Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Arrhythmogenic doses of epinephrine are similar during desflurane or isoflurane anesthesia in humans.
Inhaled anesthetics can alter the arrhythmogenicity of exogenously administered epinephrine. Although swine anesthetized with desflurane or isoflurane do not differ in their arrhythmic response to exogenous epinephrine, the relative effect of epinephrine in the presence of these anesthetics in humans is untested. ⋯ The authors concluded that isoflurane and desflurane do not differ in their sensitization of human myocardium to the arrhythmogenic effects of exogenously administered epinephrine.
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Randomized Controlled Trial Clinical Trial
The dose of propofol required to prevent children from moving during magnetic resonance imaging.
Intravenous propofol offers several advantages as an anesthetic for children undergoing magnetic resonance imaging. However, the dose of propofol required to prevent movement during magnetic resonance imaging is likely to be less than that required for surgical anesthesia. ⋯ Following induction of anesthesia with halothane, nitrous oxide, and a 2 mg.kg-1 loading dose of propofol, infusion of propofol at a rate of 100 micrograms.kg-1 x min-1 effectively prevents children from moving during elective magnetic resonance imaging. A transient decrease in arterial oxygen saturation can occur after the initial bolus of propofol. Recovery from anesthesia is rapid and without nausea or vomiting.
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Previous studies have shown that desflurane and isoflurane produce similar hemodynamic actions. This investigation examined the cardiovascular effects of desflurane and isoflurane in the presence or absence of dexmedetomidine, a highly selective alpha 2-adrenergic agonist that may be clinically useful as a premedicant or anesthetic adjuvant. ⋯ The results indicate that the cardiovascular actions of desflurane or isoflurane are similar in the absence or presence of dexmedetomidine; however, some differences between anesthetic groups were noted. In the presence of dexmedetomidine, systemic vascular resistance during desflurane anesthesia was higher when compared with that during isoflurane anesthesia, indicating that desflurane produces less pronounced direct effects on peripheral vascular tone. The concomitant greater reductions in cardiac output are consistent with greater impedance to left ventricular outflow in desflurane-anesthetized dogs pretreated with dexmedetomidine, because no differences in contractile function were observed between volatile anesthetics. In contrast, cardiac output during isoflurane anesthesia after pretreatment with oral dexmedetomidine is better maintained secondary to the peripheral vasodilator actions of this agent.
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Cardioplegia is used to protect the myocardium from ischemic injury during open-heart surgery. However, the delivery of cardioplegic solutions may be impaired by anatomic and/or functional conditions, such as the development of transient aortic regurgitation during antegrade administration of cardioplegia or shunting through a foramen ovale during retrograde administration. In this study, the authors used a new method of cardioplegia administration, based on intraoperative contrast echocardiography, to detect on-line causes of inadequate cardioplegia delivery. ⋯ This study shows that incomplete myocardial distribution of cardioplegia, secondary to transient aortic valve incompetence or shunting through the foramen ovale, is not uncommon in patients undergoing coronary surgery.
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Respiratory distress syndrome carries a high morbidity and mortality when treated with mechanical ventilation with positive end-expiratory pressure. Perfluorocarbon liquids are employed in liquid ventilation due to low surface tension and high gas solubility. To assess whether intratracheal administration of the perfluorocarbon, perflubron, in combination with conventional mechanical ventilation could be of therapeutic benefit in respiratory distress syndrome, the authors tested the effects of different doses of intratracheal perflubron administration on gas exchange and lung mechanics in adult animals with respiratory failure during a 6-h observation period. ⋯ The results of this study imply that there is no association between the lung mechanics and gas exchange parameters for mechanical ventilation in combination with intratracheal perfluorocarbon administration. The data suggest that this type of perfluorocarbon administration with conventional mechanical ventilation offers a simple, alternative treatment of respiratory distress syndrome. With this technique, adequate pulmonary gas exchange can be maintained at relatively low airway pressures with high perfluorocarbon doses for several hours.