Local and regional anesthesia
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Epidural analgesia is an extremely effective and popular treatment for labor pain. In this review, we trace the history of the use of epidural analgesia and its refinements. ⋯ The incidence of side effects is low. Maintenance of analgesia that allows patient control enhances patient satisfaction.
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Ultrasound guided regional anesthesia (UGRA) for peripheral nerve blockade is becoming increasingly popular. The advantage of ultrasound technology is that it affords the anesthesiologist the real time ability to visualize neural structures, needle advancement, and local anesthetic spread. Recent data suggest that UGRA generates improved success rates and reductions in performance times in comparison to traditional approaches. ⋯ Given that UGRA requires a unique set of skills, formal standards and guidelines are currently being developed by leadership societies in order to foster education and training. This review article, in a case vignette format, highlights important techniques, concepts, and limitations regarding the use of ultrasound to facilitate regional anesthesia. Clinically relevant aspects of ultrasound physics are also discussed.
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With respect to the membrane lipid theory as a molecular mechanism for local anesthetics, two critical subjects, the negligible effects of charged drugs when applied extracellularly and the stereoselective effects of enantiomers, were verified by paying particular attention to membrane components, phospholipids with the anionic property, and cholesterol with several chiral carbons. The membrane interactivities of structurally-different anesthetics were determined by their induced fluidity changes of liposomal membranes. Lidocaine (3.0 μmol/mL) fluidized phosphatidylcholine membranes, but not its quaternary derivative QX-314 (3.0 μmol/mL). ⋯ However, their membrane effects were not different when removing cholesterol from the model membranes. Stereoselectivity is producible by cholesterol which increases the chirality of lipid bilayers and enables to discriminate anesthetic enantiomers. The membrane lipid interaction should be reevaluated as the mode of action of local anesthetics.