British journal of anaesthesia
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The value of respiratory variables as weaning predictors in the intensive care unit (ICU) is controversial. We evaluated the ability of tidal volume (Vt(exp)), respiratory rate (f), minute volume (MV(exp)), rapid shallow breathing index (f/Vt), inspired-expired oxygen concentration difference [(I-E)O(2)], and end-tidal carbon dioxide concentration (Pe'(co(2))) at the end of a weaning trial to predict early weaning outcomes. ⋯ In unselected ICU patients, respiratory variables predict early weaning from mechanical ventilation poorly.
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The loss of cholinergic neurones in the basal forebrain has been shown to correlate to the extent of cognitive dysfunction during ageing in humans and to the hypnotic potency of propofol in animal models. We examined how the preoperative cognitive status, as assessed by mini-mental state examination (MMSE), may interact with propofol consumption during anaesthesia in the elderly. ⋯ Propofol requirement to maintain hypnosis during general anaesthesia appears to decrease with deterioration in the cognitive status in the elderly. We suggest that a cognitive dysfunction linked to a cerebral cholinergic dysfunction may influence the brain sensitivity for propofol in aged patients.
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Studies of preoperative cardiopulmonary exercise testing (CPET) have shown that a reduced oxygen uptake at anaerobic threshold (AT) and elevated ventilatory equivalent for carbon dioxide (VE/VCO(2)) were associated with reduced short- and medium-term survival after major surgery. The aim of this study was to determine the relative values of these, and also clinical risk factors, in identifying patients at risk of death after major intra-abdominal, non-vascular surgery. ⋯ The routine measurement of AT and VE/VCO(2) using CPET for patients undergoing high-risk surgery can accurately identify the majority of high-risk patients, while the use of clinical risk factors alone will only identify a relatively small proportion of at-risk patients.