Anesthesiology
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Randomized Controlled Trial
Placental transfer and fetal metabolic effects of phenylephrine and ephedrine during spinal anesthesia for cesarean delivery.
Use of ephedrine in obstetric patients is associated with depression of fetal acid-base status. The authors hypothesized that the mechanism underlying this is transfer of ephedrine across the placenta and stimulation of metabolism in the fetus. ⋯ Ephedrine crosses the placenta to a greater extent and undergoes less early metabolism and/or redistribution in the fetus compared with phenylephrine. The associated increased fetal concentrations of lactate, glucose, and catecholamines support the hypothesis that depression of fetal pH and base excess with ephedrine is related to metabolic effects secondary to stimulation of fetal beta-adrenergic receptors. Despite historical evidence suggesting uteroplacental blood flow may be better maintained with ephedrine, the overall effect of the vasopressors on fetal oxygen supply and demand balance may favor phenylephrine.
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Randomized Controlled Trial Comparative Study
Preserved memory function during bispectral index-guided anesthesia with sevoflurane for major orthopedic surgery.
Memory function under anesthesia is undesired but may arise from light hypnosis as well as stress-enhanced learning during surgery. The bispectral index (BIS, Aspect Medical Systems, Norwood, MA) is a monitor of hypnotic state that can help to avoid light hypnosis (i.e., BIS above 60). This study tested the hypothesis that BIS-guided anesthesia maintaining BIS 50-60 reduces the likelihood of memory function under anesthesia. ⋯ BIS titration to BIS 50-60 does not necessarily curb memory function under anesthesia when BIS values higher than 60 occur. Preoperative analgesia attenuated the likelihood of memory function under anesthesia.
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BACKGROUNDPostoperative pain Is an independent predictor of postoperative delirium. Whether postoperative delirium limits patient-controlled analgesia (PCA) use has not been determined. ⋯ Postoperative delirium did not limit PCA use. Despite more opioid use, visual analog scale scores were higher in patients with delirium. Future studies on delirium should consider the role of pain and pain management as potential etiologic factors.
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Clinical Trial
Monitoring electrical skin conductance: a tool for the assessment of postoperative pain in children?
Monitoring changes in electrical skin conductance has been described as a potentially useful tool for the detection of acute pain in adults. The aim of this study was to test the method in pediatric patients. ⋯ NFSC accurately predicted the absence of moderate to severe pain in postoperative pediatric patients. The measurement of NFSC may therefore provide an additional tool for pain assessment in this group of patients. However, more research is needed to prospectively investigate the observations made in this study and to determine the clinical applicability of the method.
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Obtaining accurate end-tidal carbon dioxide pressure measurements via nasal cannula poses difficulties in postanesthesia patients who are mouth breathers, including those who are obese and those with obstructive sleep apnea (OSA); a nasal cannula with an oral guide may improve measurement accuracy in these patients. The authors evaluated the accuracy of a mainstream capnometer with an oral guide nasal cannula and a sidestream capnometer with a nasal cannula that did or did not incorporate an oral guide in spontaneously breathing non-obese patients and obese patients with and without OSA during recovery from general anesthesia. ⋯ Mainstream capnometry performed best, and an oral guide improved the performance of sidestream capnometry. Accuracy in non-obese and obese patients, with and without OSA, was similar.