British journal of anaesthesia
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Differences in the pharmacokinetics of propofol between male and female patients during and after continuous infusion have not been described in detail in patients aged 65 yr and older. To increase our insight into the pharmacokinetics of propofol in this patient population and to obtain pharmacokinetic parameters applicable in target controlled infusion (TCI), the pharmacokinetics of propofol during and after continuous infusion were studied in 31 ASA class 1 and 2 patients, aged 65-91 yr, scheduled for general surgery. Patients received propofol 1.5 mg kg(-1) i.v. in 1 min followed by 7 mg kg(-1) h(-1) until skin closure in the presence of a variable rate infusion of alfentanil during oxygen-air ventilation. ⋯ Gender significantly affected the pharmacokinetics of propofol. V3, Cl1 and Cl2 were significantly different between male and female patients, weight only affected Cl1. The pharmacokinetic parameters were: V1=4.88 litre, V2=24.50 litre, V3 (litre)=115+147 x gender (gender: male=1, female=2), Cl1 (litre min(-1))=-0.29+0.022 x weight+0.22 x gender, Cl2 (litre min(-1))=2.84-0.65 x gender (male=1, female=2), and Cl3=0.788 litre min(-1).
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of coagulation and blood loss during anaesthesia with inhaled isoflurane or intravenous propofol.
Propofol has been reported to affect blood coagulation. This prospective, randomized study compared coagulation and blood loss during anaesthetic maintenance with target-controlled intravenous propofol infusion vs. inhaled isoflurane. Thirty-eight ASA I-III patients undergoing head and neck surgery were allocated randomly to receive either inhaled isoflurane at end-tidal concentration 1-1.5% (group I, n=20) or target-controlled infusion (TCI) of propofol at target concentration 2-5 microg ml(-1) (group P, n=18). ⋯ Total blood loss was also not significantly different (median group I: 350 ml, range 20-1200 ml; group P: 200 ml, range 50-800 ml). Shortening of R-time and widening of angle developed over time in both groups (P<0.05 groups I and P, repeated measures ANOVA). We conclude that maintenance of anaesthesia with propofol TCI at 2-5 microg ml(-1) does not cause detectable coagulation changes on thrombelastography nor increase surgical blood loss when compared to inhaled isoflurane.
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Randomized Controlled Trial Clinical Trial
Effects of different concentrations of sevoflurane and desflurane on subcortical somatosensory evoked responses in anaesthetized, non-stimulated patients.
Twenty-four patients were recruited and given either sevoflurane or desflurane as their sole anaesthetic. Each patient was given sequentially increasing or decreasing doses at 0.5 MAC intervals, and the median nerve somatosensory evoked response recorded after an equilibration at each concentration. The N20-P25 and P25-N35 amplitudes decreased with increasing agent concentration. ⋯ The peak inflection points were at 3.2% for sevoflurane and 4.9% for desflurane. There were no differences between the ascending and descending groups. This increase in activity in the midbrain at 'surgical' end-tidal anaesthetic concentrations suggests more complex neuroelectrical responses to anaesthesia than simple global suppression.
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I report two patients undergoing open heart surgery, with nitrous oxide and isoflurane anaesthesia, for whom bispectral index (BIS) monitoring showed high BIS values with nitrous oxide and isoflurane anaesthesia. The BIS decreased immediately after nitrous oxide was stopped and increased again after nitrous oxide was restarted.