Ann Acad Med Singap
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The anaesthesia specialty has focused on the safety of the patient and examination of untoward outcomes. Serious injuries are now rare in medically advanced countries. Still, anaesthesia deaths and complications are important because the anaesthetic itself has no intended therapeutic effect. ⋯ Many efforts are believed to have contributed to improvements in the safety of anaesthesia: improved training of anaesthesia clinicians, new pharmaceuticals, new technologies for monitoring (especially pulse oximetry and capnography), standards for monitoring and other aspects of anaesthesia care, safety enhancements in anaesthesia equipment and the implementation of quality assurance and risk management programmes. The creation of the Anesthesia Patient Safety Foundation in the United States and a similar organization in Australia have helped to bring about awareness of safety issues and to support study of patient safety. Ultimately, the motto of the Anesthesia Patient Safety Foundation should be the goal of all anaesthesia professionals: "That no patient shall be harmed by anaesthesia".
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Desflurane is a new fluorinated ether with rapid onset of and recovery from anaesthesia. Recovery characteristics are comparable with or faster than after propofol infusion or isoflurane anaesthesia. The minimum alveolar concentration (MAC) varies with age from 9.4% (infants) to 6% (adults), and is reduced by opioids and sedative premedication. ⋯ Desflurane is a respiratory depressant, and enhances the action of neuromuscular blocking agents. Cerebrovascular autoregulation appears to be preserved, but intracranial pressure may still rise during desflurane anaesthesia. Delivery of vapour is using a new electrically heated vaporizer, the Tec 6, with internal monitoring circuitry and new safety features.
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Weaning from mechanical ventilation may be influenced by factors relating to equipment, techniques and procedures. Criteria to initiate weaning and predictors of weaning outcome are generally unreliable, but mechanical work of breathing, the tidal volume: frequency ratio and the inspiratory pressure: maximal inspiratory pressure ratio may anticipate those likely to fail weaning. ⋯ Blow-by heated humidifiers and ventilators which compensate for the impedances of their inspiratory demand valves impose clinically acceptable spontaneous breathing loads. Close monitoring, adequate respiratory muscle rest, attention to mineral deficiencies, nutrition and pulmonary hygiene are also important parts of the weaning process.
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The effects of anaesthesia and surgery on the chest wall may be responsible for impaired gas exchange and other pulmonary complications during the perioperative period. Current evidence supports the following sequence of events. Anaesthesia changes the shape and motion of the chest wall, either by changing the amount of tonic and phasic activity of the respiratory muscles (anaesthesia with spontaneous breathing) or by eliminating the activity entirely (paralysis with mechanical ventilation). ⋯ For example, it is now apparent that anaesthesia reduces the functional residual capacity not by changing the position of the diaphragm, but rather by affecting the rib cage, and, perhaps, the volume of intrathoracic blood. The effects of anaesthesia and surgery on postoperative chest wall function may be lessened by regional analgesia and the use of laparoscopic surgical techniques. However, it is not yet clear that this improvement is associated with a reduction in the incidence of pulmonary complications.
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Ann Acad Med Singap · Jul 1994
ReviewPharmacotherapy for cancer pain: an anaesthesiologist's viewpoint.
Cancer pain is prevalent and undertreated despite the availability of therapeutic options that, taken together are highly effective, economical and safe. Improved understanding of the pharmacology of chronically-administered opioids has resulted in reduced concerns about addiction and an increased emphasis on their use. The anaesthetist may play a pivotal role in cancer pain management by the provision of nerve blocks and other interventions, but, to be a truly effective consultant, must also be expert in all aspects of pharmacotherapy. A rationale for the development of pharmacologic expertise together with a review of assessment and pharmacologic management of cancer pain are provided.