British journal of anaesthesia
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The effects of some anaesthetics and other agents used in anaesthetic practice on the neuromuscular blocking activity of cumulative doses of Org NC 45 have been studied in cats anaesthetized with chloralose. As expected from studies with other neuromuscular blocking drugs, both inhalation and i.v. anaesthetics reduced the doses of Org NC 45 required for neuromuscular blockade. An apparently specific potentiating interaction between Org NC 45 and metronidazole was observed.
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The pharmacokinetics and analgesic effects of i.m. and oral ketamine in a dose of 0.5 mg kg-1 were determined in six healthy volunteers. Analgesia was measured by the submaximal effort tourniquet test. ⋯ The plasma ketamine concentration associated with analgesia was 150 ng ml-1 following the i.m. dose, but only 40 ng ml-1 after the oral dose. Oral administration was, however, associated with much greater concentrations of the metabolite norketamine, which may have contributed to the analgesic effect.
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Cyanide antidotes were given to dogs before an infusion of sodium nitroprusside 1.5 mg kg-1 for 1 h. Dogs given thiosulphate 75 mg kg-1 had significantly lower plasma and red cell cyanide concentrations while plasma thiocyanate concentrations were significantly increased in comparison with control. These changes were associated with only minimal disturbance of tissue oxygenation. ⋯ There was no evidence of a synergistic action between thiosulphate and hydroxocobalamin. The vascular response to nitroprusside was unchanged in the thiosulphate-treated dogs, but was significantly greater in those given hydroxocobalamin. The implications for prophylaxis and treatment of cyanide poisoning following nitroprusside overdose are discussed.
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Comparative Study Clinical Trial Controlled Clinical Trial
Postoperative spinal analgesia with morphine.
Patients with pain after operation received morphine hydrochloride intrathecally in doses of 0.02 mg kg-1 (n = 30) and 0.2 mg kg-1 (n = 30). The high-dose group showed slightly longer-lasting and more potent analgesia than the low-dose group. ⋯ Two patients of the high-dose group showed evidence of respiratory depression which appeared after a late change in posture (7 and 11 h). We conclude that postoperative analgesia with intrathecal morphine 0.02 mg kg-1 must be followed by a prolonged head-up posture and be performed in hospital units where the treatment of respiratory depression is competent.
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A forearm tourniquet for i.v. regional analgesia of the hand, using doses of bupivacaine smaller than in the conventional (upper arm) method, produced successful analgesia in 98 of 102 patients. In 63 patients bupivacaine 50 mg or less was adequate, while in 33 the dosage was between 60 and 75 mg. No toxic effect was noted. This technique permits surgery of the hand, wrist and distal forearm.