European journal of anaesthesiology
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This study investigated the changes in the hypnotic component of anaesthesia, estimated by the bispectral index of the electroencephalogram, during normothermic cardiopulmonary bypass. Twenty-six patients (20 men, 6 women), aged 61 +/- 11 years (Mean +/- SD) scheduled for cardiac surgery were premedicated with hydroxyzine and meperidine. Anaesthesia was induced and maintained with a computer-controlled continuous infusion (not adjusted for haemodilution) of sufentanil (effect site concentration 0.4-0.6 ng mL-1) and a manually adjusted continuous infusion of propofol (4.4 +/- 1.8 mg kg-1 h-1). ⋯ Bispectral index values were 48 +/- 8 before cardiopulmonary bypass onset, 50 +/- 10 before, and 48 +/- 8 after end of cardiopulmonary bypass (P = NS). No patient had increases in bispectral index values during cardiopulmonary bypass consistent with awakening. We conclude that with the anaesthetic regimen presented in this study bispectral index values do not change during normothermic cardiopulmonary bypass.
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Comparative Study
The effects of fenoldopam on renal blood flow and tubular function during aortic cross-clamping in anaesthetized dogs.
Postoperative renal impairment is a recognized complication of infrarenal aortic cross-clamping. Fenoldopam, a selective dopamine agonist, may increase renal blood flow and decrease tubular oxygen consumption. The objective of this study was to quantify the effects of fenoldopam (0.1 microg kg-1 min-1) on renal blood flow and renal tubular function in anaesthetized dogs that have undergone aortic cross clamping. ⋯ The most striking abnormalities observed by electron microscopy were marked disruption of the microvillus brush border in proximal tubules, vacuolation and separation of epithelial cells on basolateral infolds. The changes were similar in the two groups. In conclusion fenoldopam (0.1 microg kg-1 min-1) may have renoprotective effects which persist during infrarenal aortic cross clamping.
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The effects of propofol and thiopental on three vasoconstrictors, acetylcholine, histamine, and serotonin were studied in isolated porcine and human coronary artery rings. Propofol and thiopental attenuated the contractile response to all mediators in a dose-dependent manner. This dilating effect was fairly weak using low concentrations (propofol 1 microg mL-1 and 10 microg mL-1, thiopental 5 microg mL-1 and 10 microg mL-1). ⋯ These dilating effects were seen both in intact and denuded rings, the differences were not significant. Human coronary artery segments were relaxed by thiopental (-22% to -76%) and propofol (-11% to -67%) to a similar extent. Our data indicate that propofol and thiopental relax isolated coronary segments in a dose-dependent manner, and that there is no evidence that these effects are dependent of endothelial factors.
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The aim of this study was to elucidate the influence of four neuromuscular blocking substances on coronary vascular tone using the model of isolated porcine coronary artery segments. We studied the effects of four muscle relaxants, atracurium, pancuronium, rocuronium, and vecuronium (0.1, 1, and 10 microg mL-1 each), on the contractile response to three vasoconstrictors: acetylcholine, histamine, and serotonin. ⋯ It is concluded that high-dose pancuronium exerts an antimuscarinic effect in vascular smooth muscle. The other neuromuscular agents studied do not alter vascular reactivity of isolated porcine coronary arteries.