Anesthesiology
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Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle, manifested as a life-threatening hypermetabolic crisis after exposure to anesthetics. Type I ryanodine receptor 1 is the primary gene responsible for susceptibility to MH as well as central core disease, a congenital myopathy that predisposes susceptibility to MH. More than 40 mutations in the RyR1 gene cluster in three coding regions: the N-terminus, central, and C-terminus regions. However, the frequency of mutations in each region has not been studied in the North American MH-susceptible population. ⋯ The detection rate for mutations is only 23% by screening mutations (or exons) listed in the 2002 North American consensus panel. The implications from this study suggest that testing the central region first is currently the most effective screening strategy for the North American population. Screening more exons in the three hot spots may be needed to find an accurate frequency of mutations in the RyR1 gene.
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The pharmacokinetic and pharmacodynamic characteristics of opioids vary throughout the day, as demonstrated for oral morphine in chronic pain. However, little is known about the chronobiology of intrathecal lipid soluble opioids used for labor analgesia. The aim of this prospective study was to determine whether the duration of action of intrathecally administered sufentanil is influenced by the time of administration. ⋯ The duration of intrathecal sufentanil analgesia exhibited a temporal pattern with 30% variations throughout the day period. The authors point out that the lack of consideration of chronobiological conditions in intrathecally administered analgesia studies can cause significant statistical bias. Further studies dealing with intrathecal opioids should consider the time of drug administration.
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Central neuraxial blockades find widespread applications. Severe complications are believed to be extremely rare, but the incidence is probably underestimated. ⋯ : More complications than expected were found, probably as a result of the comprehensive study design. Half of the complications were retrieved exclusively from administrative files. Complications occur significantly more often after epidural blockade than after spinal blockade, and the complications are different. Obstetric patients carry significantly lower incidence of complications. Osteoporosis is proposed as a previously neglected risk factor. Close surveillance after central neuraxial blockade is mandatory for safe practice.
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Comparative Study
Comparative effects of bupivacaine and ropivacaine on intracellular calcium transients and tension in ferret ventricular muscle.
Recent evidence suggests that ropivacaine exerts markedly less cardiotoxicity compared with bupivacaine; however, the mechanisms are not fully understood at the molecular level. ⋯ The cardiodepressant effect of bupivacaine is approximately twofold greater than that of ropivacaine. Bupivacaine suppresses Ca transients more markedly than does ropivacaine and reduces myofibrillar activation, which may at least in part underlie the greater inhibitory effect of bupivacaine on cardiac contractions. These results suggest that ropivacaine has a more favorable profile as a local anesthetic in the clinical settings.
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The Texas Medicaid Program (Medicaid) defines billable time for labor analgesia as face-to-face time; therefore, anesthesia providers determine billed time. The authors' goal was to determine the influence of anesthesia providers on labor analgesia costs billed to Medicaid. ⋯ The costs of labor analgesia billed to Texas Medicaid were 19% to 26% less per patient when provided by anesthesiologists than by CRNAs, despite lower per-unit reimbursement of CRNAs.