Anesthesiology
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The purpose of this study was to determine current practice patterns for preoperative fasting at major pediatric hospitals. ⋯ There is no uniform fasting practice for children before elective surgery in the United States and Canada. However, there is agreement among most institutions that ingestion of clear fluids 2-3 h prior to general anesthesia is acceptable. Most also accept a 4-h restriction for breast milk and a 6-h restriction for nonhuman formula. There is great diversity among institutions regarding fasting for solids in children, with many restricting intake after midnight. There is little agreement about whether infant formula should be treated in the same way as solid food or how to categorize breast milk.
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The distribution of solutions injected into the epidural space has not been determined. The author therefore examined the site of catheter tips and the spread of contrast material in the epidural space using computed tomographic (CT) imaging in patients receiving successful epidural analgesia. ⋯ A variety of catheter tip positions and patterns of solution spread underlie normal epidural anesthesia. Nonuniform distribution of injectate is common and is compatible with uniform anesthesia. Posterior midline structures play a minimal role in impeding distribution of injectate. A far lateral catheter position is a more common cause of asymmetric block than anatomic barriers to solution spread.
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Cardiac output (CO) is likely to influence the pharmacokinetics of anesthetic drugs and should be accounted for in pharmacokinetic models. The influence of CO on the pharmacokinetic parameters of alfentanil in pigs was evaluated using compartmental and recirculatory models. ⋯ Cardiac output markedly influences the pharmacokinetics of alfentanil in pigs. Therefore, accounting for CO enhances the predictive value of pharmacokinetic models of alfentanil.