Anesthesiology
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Randomized Controlled Trial Clinical Trial
Cardiovascular and metabolic response to acute normovolemic anemia. Effects of anesthesia.
The maintenance of adequate tissue oxygenation during acute anemia depends on an increase in both cardiac output and tissue oxygen extraction. This study tested the hypothesis that anesthesia blunts the cardiac output response associated with acute normovolemic hemodilution. ⋯ Anesthesia significantly reduces the cardiac output response associated with ANH. This could be related to the effects of the anesthetic drugs on the autonomic and the cardiovascular systems.
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Comparative Study Clinical Trial
Evaluation of a cerebral oximeter as a monitor of cerebral ischemia during carotid endarterectomy.
Stroke is an important contributor to perioperative morbidity and mortality associated with carotid endarterectomy (CEA). This investigation was designed to compare the performance of the INVOS-3100 cerebral oximeter to neurologic function, as a means of detecting cerebral ischemia induced by carotid cross-clamping, in patients undergoing carotid endarterectomy with cervical plexus block. ⋯ Monitoring rSO2 with INVOS-3100 to detect cerebral ischemia during CEA has a high negative predictive value, but the positive predictive value is low.
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The lungs have been mentioned as a possible site contributing to the extrahepatic clearance of propofol. The objective of the present study was to clarify the pulmonary disposition of propofol directly in human lungs by investigating both the first-pass uptake and pulmonary extraction at pseudo-steady state. ⋯ Most of the propofol that undergoes pulmonary uptake during the first pass was released back to the circulation by back diffusion. Metabolism was not involved in the pulmonary uptake in human lungs.
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Approximate entropy, a measure of signal complexity and regularity, quantifies electroencephalogram changes during anesthesia. With increasing doses of anesthetics, burst-suppression patterns occur. Because of the high-frequency bursts, spectrally based parameters such as median electroencephalogram frequency and spectral edge frequency 95 do not decrease, incorrectly suggesting lightening of anesthesia. The authors investigated whether the approximate entropy algorithm correctly classifies the occurrence of burst suppression as deepening of anesthesia. ⋯ Electroencephalogram approximate entropy, but not electroencephalogram median frequency or spectral edge frequency 95 without burst compensation, correctly classifies the occurrence of burst-suppression pattern as increasing anesthetic drug effect.