Anesthesiology
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Cerebral blood flow (CBF) is rigorously regulated by various powerful mechanisms to safeguard the match between cerebral metabolic demand and supply. The question of how a change in cardiac output (CO) affects CBF is fundamental, because CBF is dependent on constantly receiving a significant proportion of CO. The authors reviewed the studies that investigated the association between CO and CBF in healthy volunteers and patients with chronic heart failure. ⋯ Given that CBF regulation is multifactorial but the various processes must exert their effects on the cerebral circulation simultaneously, the authors propose a conceptual framework that integrates the various CBF-regulating processes at the level of cerebral arteries/arterioles while still maintaining autoregulation. The clinical implications pertinent to the effect of CO on CBF are discussed. Outcome research relating to the management of CO and CBF in high-risk patients or during high-risk surgeries is needed.
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Observational Study
Visuospatial Ability as a Predictor of Novice Performance in Ultrasound-guided Regional Anesthesia.
Visuospatial ability correlates positively with novice performance of simple laparoscopic tasks. The aims of this study were to identify whether visuospatial ability could predict technical performance of an ultrasound-guided needle task by novice operators and to describe how emotional state, intelligence, and fear of failure impact on this. ⋯ An MRT predicts novice performance of an ultrasound-guided needling task on a turkey model and as a trait measure could be used as a tool to focus training resources on less-able individuals. Anxiety adversely affects performance. Therefore, both may prove useful in directing targeted training in ultrasound-guided regional anesthesia.
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Randomized Controlled Trial
Ultrasound Improves Cricothyrotomy Success in Cadavers with Poorly Defined Neck Anatomy: A Randomized Control Trial.
Misidentification of the cricothyroid membrane in a "cannot intubate-cannot oxygenate" situation can lead to failures and serious complications. The authors hypothesized that preprocedure ultrasound-guided identification of the cricothyroid membrane would reduce complications associated with cricothyrotomy. ⋯ Preprocedure ultrasound guidance in cadavers with poorly defined neck anatomy significantly reduces complications and improves correct insertion of the airway device in the cricothyroid membrane.
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Clinical Trial
Methadone Pharmacogenetics: CYP2B6 Polymorphisms Determine Plasma Concentrations, Clearance, and Metabolism.
Interindividual variability in methadone disposition remains unexplained, and methadone accidental overdose in pain therapy is a significant public health problem. Cytochrome P4502B6 (CYP2B6) is the principle determinant of clinical methadone elimination. The CYP2B6 gene is highly polymorphic, with several variant alleles. CYP2B6.6, the protein encoded by the CYP2B6*6 polymorphism, deficiently catalyzes methadone metabolism in vitro. This investigation determined the influence of CYP2B6*6, and other allelic variants encountered, on methadone concentrations, clearance, and metabolism. ⋯ CYP2B6 polymorphisms influence methadone plasma concentrations, because of altered methadone metabolism and thus clearance. Genetic influence is greater for oral than IV methadone and S- than R-methadone. CYP2B6 pharmacogenetics explains, in part, interindividual variability in methadone elimination. CYP2B6 genetic effects on methadone metabolism and clearance may identify subjects at risk for methadone toxicity and drug interactions.