British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Intranasal administration of nitroglycerine attenuates the pressor response to laryngoscopy and intubation of the trachea.
The intranasal administration of nitroglycerine (NTG) was undertaken in 35 adult female patients 1 min before the induction of anaesthesia. A control group consisting of 32 patients did not receive NTG. Systolic arterial pressure (SAP) and heart rate (HR) were recorded before the induction of anaesthesia and at 0, 3, and 5 min after tracheal intubation. ⋯ SAP did increase significantly in the control group. HR was increased in both groups immediately after intubation (P less than 0.001 and P less than 0.001 respectively). NTG administered intranasally is a safe, simple and effective method to attenuate the hypertensive response to laryngoscopy and tracheal intubation.
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The antagonistic action of a bolus dose of edrophonium 0.75 mg kg-1 on the neuromuscular blockade induced by atracurium was studied in 10 patients anaesthetized with nitrous oxide and narcotic supplements. The reversal agent was administered when the twitch height had recovered spontaneously to approximately 20% of control. ⋯ Clinically adequate reversal (train-of-four ratio of 75% or better) was achieved 6.6 +/- 1.5 min following injection of the edrophonium and there was no evidence of subsequent muscle weakness. The possible advantages of the clinical use of edrophonium in producing a rapid reversal of atracurium blockade are discussed.
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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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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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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.