Anesthesiology
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Comparative Study
Spinal adrenergic and cholinergic receptor interactions activated by clonidine in postincisional pain.
Previous pharmacologic and molecular studies suggest that the alpha(2)-adrenoceptor subtype A is the target for spinally administered alpha(2)-adrenergic agonists, i.e., clonidine, for pain relief. However, intrathecally administered alpha(2) C antisense oligodeoxynucleotide was recently reported to decrease antinociception induced by clonidine in the rat, suggesting non-A sites may be important as well. The current study sought to determine the subtype of alpha(2) adrenoceptors activated by clonidine in a rodent model for human postoperative pain, and to examine its interaction with spinal cholinergic receptors. ⋯ Both alpha(2) A and alpha(2) non-A adrenoceptors, as well as spinal cholinergic activation, are important to the antihypersensitivity effect of clonidine after surgery. ST91 is more efficacious in this model than clonidine and relies entirely on alpha(2) non-A adrenoceptors.
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To prevent neurologic damage, monitoring cerebral function by somatosensory evoked potentials is used in selected settings. Excision of intraocular melanoma provides a unique opportunity to assess independently during anesthesia the effects on median nerve somatosensory evoked potentials (MN-SSEPs) and cerebral oxygen extraction of sodium nitroprusside-evoked arterial hypotension with and without hypothermia. ⋯ Thus, hypothermia to 32 degrees C does not alter MN-SSEP amplitude and global cerebral oxygen extraction during marked sodium nitroprusside-induced arterial hypotension with a mean arterial pressure of 40 mmHg but prolongs MN-SSEP latencies during propofol-remifentanil anesthesia in individuals without cerebrovascular disease.
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Outpatient knee surgery has come to involve increasingly complex procedures. The authors present observational data from a nerve block algorithm designed for the care of outpatients undergoing knee surgery. The aim of this report is to demonstrate differences in pain and unplanned hospital admission associated with surgical complexity and nerve blocks used. ⋯ For complex knee surgery, the use of FSB was associated with less pain; the use of FNB or FSB (vs. no block) was associated with fewer hospital admissions.
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The roles of descending facilitatory pathway from the rostral medial medulla (RMM) in development of persistent spontaneous nociception and hyperalgesia were evaluated in the bee venom (BV) test and the formalin test. ⋯ The present results provide a new line of behavioral evidence that tonic activation of descending facilitatory pathway contributes to the establishment of 1) the BV and formalin-induced persistent spontaneous nociception; and 2) the BV-induced referred mirror heat hyperalgesia and the central sensitization, but not the primary heat and mechanical hyperalgesia.