European journal of anaesthesiology
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The kneeling prone position is often used for low back surgery in order to decrease intraoperative bleeding and increase the surgical exposure of the vertebral canal. The aim of this study was to assess effects of the kneeling prone position on respiratory gas exchange focusing on oxygen consumption and early changes in oxygenation. ⋯ The present study demonstrates that the kneeling prone position improves oxygenation and that the mechanisms involved are fast in onset. Furthermore, the prone position does not change oxygen consumption although alveolar ventilation is significantly reduced. The changes in alveolar ventilation could possibly be the result of circulatory changes caused by the prone position, but further studies are needed to clarify that hypothesis.
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Randomized Controlled Trial Comparative Study Clinical Trial
A comparison of the effects of ranitidine and omeprazole on volume and pH of gastric contents in elective surgical patients.
In cases of aspiration of gastric contents the risk of pneumonitis is dependent on the pH and volume of the gastric contents. Omeprazole and rantidine each decrease gastric volume and increase gastric pH. We evaluated the efficacy of preoperative administration of omeprazole (60 mg) or ranitidine (150 mg) in the prophylaxis of aspiration pneumonitis. ⋯ Preoperative oral administration of omeprazole (60 mg) or ranitidine (150 mg) reduced residual gastric content volume and increased pH > 2.5, possibly reducing the effects of pulmonary aspiration of gastric contents.
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Randomized Controlled Trial Multicenter Study Comparative Study Clinical Trial
Conventional stepwise vs. vital capacity rapid inhalation induction at two concentrations of sevoflurane.
A multicentre study was conducted to compare three methods of inhalation induction with sevoflurane in adult premedicated patients. ⋯ Inhalation induction of anaesthesia with sevoflurane with the three techniques tested is safe, reliable and well accepted by the patients. The vital capacity rapid inhalation group primed with sevoflurane 8% was the fastest method with no relevant side-effects.
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As atelectasis occurs in most patients during general anaesthesia and may be one of the major causes for the development of hypoxaemia and nosocomial pneumonia, its prevention may be considered as an important objective in perioperative management. The major causative mechanisms are the loss of respiratory muscle tone, compression and gas absorption. ⋯ In this review we describe the pathogenesis of atelectasis in the perioperative period and discuss in the light of recent published investigations the suitability of the vital capacity manoeuvre as a tool during general anaesthesia. Reviewing the current literature, a vital capacity manoeuvre during general anaesthesia may only be useful under specific circumstances when mechanical ventilation with a high inspiratory fraction of oxygen is required or during cardiac surgery at the end of cardiopulmonary bypass to reduce the amount of atelectasis and to maintain adequate gas exchange.
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To investigate the clinical application of a mathematical model of pulmonary gas exchange, which ascribes hypoxaemia to shunt and ventilation/perfusion mismatch. Ventilation/perfusion mismatch is quantified by deltaPO2, which is the drop in oxygen pressure from alveoli to lung capillaries. Shunt and deltaPO2 were used to describe changes in oxygenation after coronary artery bypass grafting. ⋯ Ventilation/perfusion mismatch (deltaPO2), rather than shunt, explains the changes in postoperative oxygenation. The model of pulmonary gas exchange may serve as a useful and potentially non-invasive clinical tool for monitoring patients at risk of postoperative hypoxaemia.