Anesthesiology
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Use of long-acting local anesthetics that elicit complete neural blockade for more than 3 h often is desirable in pain management. Unfortunately, clinically available local anesthetics are in general not suitable for prolonged analgesia. This report describes the organic synthesis and functional testing of a lidocaine derivative that appears to fulfill the criteria of long-acting local anesthetics. ⋯ In an attempt to elicit prolonged local anesthesia, a quaternary ammonium derivative of lidocaine containing a permanent charge and an additional hydrophobic component was synthesized. Complete sciatic neural blockade of more than 3 h was achieved with this derivative. Of note, sensory blockade was prolonged to a greater extent than motor blockade. The approach used in this study may prove useful for developing new drugs applicable in pain management.
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Randomized Controlled Trial Clinical Trial
Effects of storage time on quantitative and qualitative platelet function after transfusion.
Platelet transfusions are being used increasingly in patients with thrombocytopenia to improve hemostatic function before surgery and invasive procedures. However, there are limited data on the immediate quantitative and qualitative platelet response after transfusion. Some authors have suggested that transfused platelets require time in vivo to regain maximal function, which is dependent on the duration of platelet storage. Therefore, the timing of surgery and invasive procedures with optimal platelet function may not be occurring. ⋯ In patients with chemotherapy-induced thrombocytopenia, platelet transfusion causes an immediate increase in number and function, which is independent of storage time. This quantitative and qualitative increase persists unchanged for 2 h after transfusion, suggesting that there is no acute "warm-up-time" necessary for transfused platelets to regain maximal function. Fresh platelets demonstrate increased aggregation and dense granule release compared to 4-day stored platelets and may impart improved hemostatic function in vivo.
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Propofol reduces cerebral blood flow, cerebral metabolic rate for oxygen, and intracranial pressure and is being increasingly used in neuroanesthesia. In vivo studies have yielded conflicting results on its ability to protect against ischemic brain damage. In the current study, an in vitro model was used to examine the mechanism of propofol's action on anoxic neuronal transmission damage. ⋯ Propofol improved electrophysiologic recovery from anoxia during hyperthermia but not normothermia. At 37 degrees C propofol attenuated the changes in ATP, Na, and Ca, however, this did not result in improved recovery. At 39 degrees C the changes in ATP, Na, and K caused by anoxia were greater than at 37 degrees C; this could explain why electrophysiologic damage was worsened. Improved recovery with propofol at 39 degrees C may be explained by its attenuation of the changes in Ca, Na, and K at this temperature. The decrease in ATP was attenuated by both propofol and intralipid and therefore cannot explain the improved recovery.
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Randomized Controlled Trial Clinical Trial
Desflurane slightly increases the sweating threshold but produces marked, nonlinear decreases in the vasoconstriction and shivering thresholds.
Shivering is rare during general anesthesia. This observation suggests that anesthetics profoundly impair shivering. However, the effects of surgical doses of volatile anesthetics on control of shivering have yet to be evaluated. Furthermore, the effects of desflurane on sweating and thermoregulatory vasoconstriction remain unknown. Accordingly, the authors determined the concentration-dependent effects of desflurane on sweating, vasoconstriction, and shivering. ⋯ The observed linear increase in the sweating threshold was similar in pattern and magnitude to that produced by most general anesthetics. The approximately 3 degrees C reduction in the vasoconstriction threshold by 0.8 MAC desflurane was similar to that observed previously during isoflurane and propofol anesthesia. However, the threshold was reduced less than expected at 0.5 MAC, suggesting that the dose-response relationship for vasoconstriction is nonlinear. Shivering was induced without difficulty in this study although the response is rare in surgical patients. It is likely that shivering during general anesthesia is rare because thermoregulatory vasoconstriction usually prevents body temperature from decreasing the required additional 1-1.5 degrees C.