Anesthesiology
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Randomized Controlled Trial Clinical Trial
Sole use of dexmedetomidine has limited utility for conscious sedation during outpatient colonoscopy.
This study evaluated the ability of dexmedetomidine to provide analgesia and sedation for outpatient colonoscopy, examining outcomes including cardiorespiratory variables, side effects, and discharge readiness. ⋯ The use of dexmedetomidine to provide analgesia/sedation for colonoscopy is limited by distressing side effects, pronounced hemodynamic instability, prolonged recovery, and a complicated administration regimen.
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Mechanical ventilation induces cyclic changes in vena cava blood flow, pulmonary artery blood flow, and aortic blood flow. At the bedside, respiratory changes in aortic blood flow are reflected by "swings" in blood pressure whose magnitude is highly dependent on volume status. ⋯ That is, these studies have demonstrated the value of this physical sign in answering one of the most common clinical questions, Can we use fluid to improve hemodynamics?, while static indicators of cardiac preload (cardiac filling pressures but also cardiac dimensions) are frequently unable to correctly answer this crucial question. The reliable analysis of respiratory changes in arterial pressure is possible in most patients undergoing surgery and in critically ill patients who are sedated and mechanically ventilated with conventional tidal volumes.
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Animal studies have demonstrated neuroprotective properties of S-ketamine, but its effects on cerebral blood flow (CBF), metabolic rate of oxygen (CMRO2), and glucose metabolic rate (GMR) have not been comprehensively studied in humans. ⋯ S-ketamine-induced CBF increases exceeded the minor changes in CMRO2 and GMR during anesthesia.
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Normoxic and hypoxic ventilation are influenced by chemoreceptor and nonchemoreceptor drives. Although inhalational anesthetics blunt hypoxic ventilation, this effect is reversed by audiovisual stimulation but not by pain. Opioids reduce both normoxic and hypoxic ventilation, but their interaction with pain and audiovisual stimulation has not been fully reported. ⋯ The computer game was a more potent stimulus than pain in countering the depressant effect of remifentanil on AHR. Although the effect of high wakefulness was more attenuated than was previously observed with respect to inhalational anesthetics, the significance of these findings is underlined by the more clinically relevant scenario of what is experienced in the face of opioid administration.
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The authors tested the hypothesis that adenosine receptors in polymorphonuclear neutrophils and the heart mediate the preconditioning effects of volatile anesthetics against neutrophil-induced contractile dysfunction. ⋯ An activation of adenosine receptors in neutrophils, but not in the heart, plays a role in the preconditioning effects of volatile anesthetics against neutrophil-induced contractile dysfunction.