Anesthesiology
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Highly potent toxins such as tetrodotoxin that block sodium channels with great specificity have been studied for many years and can provide prolonged blockade when coadministered with vasoconstrictors or conventional local anesthetics. Their utility has been constrained, however, by systemic toxicity. The authors examined the efficacy of tetrodotoxin with and without epinephrine or bupivacaine for producing prolonged-duration sciatic nerve blockade in the rat, and they assessed the degree of concomitant toxicity. ⋯ Combinations of epinephrine or bupivacaine with tetrodotoxin or with other high-potency toxins active on sodium channels should be examined for the potential to provide clinically useful, prolonged nerve blockade.
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The incidence of noninfectious systemic inflammatory response syndrome (SIRS) associated with coronary artery bypass surgery and the potential role of several inflammatory parameters as early markers of pulmonary dysfunction induced by cardiopulmonary bypass (CPB) were investigated. ⋯ Procalcitonin seems to be an appropriate parameter indicating the early development of severe noninfectious SIRS and for predicting pulmonary dysfunction secondary to CPB.
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Although inhibition of nitric oxide synthase (NOS) has been reported to be antinociceptive and to reduce the threshold of general anesthesia, the mechanism of action is largely unknown. Specifically, the relation between the minimum alveolar concentration (MAC)-reducing effects of NOS inhibition and cyclic guanosine monophosphate (cGMP) concentrations in the brain has not been defined. To further characterize the effects of NOS inhibition, the authors studied the relation between the MAC of sevoflurane and the cGMP concentration of the brain after acute and chronic treatment with a neuronally selective NOS inhibitor, 7-nitroindazole (7-NI). ⋯ Although an acute selective inhibition of neuronal NOS decreases sevoflurane MAC and cerebellar cGMP concentrations in mice, there was a dissociation between the two parameters during long-term neuronal NOS inhibition. There may be cGMP-independent compensatory mechanisms that mediate nociception when NOS is chronically inhibited.
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Randomized Controlled Trial Clinical Trial
Peripheral analgesic effects of ketamine in acute inflammatory pain.
BACKGROUND. This study examined the analgesic effect of local ketamine infiltration, compared with placebo and systemic ketamine, in a human model of inflammatory pain. ⋯ Ketamine infiltration had brief local analgesic effects, but several measures of pain and hyperalgesia were unaffected. Therefore, a clinically relevant effect of peripheral ketamine in acute pain seems unlikely.
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Randomized Controlled Trial Clinical Trial
Intrathecal sufentanil produces sensory changes without hypotension in male volunteers.
Intrathecally administered sufentanil is frequently associated with hypotension and sensory changes in women undergoing labor. In this study, the authors examined whether intrathecally administered sufentanil has similar effects in pain-free individuals with low concentrations of progesterone (i.e., male volunteers). ⋯ Intrathecally administered sufentanil did not affect blood pressure in male volunteers. The other effects of sufentanil, however, were similar to those observed in women undergoing labor. This suggests that the hypotension occurring in these women after intrathecally administered sufentanil is secondary to relief of pain, rather than to a sympathectomy.