British journal of anaesthesia
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Comparative Study
Neuromuscular and cardiovascular effects of atracurium during nitrous oxide-fentanyl and nitrous oxide-isoflurane anaesthesia.
The neuromuscular and cardiovascular effects of atracurium were compared during nitrous oxide-isoflurane and nitrous oxide-fentanyl anaesthesia in healthy surgical patients. The dose-response curve was shifted significantly to the left during nitrous oxide-isoflurane anaesthesia (ED50 0.068 mg kg-1) as compared with nitrous oxide-fentanyl anaesthesia (ED50 0.083 mg kg-1). For equipotent doses, the time course of neuromuscular effects (onset and duration) was not appreciably different between the nitrous oxide-isoflurane group and the nitrous oxide-fentanyl group. ⋯ The onset time (time from injection to peak effect) for subparalytic doses of atracurium was approximately 6.5 min and is comparable to the onset time for equipotent doses of pancuronium and vecuronium. The duration of neuromuscular effects of atracurium (time from injection to 95% recovery) was approximately 20 min for subparalytic doses and is the same as that of vecuronium and one-third to one-half that of pancuronium. It is concluded that the peak effect of atracurium is enhanced more by nitrous oxide-isoflurane than by nitrous oxide-fentanyl anaesthesia, but for equipotent doses the time-course is the same.
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Comparative Study
Comparative study of atracurium, vecuronium (Org NC 45) and pancuronium.
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Conditions for endotracheal intubation provided by different dose regimens of atracurium 0.4 mg kg-1 and 0.5 mg kg-1 were studied and compared with each other and with suxamethonium 1.0 mg kg-1. Intubation was attempted at 2.5, 2 min and 1.5 min following a bolus dose of atracurium, and 1 min following suxamethonium. ⋯ Atracurium, when administered 5 min following recovery from a suxamethonium-induced block, had a significantly faster onset of neuromuscular blockade (P less than 0.01) than the onset observed following atracurium alone. Administration of atracurium 0.42 mg kg-1 3 min after an initial dose of 0.08 mg kg-1 of the drug produced a significantly more rapid onset of block when compared with a bolus dose of 0.5 mg kg-1 (P less than 0.02).
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Comparative Study
Ventilatory effects during and after continuous infusion of fentanyl or alfentanil.
The opioid drugs fentanyl and alfentanil were infused at a constant rate as supplements to nitrous oxide in oxygen anaesthesia throughout the period of surgery. These infusions were continued into the period after operation for 1 h after the discontinuation of anaesthesia. Continuous infusion of alfentanil 20 micrograms kg-1 h-1 and fentanyl 3 micrograms kg-1 h-1 resulted in depression of the carbon dioxide response curve with a lesser effect on frequency and minute ventilation. One hour after discontinuing the infusions the degree of ventilatory depression was only marginally less with fentanyl, but considerably less with alfentanil, reflecting the shorter terminal half-life of that drug.
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The effects of halothane and of prior administration of suxamethonium on atracurium neuromuscular blockade have been investigated. Halothane potentiated the intensity of block produced by atracurium 0.1 or 0.15 mg kg-1. Duration of block was prolonged (27%) by halothane with a small dose of atracurium (0.15 mg kg-1) and was also prolonged (29%) with larger doses of atracurium (0.4 mg kg-1). Prior suxamethonium 1 mg kg-1 increased the intensity of block after atracurium 0.15 mg kg-1 from 52% (control) to 84%, but caused minimal change in duration of atracurium blockade.