British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Acute i.v. Methadone Kinetics in Man: relationship to chronic studies.
Twenty-six patients were given methadone 10 mg i.v. to obtain acute human kinetics. Plasma methadone concentrations from separate 3- and 6-h studies were measured by radioimmunoassay. Kinetic parameters derived from triexponential NONLIN analysis showed that T1/2 alpha and T1/2 beta were 2 and 30 min respectively; no reliable estimate for T1/2 gamma could be obtained. ⋯ The difficulties in determining accurate terminal half-life and clearance values from short duration studies are discussed; these difficulties are accentuated by the long terminal half-life of methadone. Appropriate estimates of clearance may be derived from an acute short duration study provided that the average of triexponential fits to individual patients data is used, even when data extend from only 3h. As might be anticipated, no analysis produced appropriate terminal half-life values for this drug.
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Case Reports
Use of metyrosine in the anaesthetic management of patients with catecholamine-secreting tumours. A case report.
Metyrosine 1.5 g daily for days decreased 24-h urine metanephrine concentration by about 60% in a patient with multiple catecholamine-secreting paragangliomas. Despite the considerable inhibition of catecholamine synthesis, this patient exhibited stress-induced sympathetic overactivity, indicated by increases in arterial pressure and serum catecholamine and urine metanephrine concentrations. ⋯ In this way, optimal inhibitory effect on catecholamine synthesis can be obtained and maintained for a sufficient time to allow catecholamine stores to become as close to normal as possible. Attainment of the optimal therapeutic effect is not clearly defined, but would seem to be best gauged by a combination of clinical tests of sympathetic responses and of suppression of urinary excretion of metanephrines or VMA.
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Randomized Controlled Trial Comparative Study Clinical Trial
Postoperative analgesia after circumcision in children.
The analgesic effects of systemically administered diamorphine, caudal analgesia with 0.5% bupivacaine plain and caudal analgesia with 0.5% bupivacaine plain to which morphine sulphate had been added were studied in boys undergoing circumcision. Postoperative analgesia was assessed using a linear analogue scale. The time interval between operation and subsequent analgesic administration and the number of analgesic doses in 24 h were compared. ⋯ The only detectable difference between the groups was a more rapid, but transient, recovery in the group receiving plain bupivacaine only. The frequency of vomiting was high in all groups. Caudal analgesia, with or without the addition of morphine, did not confer any advantage over injected diamorphine, and did not justify the extra time, risk and expense required to carry it out.
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The use of atracurium in 25 patients undergoing general surgical procedures is described, neuromuscular function being monitored by the "train-of-four" stimuli. An initial dose of atracurium 0.5 mg kg-1 proved to be clinically acceptable, giving good conditions for endotracheal intubation and adequate muscle relaxation for about 40 min. Comparison of the results with those from 15 patients given suxamethonium 50 mg showed that atracurium in this dosage took longer to produce complete ablation of the twitch responses but that it lasted longer (about 40 min). ⋯ Reversal of the neuromuscular block with neostigmine was prompt and adequate. Using simple clinical means no evidence of an important change in heart rate or arterial pressure was found. There were no adverse reactions to the drug.