Articles: anesthetics.
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Anesthesia and analgesia · Dec 1982
Comparative StudyA comparative in vivo study of local neurotoxicity of lidocaine, bupivacaine, 2-chloroprocaine, and a mixture of 2-chloroprocaine and bupivacaine.
This study was undertaken because of several recent reports of adverse neurologic reactions following the use of 2-chloroprocaine. Carotid sheaths containing undisturbed vagus nerve were surgically exposed in rabbits and bathed in situ for up to 1 hour in one of the following-isotonic solutions: physiologic salt solution, lidocaine 2%, bupivacaine 0.75%, 2-chloroprocaine 3%, or a mixture of 2-chloroprocaine 1.5% and bupivacaine 0.375%. Each solution contained epinephrine, 5 micrograms/ml, (1:200,000). ⋯ Histologic sections revealed the presence of epineurial cellular infiltration and fibrosis, perineurial fibrosis, and axonal degeneration in nerves that had been exposed to 2-chloroprocaine or the mixture of 2-chloroprocaine and bupivacaine. Histologic abnormalities were minor or absent following exposure to lidocaine, to bupivacaine, or to physiologic salt solution. These findings suggest that, under the conditions of the experiments, 2-chloroprocaine is more neurotoxic than lidocaine or bupivacaine.
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Infusion rates for fentanyl were calculated to produce stable plasma concentrations at which the ability of fentanyl to reduce enflurane MAC could be studied utilizing the tail clamp method and measurement of end-tidal enflurane. Following the determination of control enflurane MAC in each animal, an infusion of fentanyl was begun. Group 1 received continuous successive infusion rates of 0.05, 0.1, and 0.2 micrograms . kg-1 . min-1 with respective loading doses (given over 20 min) of 15, 15, and 30 micrograms/kg; Group 2 received infusions of 0.2, 0.8, and 3.2 micrograms . kg-1 . min-1 with loading doses of 30, 90, and 270 micrograms/kg, respectively. ⋯ A threefold higher concentration produced a minimal further reduction. In Group 3 dogs, no change in enflurane MAC was seen. It was concluded that predictable, stable levels of fentanyl in plasma can be achieved, that there is a close relationship between the concentration of fentanyl in plasma and its enflurane sparing effect, and that there is a ceiling to this concentration-response relationship.
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Nippon Sanka Fujinka Gakkai Zasshi · Dec 1982
[Studies on neurobehavioral response (Scanlon test) in newborns after epidural anesthesia with various anesthetic agents for cesarean section].
In order to examine the influence of larger doses of anesthetic drugs on newborns, 146 infants delivered by cesarean section with epidural anesthesia employing various anesthetic agents were assessed by Apgar score, blood gas analysis, drug concentration as well as Scanlon's examination. The following results were obtained: 1. ⋯ The groups whose mothers had received epidural block with either lidocaine or mepivacaine for cesarean section showed significantly lower scores in Scanlon test compared with the groups with bupivacaine or chloroprocaine and spinal anesthesia group. From these findings, it may be concluded that bupivacaine or chloroprocaine does offer some advantages over (three local anesthetic agents) lidocaine, mepivacaine or tetracaine to the obstetric patients who need cesarean section for delivery.