British journal of anaesthesia
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Atracurium has been evaluated in anaesthetized patients using the single twitch and tetanic responses of the adductor pollicis muscles. I.v. doses of 0.3-0.9 mg kg-1 produced complete neuromuscular block. In the dose range used mean arterial pressure was only decreased by about 20% of control for a few minutes after 0.9 mg kg-1 which was three times the standard dose. ⋯ Intubation of the trachea could be accomplished when blockade of the tetanic response was complete and at a time when the single twitch was only slightly depressed. It was concluded that the tetanic response provided a more accurate assessment of the time-course of neuromuscular blockade than the single twitch. Infusion studies demonstrated that recovery from full neuromuscular blockade after a 30- or 60-min infusion was as rapid as that after bolus doses of atracurium 0.3-0.9 mg kg-1 and this could be regarded as further evidence of the lack of cumulative effects.
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Comparative Study Clinical Trial Controlled Clinical Trial
Muscular relaxation with atracurium, vecuronium and duador under balanced anaesthesia.
The neuromuscular effects of three new nondepolarizing neuromuscular blocking drugs, atracurium, vecuronium and Duador, were investigated in surgical patients under balanced anaesthesia. (The numbers of patients in each study are given in the tables.) There were no significant differences in the neuromuscular effects of the three agents. None showed any cumulation after repeated administration of maintenance doses. Muscular relaxation for upper abdominal surgery was adequate as long as the isometric twitch tension (P) was no more than 25% of control. ⋯ The initial dose of Duador caused a 16.7% increase in heart rate. The findings indicate that the three new muscle relaxants merit further clinical trial. In our opinion, until the results of such studies become available, atracurium should not be used in patients with a history of allergic diathesis and Duador in those in whom increased heart rate may be harmful.
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Comparative Study
Evaluation of cumulative properties of three new nondepolarizing neuromuscular blocking drugs BW A444U, atracurium and vecuronium.
Comparative patterns of recovery during successive doses of three new, relatively non-cumulative, intermediate-duration non-depolarizing neuromuscular blocking drugs, BW A444U, atracurium (BW33A) and vecuronium (Org NC 45), were studied in 94 surgical patients during thiopentone in nitrous oxide and oxygen with narcotic anaesthesia. The train-of-four (TOF) pattern of nerve stimulation was used. The spontaneous 5-25% recovery time of the first twitch of TOF showed a statistically significant difference between the initial dose and the fifth incremental dose in the cases of atracurium and vecuronium, but not in the case of BW A444U. ⋯ The difference was significant only when the final dose of vecuronium was compared with the initial dose (TOF ratio 79.3 +/- 2.3% v. 64.3 +/- 4.4%; P less than 0.005). Analysis of variance indicates that the TOF ratio at 95% recovery of the first twitch of TOF after the final dose of vecuronium (64.3%) is significantly smaller (P less than 0.001) than that of either BW A444U (78%) or atracurium (84%), indicating that vecuronium appears to show more residual fade and greater cumulative effect after incremental doses than BW A444U or atracurium. The data suggest that the cumulative properties of the new drugs may be ranked as follows: atracurium less than BW A444U less than vecuronium.
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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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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).