British journal of anaesthesia
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The effect on intervillous blood flow of lumbar extradural analgesia for Caesarean section was studied in nine healthy women using xenon-133. Extradural anaesthesia was performed with lignocaine 1 1/2% 16--20 ml with adrenaline 5 microgram ml-1. Impairment of placental blood flow during the block was observed in seven patients, but the mean decrease (13% from the control value) was not statistically significant. The most notable decrease in intervillous blood flow occurred in two patients with simulateous arterial hypotension.
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The plasma concentrations of pancuronium were monitored during i.v. infusions of the relaxant in dogs. Pancuronium was administered at rates which maintained the degree of neuromuscular blockade at three predetermined levels. The concentrations of the drug in the blood were consistent for any one animal but showed considerable overlap for the three levels of paralysis between animals. ⋯ The concentrations at 80% of control were 0.094 microgram ml-1 and 0.083 microgram ml-1 respectively. The agreement between these results suggests a relationship between the plasma concentration of the relaxant and its effect during the termination of the action after a large bolus injection of the drug. As this occurs chiefly during the postdistribution equilibrium, the relatively slow decrease in plasma concentration would appear to become the rate-limiting factor in recovery from paralysis.
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The effects of bilateral adrenalectomy, together with the i.v. administration of bretylium tosylate 20 mg kg-1 on halothane-induced malignant hyperthermia (MH), were investigated in six Pietrain pigs. All six animals survived the halothane challenge, and failed to show any signs of increased muscle metabolism. Bilateral adrenalectomy alone prevented halothane-induced MH in three out of four Pietrain pigs, whereas the i.v. administration of bretylium alone protected only one pig out of an additional four animals studied. The results show that complete adrenergic blockade inhibits the susceptibility of Pietrain skeletal muscle to halothane and that the adrenal medulla makes an important contribution to this response.
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Randomized Controlled Trial Comparative Study Clinical Trial
A comparison of the effect of three anaesthetic techniques on postoperative arterial oxygenation in the elderly.
Ninety patients (age range 49--99 yr) with a fracture of the neck of the femur were anaesthetized by a technique using halothane in oxygen in a closed circuit, halothane and 66% nitrous oxide in oxygen in a Magill circuit or artificial ventilation with 66% nitrous oxide in oxygen ("IPPV group"). In all three groups, there was a small decrease in PaO2 from an overall mean of 9.07 kPa before operation to 8.13 kPa at 60 min after anaesthesia. There was no significant difference between the groups in respect of the decrease; it was concluded that closed-circuit halothane in oxygen anaesthesia for this type of surgery was not accompanied by a significant degree of absorption collapse.