Anaesthesia
-
Comparative Study
The impact of low-risk intensive care unit admissions on mortality probabilities by SAPS II, APACHE II and APACHE III.
A large proportion of intensive care unit patients are low-risk admissions. Mortality probabilities generated by predictive systems may not accurately reflect the mortality experienced by subpopulations of critically ill patients. We prospectively assessed the impact of low-risk admissions (mortality risk < 10%) on the mortality estimates generated by three prognostic models. ⋯ Calibration for higher risk patients was similar for all three models but the APACHE III system calibrated worse than the other models for low-risk patients. This may have contributed to the poorer overall calibration of the APACHE III system (Hosmer-Lemeshow C-test: APACHE III chi(2) = 329; APACHE II chi(2) = 42; SAPS II chi(2) = 62). Imperfect characterisation of the large proportion of low-risk intensive care unit admissions may contribute to the deterioration of the models' predictive accuracies for the intensive care population as a whole.
-
Clinical Trial Controlled Clinical Trial
Does sevoflurane inhibit serum cholinesterase in children?
Serum cholinesterase activity was measured at induction, and following anaesthesia in 41 children aged between 4 and 30 months. The median exposure to sevoflurane was 273%.min. ⋯ The only change in cholinesterase activity detected was related to heamodilution. We conclude that plasma fluoride concentration following sevoflurane administration [13.8 (4.2) microm x l(-1)] is too low to exert an inhibiting effect on in vivo cholinesterase activity and that the previously reported decrease in mivacurium requirements during sevoflurane anaesthesia is unlikely to be due to inhibition by fluoride ions.
-
We studied the effects of adding 50% nitrous oxide to propofol anaesthesia administered by target-controlled infusion on middle cerebral artery flow velocity and autoregulatory indices derived from transient hyperaemic response tests. Nine healthy (ASA 1) adult patients scheduled to undergo elective surgery were recruited. A standardised anaesthetic comprising alfentanil 10 microg x kg(-1), propofol via a target-controlled infusion pump and vecuronium 0.1 mg x kg(-1) was used. ⋯ Propofol caused a significant decrease in MCA flow velocity and a significant increase in the strength of autoregulation. The addition of nitrous oxide had no significant effect on MCA flow velocity or cerebral autoregulation. These results suggest that addition of 50% nitrous oxide does not influence propofol-induced changes in cerebral haemodynamics.