Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Prospective examination of epidural catheter insertion.
Although it is generally accepted that inserting epidural catheters 3-4 cm into the epidural space minimizes complications, no prospective randomized examination of epidural catheter insertion length has been published. ⋯ Epidural catheters should be inserted either 2 cm when rapid labor is anticipated or 6 cm when prolonged labor or cesarean delivery is likely. Additionally, epidural catheters that result in intravenous cannulation or unilateral sensory analgesia can be manipulated effectively to provide analgesia for labor and delivery.
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Randomized Controlled Trial Comparative Study Clinical Trial
Cardiac outcome after peripheral vascular surgery. Comparison of general and regional anesthesia.
Despite evidence that regional anesthesia may be associated with fewer perioperative complications than general anesthesia, most studies that have compared cardiac outcome after general or regional anesthesia alone have not shown major differences. This study examines the impact of anesthetic choice on cardiac outcome in patients undergoing peripheral vascular surgery who have a high likelihood of associated coronary artery disease. ⋯ The choice of anesthesia, when delivered as described, does not significantly influence cardiac morbidity and overall mortality in patients undergoing peripheral vascular surgery.
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Randomized Controlled Trial Clinical Trial
Hemodynamic responses to intravascular injection of epinephrine-containing epidural test doses in adults during general anesthesia.
Epidural anesthesia is sometimes initiated during general anesthesia, yet few data exist concerning efficacy of epinephrine-containing test doses. ⋯ Hemodynamic responses to intravascular injection of test doses vary with dose of epinephrine and depth and type of general anesthetic used. Thus, the 15 micrograms epinephrine contained in the standard test dose may not be sufficient during all anesthetic conditions.
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Randomized Controlled Trial Comparative Study Clinical Trial
Propofol fails to attenuate the cardiovascular response to rapid increases in desflurane concentration.
A rapid increase in desflurane concentration to greater than 1 MAC transiently increases heart rate, arterial blood pressure, and circulating catecholamine concentration. Because propofol decreases sympathetic outflow, it was hypothesized that propofol would blunt these responses. ⋯ Although able to blunt the increase in epinephrine concentration, propofol 2 mg.kg-1 propofol does no attenuate the transient cardiovascular response to a rapid increase in desflurane concentration to greater than 1 MAC.
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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.