British journal of anaesthesia
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Nitric oxide synthase requires tetrahydrobiopterin for its activity. In animal models of sepsis, changes in circulating tetrahydrobiopterin concentrations precede increases in nitrate. We measured plasma tetrahydrobiopterin and nitrate concentrations on three consecutive days in 10 patients with septic shock and 10 critically ill control patients. ⋯ In patients with septic shock, both tetrahydrobiopterin and total nitrate concentrations were higher than those in critically ill controls but were increased mainly in patients with renal failure. In summary, tetrahydrobiopterin concentration increases during septic shock, in line with increases in nitrate concentration. However, as for nitrate, concentrations
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Randomized Controlled Trial Clinical Trial
Biphasic EEG changes in relation to loss of consciousness during induction with thiopental, propofol, etomidate, midazolam or sevoflurane.
The time course of four EEG effect variables, amplitude in the 2-5 Hz and in the 11-15 Hz band, spectral edge frequency 95% (SEF95), and bispectral index (BIS), in response to increasing concentrations of thiopental, propofol, etomidate, midazolam, or sevoflurane during a 10 min induction of anaesthesia was studied in 25 patients to determine the existence of a biphasic effect and to study the relationship of the EEG effect to the moment of loss of consciousness. A biphasic effect, that is, an initial increase of the effect variable followed by a decrease at higher concentrations, during the transition from consciousness to unconsciousness was found in EEG amplitude (both frequency bands) and in SEF95 for all anaesthetics except midazolam. ⋯ There was no consistent relationship between the time of occurrence of the peak EEG effect, or the value of the EEG variable and the moment of loss of consciousness. With rapidly changing drug concentrations during the induction of anaesthesia, none of these EEG effect variables could be correlated to the moment of loss of consciousness.