British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Emergence times from xenon anaesthesia are independent of the duration of anaesthesia.
Xenon (MAC = 71%) has an extremely low blood:gas partition coefficient (0.14). Therefore, we predicted that the rate of emergence from xenon anaesthesia would not be affected greatly by duration of anaesthesia. We studied 54 ASA I-II patients undergoing lower abdominal surgery who received equal MAC anaesthesia with 60% xenon, 60% nitrous oxide with 0.5% isoflurane or 60% nitrous oxide with 0.7% sevoflurane (n = 18 per group), each supplemented with extradural mepivacaine anaesthesia. ⋯ Mean emergence times from xenon anaesthesia were: T1, 3.3 (SD 1.0) min; T2, 3.6 (1.0) min; T3, 5.0 (1.1) min; and T4, 6.2 (1.7) min. These values were approximately 50% of those after nitrous oxide-sevoflurane anaesthesia (T1, 5.6 (1.4) min; T4, 10.5 (2.0) min). We conclude that xenon provided fast emergence from anaesthesia, regardless of the duration of anaesthesia.
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To clarify the anatomy of the extradural space of the thoracic spine, we have compared magnetic resonance (MR) images of the thoracic spine with those of the lumbar spine. In 20 healthy volunteers, T2-weighted axial MR images were obtained at the levels of the C7-T1, T7-8, T11-12 and L2-3 vertebrae. ⋯ At this level, the dura mater seemed to be in direct contact with the ligamentum flavum. Segmentation of the posterior extradural space was commonly observed at the L2-3 and T11-12 levels; however, incomplete segmentation of the posterior extradural space was often present at the T7-8 level.
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Comparative Study
Comparison of the effects of isoflurane with those of propofol on pulmonary vascular impedance in experimental embolic pulmonary hypertension.
Inhaled but not i.v. anaesthetics are reported to decrease pulmonary vascular resistance. The aim of this study was to compare the effects of isoflurane with those of propofol on the interaction between right ventricular (RV) function and the pulmonary vascular system in embolic pulmonary hypertension. Nine dogs received in random sequence propofol 18 mg kg-1 h-1 and 1.4% end-tidal isoflurane. ⋯ Compared with propofol, isoflurane at baseline did not affect PAP/Q plots, PVZ or hydraulic power data, but decreased dP/dtmax. After embolism, isoflurane shifted PAP/Q plots to lower PAP without affecting PVZ, did not affect hydraulic power data and decreased dP/dtmax. We conclude that in canine embolic pulmonary hypertension, isoflurane compared with propofol impeded RV vascular coupling caused by decreased RV contractility, while after-load remained unchanged despite some decrease in pulmonary vascular tone.