rate and systemic blood pressure in children anesthetized with halothane and nitrous oxide. The effect of the injection of atropine before the test dose on these parameters was also determined. Sixty-five children 1 month to 11 yr of age and weighing 3.9-35 kg were studied. ⋯ Following the iv test dose, 6 of 21 children in group 2 had an increase in heart rate of less than 10 beats/min, while only one child in group 1 had an increase in heart rate of less than 10 beats/min. Intravenous test doses that did not contain epinephrine (groups 3 and 4) had no effect on heart rate or blood pressure. Atropine, 10 micrograms/kg, improves the reliability of an epidural test dose in children anesthetized with halothane and nitrous oxide but does not ensure total reliability in detecting an intravascular injection.