Anesthesiology
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Methoxyflurane nephrotoxicity results from its metabolism, which occurs by both dechlorination (to methoxydifluoroacetic acid [MDFA]) and O-demethylation (to fluoride and dichloroacetic acid [DCAA]). Inorganic fluoride can be toxic, but it remains unknown why other anesthetics, commensurately increasing systemic fluoride concentrations, are not toxic. Fluoride is one of many methoxyflurane metabolites and may itself cause toxicity and/or reflect formation of other toxic metabolite(s). This investigation evaluated the disposition and renal effects of known methoxyflurane metabolites. ⋯ Methoxyflurane nephrotoxicity seems to result from O-demethylation, which forms both fluoride and DCAA. Because their co-formation is unique to methoxyflurane compared with other volatile anesthetics and they are more toxic than fluoride alone, this suggests a new hypothesis of methoxyflurane nephrotoxicity. This may explain why increased fluoride formation from methoxyflurane, but not other anesthetics, is associated with toxicity. These results may have implications for the interpretation of clinical anesthetic defluorination, use of volatile anesthetics, and the laboratory methods used to evaluate potential anesthetic toxicity.
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In children with a history of significant obstructive sleep apnea who undergo adenotonsillectomy, postsurgical administration of opiates has been alleged to be associated with an increased risk for respiratory complications, including respiratory depression. The authors hypothesize that this association is due to an effect of recurrent hypoxemia that accompanies more severe obstructive sleep apnea on altered responsiveness to subsequent exogenous opiates. ⋯ Previous recurrent hypoxia increases respiratory sensitivity to subsequent opiate agonists. If these findings are applicable to humans, opiate dosing in children must be adjusted depending on history of recurrent hypoxemia to avoid respiratory depression.
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Persistent chest pain may originate from cardiac surgery. Conflicting results have been reported on the incidence of persistent poststernotomy pain with considerable discrepancies between the retrospective reports and the one prospective study conducted to assess this pain. Therefore, the authors conducted a follow-up survey for the first 12 months after cardiac surgery in 213 patients who had a sternotomy. ⋯ Although common, the incidence of persistent pain after sternotomy was lower than previously reported. Also, reassuringly, 1 year after surgery this pain was mostly mild in nature both at rest and on movement.
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Comparative Study Clinical Trial
Quantifying the effect of antiplatelet therapy: a comparison of the platelet function analyzer (PFA-100) and modified thromboelastography (mTEG) with light transmission platelet aggregometry.
Antiplatelet therapy with aspirin and clopidogrel is known to confer protection against ischemic events. Increasing numbers of patients are presenting for surgery while taking these drugs. This may lead to an increase in perioperative blood loss, particularly in those who have a heightened response to the drugs. Identifying these patients preoperatively would allow us to plan appropriate management. ⋯ The search for a point-of-care monitor of platelet function has been the focus of much research. This study has shown that the modified thromboelastograph can be used for monitoring the effect of clopidogrel as well as aspirin. It potentially has a wide scope to be used for the monitoring of effectiveness of therapy as well as a possible predictor of perioperative bleeding.