Anesthesiology
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Randomized Controlled Trial
ED(50) and ED(95) of intrathecal bupivacaine in morbidly obese patients undergoing cesarean delivery.
It has been suggested that morbidly obese parturients may require less local anesthetic for spinal anesthesia. The aim of this study was to determine the effective dose (ED(50)/ED(95)) of intrathecal bupivacaine for cesarean delivery in morbidly obese patients. ⋯ Obese and nonobese patients undergoing cesarean delivery do not appear to respond differently to modest doses of intrathecal bupivacaine. This dose-response study suggests that doses of intrathecal bupivacaine less than 10 mg may not adequately ensure successful intraoperative anesthesia. Even when the initial block obtained with a low dose is satisfactory, it will not guarantee adequate anesthesia throughout surgery.
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Preclinical evidence suggests that commonly used anesthetic agents induce long-lasting neurobehavioral changes when administered early in life, but there has been virtually no attention to the neurodevelopmental consequences for the fetus of maternal anesthesia. This study tested the hypothesis that fetal rats exposed to isoflurane during maternal anesthesia on gestational day 14, which corresponds to the second trimester in humans, would be behaviorally abnormal as adults. ⋯ Rats exposed to isoflurane in utero at a time that corresponds to the second trimester in humans have impaired spatial memory acquisition and reduced anxiety, compared with controls. This suggests the fetal brain may be adversely affected by maternal anesthesia, and raises the possibility that vulnerability to deleterious neurodevelopmental effects of isoflurane begins much earlier in life than previously recognized.
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Opioids are powerful analgesics, but are also common drugs of abuse. Few studies have examined how neuropathic pain alters the pharmacology of opioids in modulating limbic pathways that underlie abuse liability. ⋯ Nerve injury suppressed potentiation of electrical stimulation of the ventral tegmental area by opioids, suggesting that the positive reinforcing effects are diminished by chronic pain. Given concerns regarding prescription opioid abuse, developing strategies that assess both analgesia and abuse liability within the context of chronic pain may aid in determining which opioids are most suitable for treating chronic pain when abuse is a concern.