Anaesthesia
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The performance of breathing systems is tested by means of physical lung models. We describe a new lung model, allowing direct measurement of the dead space/tidal volume ratios produced by any breathing system at different fresh gas flows. The model allows a range of different patterns of spontaneous respiration to be studied. Although rebreathing is measured by capnography, the design ensures that the results are unaffected by changes in carbon dioxide inflow, or even calibration drift in the capnograph.
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We report an extremely rare complication of regional anaesthesia, a spinal subdural haematoma, which resulted in permanent neurological damage occurring 8 days after dural puncture at T12-L1. Although spinal subdural haematoma following spinal anaesthesia and lumbar puncture has been described before, this is the first report of this complication occurring after dural puncture using a 25 G atraumatic pencil point (Whitacre) needle. Contributory factors might have been the perioperative intermittent low dose aspirin therapy and the fact that spinal anaesthesia was performed at the T12-L1 level.
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A laboratory study of a new circle system is presented. The inspiratory limb encloses a coaxial tube, delivering fresh gas close to the patient, immediately upstream of the inspiratory one-way valve. ⋯ This is markedly improved by the new system. The advantages of the system are largely independent of respiratory pattern.