Canadian Anaesthetists' Society journal
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A new method for the detection and recording of the oculocardiac reflex (OCR) is described and applied to 49 healthy infants and children (six months to nine years old) undergoing strabismus surgery under halothane anaesthesia with spontaneous ventilation. Eighty-one extraocular muscles were studied. Square wave stimuli (abrupt and sustained tractions) were definitely more reflexogenic than slow slope stimuli (very gradual, progressive and gentle tractions). ⋯ Controlled ventilation is recommended. The routine use of intravenous anticholinergic drugs is briefly discussed. Prevention of the OCR, and prophylaxis of cardiac arrhythmias during strabismus surgery, now seem to be placed on a more rational basis.
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Clinical Trial Controlled Clinical Trial
Neuromuscular blockade in infants following intramuscular succinylcholine in two or five per cent concentration.
This study determined the characteristics of the neuromuscular block which followed intramuscular succinylcholine 4 mg . kg-1 in 20 infants during halothane anaesthesia. The infants were divided into two groups of ten; the first received succinylcholine in two percent solution and the second in five per cent solution. The mean maximum depression of the first twitch of the train-of-four (T1) was 89.7 +/- 5.0 per cent in 4.0 +/- 0.6 min, and the mean full recovery of T1 occurred in 15.6 +/- 0.9 min after injection. ⋯ Depolarizing block, with equal depression of all twitches of the train-of-four was observed during the onset of neuromuscular blockade. During recovery, phase II block, as determined by a train-of-four ratio (T4/T1) of 0.5 or less, occurred frequently at T1 recovery of 25-50 per cent, but was not associated with prolonged paralysis. It is concluded that the onset time of 4 min for intramuscular succinylcholine 4 mg . kg-1 may be too long for emergency use in infants, and no improvement is obtained by increasing the concentration of injected succinylcholine from two to five per cent.