Canadian Anaesthetists' Society journal
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Many authors have reported middle ear pressure variations during inhalation of high concentrations of nitrous oxide. An on-going study on subjects anaesthetized with nitrous oxide and oxygen supplemented with halogens or narcotics and excluding operations on the ear enables us to register three typical curves of middle ear pressure according to the patency of the Eustachian tube. ⋯ The presence of a tympanic "neomembrane" due to an old perforation associated with important obstruction of the Eustachian tube could lead to a tympanic perforation that may be unnoticed by the anaesthetist if it is not specifically investigated. In our series, we report one case of tympanic perforation and one case of haemotympanum as examples of such consequences.
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Comparative Study Clinical Trial Controlled Clinical Trial
Comparative trial of the effect of ranitidine and cimetidine on gastric secretion in fasting patients at induction of anaesthesia.
A comparative trial of the H2-receptor antagonists, cimetidine and ranitidine, on gastric pH and volume, was conducted in 168 healthy patients coming to elective surgery. The drugs were administered in random fashion either intravenously (ranitidine 50 mg or 100 mg, cimetidine 300 mg or placebo) or orally (ranitidine 150 mg, cimetidine 300 mg or placebo). The patients received the drugs or placebo 45 minutes to five hours before operation. ⋯ We conclude that the intravenous use of either ranitidine or cimetidine is an acceptable method to decrease the acidity of gastric contents before induction of anaesthesia. Orally, ranitidine appears to be a better choice than cimetidine in the doses studied. Both ranitidine and cimetidine need to be given at least 45 minutes before induction of anaesthesia to be effective; therefore the use of these agents to decrease the risk of acid pulmonary aspiration syndrome by no means obviates the need for proper anaesthesia technique during induction of anaesthesia.