Anesthesiology
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Randomized Controlled Trial Clinical Trial
Prophylactic atenolol reduces postoperative myocardial ischemia. McSPI Research Group.
Perioperative myocardial ischemia occurs in 20-40% of patients at risk for cardiac complications and is associated with a ninefold increase in risk for perioperative cardiac death, myocardial infarction, or unstable angina, and a twofold long-term risk. Perioperative atenolol administration reduces the risk of death for as long as 2 yr after surgery. This randomized, placebo-controlled, double-blinded trial tested the hypothesis that perioperative atenolol administration reduces the incidence and severity of perioperative myocardial ischemia, potentially explaining the observed reduction in the risk for death. ⋯ Perioperative administration of atenolol for 1 week to patients at high risk for coronary artery disease significantly reduces the incidence of postoperative myocardial ischemia. Reductions in perioperative myocardial ischemia are associated with reductions in the risk for death at 2 yr.
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It has been proposed that the measure of noxious stimulus-induced Fos (the protein product of the immediate early gene c-fos) expression in the spinal cord dorsal horn of laboratory animals may provide an estimate of the potential of specific treatments to produce preemptive analgesia. The present study examined this hypothesis by comparing the effects of intrathecal lidocaine given before and after hindpaw formalin injection on persistent nociceptive responses and Fos expression in spinal cord dorsal horn of rats. ⋯ The finding that persistent nociceptive behaviors and Fos expression were suppressed by intrathecal lidocaine pretreatment suggests that nociception in the second phase of the formalin test depends on increases in central hyperexcitability generated during the first phase. On the other hand, the finding that the intrathecal injection of lidocaine after formalin treatment reduced Fos expression but not nociceptive responses indicates an uncoupling of the behavioral and Fos protein responses to formalin and suggests that changes in Fos expression may not be a good predictor of the ability of agents to produce preemptive analgesia.
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It is not known whether inverse I:E ratio ventilation (IRV) offers any real benefit over conventional mechanical ventilation with positive end-expiratory pressure (CMV-PEEP) at similar levels of end-expiratory pressure. ⋯ Short-term PC-IRV improved carbon dioxide clearance, but the lung became less efficient as an oxygen exchanger. Furthermore, based on mean airway and plateau pressures, the risk of barotrauma was not reduced with this type of ventilation.
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Randomized Controlled Trial Clinical Trial
Psychedelic effects of ketamine in healthy volunteers: relationship to steady-state plasma concentrations.
Ketamine has been associated with a unique spectrum of subjective "psychedelic" effects in patients emerging from anesthesia. This study quantified these effects of ketamine and related them to steady-state plasma concentrations. ⋯ Subanesthetic doses of ketamine produce psychedelic effects in healthy volunteers. The relation between steady-state venous plasma ketamine concentrations and effects is highly linear between 50 and 200 ng/ml.