Anesthesiology
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Randomized Controlled Trial Clinical Trial
Does epidural anesthesia have general anesthetic effects? A prospective, randomized, double-blind, placebo-controlled trial.
Clinically, patients require surprisingly low end-tidal concentrations of volatile agents during combined epidural-general anesthesia. Neuraxial anesthesia exhibits sedative properties that may reduce requirements for general anesthesia. The authors tested whether epidural lidocaine reduces volatile anesthetic requirements as measured by the minimum alveolar concentration (MAC) of sevoflurane for noxious testing cephalad to the sensory block. ⋯ Lidocaine epidural anesthesia reduced the MAC of sevoflurane by approximately 50%. This MAC sparing is most likely caused by indirect central effects of spinal deafferentation and not to systemic effects of lidocaine or direct neural blockade. Thus, lower concentrations of volatile agents than those based on standard MAC values may be adequate during combined epidural-general anesthesia.
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Randomized Controlled Trial Clinical Trial
Effect of the duration of electrical stimulation on the analgesic response in patients with low back pain.
Electrical stimulation of peripheral nerves produces acute analgesic effects. This randomized, sham-controlled, crossover study was designed to evaluate the effect of differing durations of electrical stimulation on the analgesic response to percutaneous electrical nerve stimulation in 75 consenting patients with low back pain. ⋯ The recommended duration of electrical stimulation with percutaneous electrical nerve stimulation therapy is 30 min.
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Randomized Controlled Trial Clinical Trial
Epileptiform electroencephalogram during mask induction of anesthesia with sevoflurane.
Sevoflurane is suggested as a suitable anesthetic agent for mask induction in adults. The authors recently found that hyperventilation during sevoflurane-nitrous oxide-oxygen mask induction is associated with cardiovascular hyperdynamic response. We tested the hypothesis that the hyperdynamic response can be explained by electroencephalography (EEG) findings. ⋯ Sevoflurane mask induction elicits epileptiform EEG patterns. These are associated with an increase in heart rate in patients with controlled hyperventilation and also during spontaneous breathing of sevoflurane.
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Randomized Controlled Trial Clinical Trial
Beneficial effects from beta-adrenergic blockade in elderly patients undergoing noncardiac surgery.
Perioperative beta-blockade has been shown to improve long-term cardiac outcome in noncardiac surgical patients. A possible mechanism for the reduced risk of perioperative myocardial infarction is the attenuation of the excitotoxic effects of catecholamine surges by beta-blockade. It was hypothesized that beta-blocker-induced alteration of the stress response was responsible for the reported improvements in cardiovascular outcome. Several variables associated with the perioperative use of beta-blockade were also evaluated. ⋯ Beta-blockade does not reduce the neuroendocrine stress response, suggesting that this mechanism is not responsible for the previously reported improved cardiovascular outcome. However, it confers several advantages, including decreased analgesic requirements, faster recovery from anesthesia, and improved hemodynamic stability. The release of cardiac troponin I suggests the occurrence of perioperative myocardial damage in this elderly population, which appears to be independent of the neuroendocrine stress response.
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Randomized Controlled Trial Clinical Trial
Effect of dobutamine on splanchnic carbohydrate metabolism and amino acid balance after cardiac surgery.
As a predominant beta-adrenergic agonist, dobutamine may modify blood flow distribution and increase metabolic demands. The authors investigated the effect of a dobutamine-induced increase in cardiac output on splanchnic and femoral blood flow and metabolism in patients after cardiac surgery. ⋯ After coronary artery bypass surgery, dobutamine increased systemic and regional blood flow and decreased systemic and regional oxygen extraction. Dobutamine did not affect splanchnic glucose production or lactate or amino acid balance. This suggests that dobutamine increases splanchnic blood flow without a concomitant increase in hepatosplanchnic metabolism.