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*Department of Anesthesia, South Carelia Central Hospital, Lappeenranta, Finland;
Department of Anesthesia, Tampere University Hospital, Tampere, Finland;
Department of Chemistry, Tampere University Hospital, Tampere, Finland;
Department of Pharmacology, University of Turku, Turku, Finland;
||School of Public Health, University of Tampere, Tampere, Finland;
¶School of Public Health, Research Unit, Tampere University Hospital, Tampere, Finland; and
#Ragnar Granit Institute, Tampere University of Technology, Tampere, Finland
Address correspondence and reprint requests to Seppo T. Mustola, MD, Department of Anesthesia, South Carelia Central Hospital, Valto Käkelän Katu 1, FIN-53130 Lappeenranta, Finland. Address e-mail to seppo.mustola{at}ekshp.fi
The electroencephalographic burst suppression pattern (BSP) might indicate the brains effect-site concentration of anesthetics more precisely than clinical signs and thus eliminate bias from studies on the reaction to tracheal intubation after different induction drugs. To test this hypothesis, we compared the catecholamine and cardiovascular responses and their variances to tracheal intubation when either BSP was induced by infusion of propofol (30 mg · kg-1 · h-1; n = 14) or thiopental (75 mg · kg-1 · h-1; n = 14) or anesthesia by repeated bolus doses until loss of reflexes (LR), initially of propofol 2.5 mg/kg (n = 15) or thiopental 5 mg/kg (n = 15). The standard deviations were more often smaller in the BSP than in the LR groups, but the results of Levenes test for differences of variance were insignificant. At the LR level, propofol attenuated catecholamine, arterial blood pressure, and heart rate responses to intubation better than thiopental, but at the BSP level, only the norepinephrine response was better attenuated. Cp50 concentrations of propofol and thiopental at the onset of BSP were 9.65 and 31.60 µg/mL, respectively.
IMPLICATIONS: Our results did not support the hypothesis that the responses to tracheal intubation can be more accurately predicted when unconsciousness is controlled with the aid of an electroencephalographic burst suppression pattern. Significant differences were found in the reactions between propofol and thiopental. At the burst suppression level, the catecholamine response was abolished with propofol.
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