Canadian Anaesthetists' Society journal
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The effects of pretreatment with both sub-paralyzing and paralyzing doses of pancuronium and d-tubocurarine, on the onset and duration of succinylcholine-induced neuromuscular blockade were evaluated and compared in 225 patients. D-tubocurarine antagonized both onset and duration of succinylcholine block, while pancuronium produced a dual effect, antagonizing the onset and potentiating the duration of succinylcholine block. ⋯ Pancuronium (0.02 mg/kg, 0.04 mg/kg and 0.08 mg/kg) also antagonized the onset of succinylcholine paralysis with increases of 32 to 114%, but potentiated its duration from 30 to 103% compared with succinylcholine alone in the same patients. Although pancuronium markedly inhibited serum cholinesterase in vitro (I50=5 X 10(-7) mol) there was only a 10% inhibition of cholinesterase in vivo after pancuronium 0.08 mg/kg.
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This study assesses the effects of agents commonly used in anaesthesia on enflurane-induced seizure threshold and on established seizure activity, during steady state enflurane anaesthesia. EEG seizure activity was monitored in cats from chronic cortical and subcortical recording sites. Diazepam, thiopentone, methohexitone and ketamine all enhanced established EEG seizure challenge. ⋯ The effects of these intravenous agents on established enflurane seizure patterns exceeded in duration the expected EEG effect of the agent when used alone. The limited number of experiments, however, precluded statistical verification of our findings. The similarities between centrencephalic minor motor seizures and enflurane seizure pattern in terms of EEG and convulsive expression, including drug response, are noted.
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Clinical Trial
Clinical trial of etomidate. Preliminary observations on a new non-barbiturate induction agent.
This is a preliminary report of our clinical experience with etomidate, a new intravenous non-barbiturate anaesthetic agent. Thirty-two patients undergoing minor surgical procedures were anaesthetized, induction being with etomidate 0.3 mg/kg body weight. Induction was fast and smooth. ⋯ Following etomidate injection, 37.5 per cent of patients developed myoclonic movements which were usually mild and self-limiting. We were impressed by the relative stability of the cardiovascular and respiratory systems. Etomidate looks promising and further work is in progress on other aspects of this drug.
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Studies carried out in the laboratory have shown that an S-shaped cannula for trans-laryngeal jet ventilation provides a distinct advantage over conventional straight ones. Tidal volumes are larger and the cannula is more stable in position. The tendency of perforate the posterior wall of the trachea during introduction is also minimal. ⋯ It can be put in position before induction of anaesthesia to enable preoxygenation and assist ventilation and can be left in place at the end of the operation until the patient is breathing adequately. If necessary, a tracheostomy can be done with the cannula in situ. It is not proposed that this should be the standard mode of anaesthesia or ventilation for patients undergoing operations on the larynx, but in stituations where other methods are not adequate and when significant upper airway obstruction is present, this is an excellent alternative.