British journal of anaesthesia
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Meta Analysis
Meta-analysis of the efficacy of extradural clonidine to relieve postoperative pain: an impossible task.
Clonidine, an alpha2 adrenoceptor agonist, has anti-hypertensive and anti-nociceptive effects. It is commonly used in association with local anaesthetics and opioids to enhance the quality and duration of extradural analgesia in the postoperative period, and to decrease the incidence of side effects. As a sole analgesic, it has seldom been used to relieve postoperative pain. ⋯ The data from these studies were difficult to interpret because of the tremendous variation in variables, especially dose of clonidine, level of extradural injection, time of administration, type of anaesthesia, type of surgery, and reference and rescue drugs. The simultaneous extradural use of local anaesthetics and opioids further hindered data interpretation, and precluded any meta-analysis. Proposals for a standard study design are made to help comparison between studies involving extradural clonidine and postoperative pain.
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Randomized Controlled Trial Clinical Trial
Pharmacological vasodilatation improves efficiency of rewarming from hypothermic cardiopulmonary bypass.
An afterdrop in core temperature after hypothermic cardiopulmonary bypass (CPB) is related to inadequate peripheral rewarming. We proposed that pharmacological vasodilatation during rewarming on bypass would improve peripheral rewarming and reduce the degree of afterdrop. Fifty-nine of 120 patients were randomized to receive a sodium nitroprusside (SNP) infusion during the rewarming stage of hypothermic CPB. ⋯ Patients receiving SNP had a warmer mean peripheral temperature (MPT) (32.9 degrees C vs 32.4 degrees C; P = 0.05) on termination of CPB. Postoperative core temperature fell less in the SNP group (35.6 degrees C vs 35.2 degrees C; P = 0.01) as did MPT (31.8 degrees C vs 31.2 degrees C; P = 0.004). SNP-induced vasodilatation during rewarming from hypothermic CPB improves peripheral rewarming, reduces the degree of postoperative core and peripheral hypothermia and reduces time to extubation.
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We describe a 73-yr-old woman anaesthetized for a laminectomy. She suffered from hepatic failure with mild encephalopathy complicated by several exacerbations associated with sedative and opioid therapy. ⋯ We used remifentanil to provide intraoperative and postoperative analgesia, because it has a short duration of action and does not require hepatic metabolism. We closely monitored the respiratory and the neurological status throughout the administration and conclude that remifentanil can provide perioperative analgesia in patients at risk of developing hepatic encephalopathy.
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The influence of aging on the pharmacodynamics of anaesthetic agents in the central nervous system remains poorly understood. As alpha-aminobutyric acid (GABA)-mediated neurotransmission appears to be an important target for anaesthetics in the brain, we hypothesized that aging could alter the sensitivity of the GABA carrier to anaesthetics. We have examined the effects of etomidate and propofol on the uptake of [3H]-GABA (5 min, 37 degrees C) into striatal synaptosomes of rats aged 2, 18 and 24 months. ⋯ Aging increased IC50 values for these anaesthetics. Nipecotic acid was unaffected. These data suggest that aging selectively alters the action of etomidate and propofol in the mammalian CNS.