British journal of anaesthesia
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Infusion of propofol by a target-controlled infusion (TCI) system is effective in achieving conscious sedation for anxious patients presenting for dental surgery. It is a common clinical observation that anxious patients require more anaesthetic drugs than non-anxious individuals. In study 1 we have defined blood propofol concentrations necessary for conscious sedation in both anxious (n = 23) and non-anxious (n = 18) patients. ⋯ In study 2, an optimized set of microconstants was derived which should more accurately predict the pharmacokinetic profile of the anxious population and this set was tested prospectively in another group of 12 anxious dental patients. Bias and precision with the optimized kinetic set were significantly less than the values obtained in study 1. We conclude that there was no significant pharmacokinetic differences between anxious and non-anxious subjects receiving subanaesthetic doses of propofol for conscious sedation.
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Comment Letter Case Reports
Sevoflurane for difficult intubation in children.
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Thrombelastography (TEG) correlates with postoperative chest drain output in patients undergoing cardiopulmonary bypass (CPB). In vitro incubation with heparinase allows TEG monitoring during CPB, despite heparin anticoagulation. Hypothermia impairs coagulation, but these effects cannot be assessed by standard coagulation tests performed at 37 degrees C. ⋯ Maximum amplitude (MA), reflecting absolute clot strength, was not affected at temperatures of 33-37 degrees C. These findings indicate a decrease in the speed of clot formation, but not absolute deterioration in clot quality. Furthermore, heparinase-modified TEG indicated that there were nine cases in which heparin effects persisted after heparin reversal with protamine, providing a rational guide to protamine therapy.
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We have assessed the effects of overinflation on surfactant function and composition in rats undergoing ventilation for 20 min with 100% oxygen at a peak inspiratory pressure of 45 cm H2O, with or without PEEP 10 cm H2O (groups 45/10 and 45/0, respectively). Mean tidal volumes were 48.4 (SEM 0.3) ml kg-1 in group 45/0 and 18.3 (0.1) ml kg-1 in group 45/10. ⋯ Group 45/0 had an increase in non-active to active total phosphorus compared with nonventilated controls (0.90 (0.16) vs 0.30 (0.07)). We conclude that ventilation in healthy rats with peak inspiratory pressures of 45 cm H2O without PEEP for 20 min caused severe impairment of pulmonary surfactant composition and function which can be prevented by the use of PEEP 10 cm H2O.