Anaesthesia
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Comparative Study
Measured pulmonary oxygen consumption: difference between systemic oxygen uptake measured by the reverse Fick method and indirect calorimetry in cardiac surgery.
Measurement of oxygen uptake by indirect calorimetry was compared with the reverse Fick method in a series of patients undergoing cardiac surgery. Oxygen uptake measurements for indirect calorimetry were made using a calibrated measurement system utilizing the Haldane transformation in a simple semiclosed breathing system based upon a modified Bain circuit. ⋯ Indirect calorimetry overestimated the reverse Fick value by 11.3% (p < 0.001). These results are consistent with the findings of previous studies in similar patient groups and are explained by lung tissue oxygen consumption.
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Multicenter Study
Failed tracheal intubation in obstetrics: no more frequent but still managed badly.
In the South-West Thames region of the United Kingdom, during a 5-year period from 1999 to 2003, there were 20 failed tracheal intubations occurring in 4768 obstetric general anaesthetics (incidence 1 : 238). In half of the 16 cases for which the patient's notes could be examined there was a failure to follow an accepted protocol for failed tracheal intubation.
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The role of vascular tone in determining cerebral perfusion pressure is increasingly being appreciated. It has been suggested that zero flow pressure, the arterial pressure at which blood flow ceases, represents the effective downstream pressure of the cerebral circulation. Nitrous oxide is a cerebral vasodilator and may therefore decrease zero flow pressure and increase cerebral perfusion pressure. ⋯ We studied eight healthy volunteers at normocapnia and studied the effects of the inhalation of nitrous oxide 50% on estimated cerebral perfusion pressure and zero flow pressure using transcranial Doppler ultrasonography. We found that nitrous oxide 50% significantly increased estimated cerebral perfusion pressure (p = 0.03), whilst decreasing zero flow pressure (p = 0.01). These results suggest that the vasomotor effects of nitrous oxide predominate in determining the effective downstream pressure of the cerebral circulation in healthy individuals.
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A survey of the members of the Neuroanaesthesia Society of Great Britain and Ireland was conducted to examine issues arising from the management of long cases. Replies were received from 47% of neuroanaesthetists. ⋯ These pressures are likely to increase as the European Working Time Directive reduces the availability of trainees, and because of expansion in neurosurgery and neuroradiology. Similar concerns are likely to extend into other anaesthetic specialties with long-duration cases and may apply to our surgical colleagues.