Anaesthesia
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The general relationships between the pressure inside an endotracheal tube cuff, the pressure exerted by that cuff on the tracheal wall and the airway pressure have been re-examined in a model system. In relatively recent literature, the tracheal wall pressure at a given cuff volume has been calculated as the difference between intracuff pressures at that volume when the cuff is inflated inside the trachea and when it is inflated whilst suspended freely in air. This has been used as a general relationship, as an alternative to direct measurement in real and model tracheas. In this study, the directly measured pressure was not generally equal to the pressure as calculated above.
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Seventy-eight cases of cardiac arrest occurring outside intensive care units and emergency rooms were analysed. 44% of patients were initially resuscitated, and 14% were still alive at 28 days. The previously well documented relationships between survival and location of arrest, age of patient and initial dysrhythmia were confirmed. A diurnal variation in the incidence of cardiac arrest has recently been postulated, but was not noted in this survey. However, the proportion of arrest patients who were initially resuscitated did show a significant fluctuation over the 24-hour period as tested by a sinusoidal logistic regression.