Anaesthesia
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We have studied the effects of nitrous oxide on the auditory evoked response index (AAI-index) derived from the A-line monitoring device during sevoflurane anaesthesia in 21 patients undergoing minor ambulatory surgery. During sevoflurane anaesthesia with an AAI-index < 30, the addition or withdrawal of nitrous oxide in a concentration of 66% end tidal did not show any linear dose dependent change in AAI-index. However, comparing nitrous oxide > 40% to nitrous oxide < 10% end tidal concentration the AAI-index did decrease, p < 0.05. The AAI-index is either non-linear at deeper anaesthetic levels or is insensitive to the anaesthetic effects of nitrous oxide in terms of MAC-multiples.
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To describe facilities for postoperative epidurals in UK National Health Service Hospitals, a questionnaire was sent to each hospital performing surgery below the head and neck. Of 271 hospitals, 256 replied (95%). While almost all offer postoperative epidurals, only 78 (30%) offer them to all surgical disciplines. ⋯ Levels of training in epidural care also vary widely. Two hundred and thirty-six hospitals (92%) have an acute pain team. Despite the expansion in acute pain services, facilities for postoperative epidurals are deficient in many NHS hospitals.
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Fifty patients scheduled for surgery under lumbar epidural anaesthesia were included in a study to evaluate the possibility of localising the epidural space solely by means of an acoustic signal. With an experimental set-up, the pressure generated during the epidural puncture procedure was translated into a corresponding acoustic signal. One anaesthetist held the epidural needle with both hands and detected the epidural space by means of this acoustic signal. ⋯ In all patients the epidural space was located with the acoustic signal. This was confirmed by conventional loss of resistance in 49 (98%) of the patients; in one patient (2%) it was not. We conclude that it is possible to locate the epidural space using an acoustic signal alone.