British journal of anaesthesia
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The compound electromyographic response of the thenar musculature was elicited by supramaximal stimulation of the ulnar nerve in 12 awake healthy volunteers. The half-refractory period of the neuromuscular transmission was determined. Twin stimuli separated by the half-refractory interval were repeated as a unit at 2 Hz and at 50 Hz. ⋯ A secondary fade occurred occasionally. These changes were more remarkable in the train of half-refractory responses. We conclude that nerve stimulation facilitates neuromuscular transmission and deduce that the characteristic fade observed with a curariform block, rather than being an uncovered physiological phenomenon, is caused by tubocurarine and related drugs.
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Plasma concentrations of local anaesthetic agents have been measured after 40 interscalene brachial plexus blocks in 39 patients, using lignocaine, prilocaine, bupivacaine and etidocaine. Lignocaine produced greater concentrations than prilocaine, and bupivacaine greater concentrations than etidocaine. The addition of adrenaline resulted in much lower concentrations in the case of all four agents.
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Case Reports
Absence of "recurarization" in patients with demonstrated prolonged neuromuscular block.
The possibility of "recurarization" after antagonism of the competitive neuromuscular block with anticholinesterases was studied. Observations were made on the time-course of the block in five patients at risk from recurarization because of multiple organ failure and who demonstrated unusually prolonged blockade. In none of these patients did the block recur. We conclude that, provided spontaneous recovery of neuromuscular transmission has made progress before the antagonism, and that the patient does not deteriorate or become exhausted afterwards, recurarization is unlikely.
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The effectiveness and safety of etidocaine during extradural anaesthesia for Caesarean section were evaluated in 81 patients. Adequate sensory analgesia occurred in 78 patients and muscle relaxation was excellent in all patients. ⋯ Neurobehavioural patterns of the newborn were not affected noticeably. Etidocaine, in appropriate dose and concentration, appears to be an excellent local anaesthetic agent for Caesarean section under extradural anaesthesia.
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Clinical Trial Controlled Clinical Trial
Anaesthesia for Caesarean section. Analysis of blood concentrations of halothane using 0.2% or 0.65% halothane with 50% nitrous oxide in oxygen.
In 15 patients anaesthesia for elective Caesarean section was maintained with 50% nitrous oxide in oxygen and a 0.65% halothane supplement. In a further 15 mothers a 0.2% halothane supplement was used. In those mothers receiving 0.65% halothane intermittent measurements were made of maternal arterial halothane concentrations during the uptake and the excretion of the agent. ⋯ The use of 0.2% and 0.65% halothane supplements prevented awareness in all the mothers. However, dreaming occurred in two patients given a 0.2% halothane supplement. Studies are required to establish the minimum halothane supplement required to prevent awareness in a larger series of patients.