Journal of anesthesia
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Journal of anesthesia · Dec 1996
Amrinone improves postischemic myocardial metabolism in the rat heart-lung preparation.
Amrinone, a phosphodiesterase inhibitor, is a non-glycosidic noncatecholamine with both vasodilator and positive inotropic effects. We were interested in assessing the effect of amrinone on postischemic cardiac performance in the isolated heart-lung preparation. Twenty-four male Wistar-ST rats were used. ⋯ Myocardial lactate, pyruvate, and glycogen levels were not significantly different among the groups. This result suggests that amrinone improves postischemic myocardial metabolism. Although we could not measure coronary flow, amrinone might increase coronary flow with direct coronary vasodilation which would have increased the myocardial ATP and energy charge levels.
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Journal of anesthesia · Dec 1996
Solubility of volatile anesthetics in plasma substitutes, albumin, intravenous fat emulsions, perfluorochemical emulsion, and aqueous solutions.
Using the gas chromatographic headspace sampling technique, we determined the solubility of volatile anesthetics (halothane, enflurane, isoflurane, and sevoflurane) in plasma substitutes, albumin solution, intravenous fat emulsions, perfluorochemical FC-43 emulsion, and aqueous solutions at 37°C. The order of magnitude of λ value (liquid/gas partition coefficients) was halothane >enflurane>isoflurane> sevoflurane in all the parenteral infusion fluids except the perfluorochemical emulsion (FC-43). ⋯ Also, the blood/gas partition coefficients in intravenous fat emulsions and FC-43 were calculated. It is suggested that fluid therapy, especially with intravenous fat emulsions or FC-43, may influence the blood/gas partition coefficients of anesthetics, and affect the induction of anesthesia.
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Journal of anesthesia · Dec 1996
Intraoperative contrast transesophageal echocardiography using Albunex.
This study was designed to investigate the effect of administration of the contrast material Albunex on intraoperative contrast transesophageal echocardiography for patients with mitral valve disease or coronary artery disease. We studied nine patients scheduled for elective coronary artery bypass grafting (CABG group) and nine patients scheduled for elective mitral valve replacement (MVR group), and used a transesophageal echocardiography probe and an echocardiographic system. During the period of stable hemodynamics before the start of cardiopulmonary bypass, Albunex in doses of 0.1 ml·kg-1 was injected at a rate of about 1 ml·s-1 from either the peripheral venous line or the distal lumen of the pulmonary arterial catheter, and the effect on contrast was compared. ⋯ In the CABG group, contrast resulting from administration of Albunex from the pulmonary arterial catheter was significantly better than that from the peripheral venous line, whereas in the MVR group, no improvement was found. Furthermore, when it was administered into the pulmonary artery, the effect on contrast for the MVR group was significantly lower than that for the CABG group. The efficacy rate of intraoperative contrast transesophageal echocardiography using Albunex was relatively low, and appeared to be affected by pulmonary circulation or many other factors such as the method of administration, including the route and injection pressure.
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Journal of anesthesia · Dec 1996
Protamine relaxes vascular smooth muscle by directly reducing cytosolic free calcium concentrations in small resistance arteries.
Protamine has been suggested to relax vascular smooth muscle by reducing the intracellular Ca2+ concentration ([Ca2+]i). However, there has been no direct evidence that protamine reduces the [Ca2+]i of vascular smooth muscle. We therefore studied the effects of protamine on changes in [Ca2+]i and tension induced by norepinephrine (NE) and high K+ in endothelium-denuded strips from rabbit small mesenteric artery, using fura-2-fluorometry and isometric tension recording methods. ⋯ Protamine concentration (15-500 μg·ml-1)-dependently inhibited (P<0.05) the phasic and tonic components of both NE- and high K+-induced contraction with IC50 values of ≈50 μg·ml-1. Protamine (50 μg·ml-1) inhibited (P<0.05) the phasic and tonic increases in [Ca2+]i caused by both NE and high K+ by ≈40%-60%. We conclude that the direct vasodilator action of protamine is due, at least in part, to reduction of [Ca2+]i in vascular smooth muscle; this reduction in [Ca2+]i may be due to inhibition of both Ca2+ influx and Ca2+ release from intracellular Ca2+ stores.
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Journal of anesthesia · Dec 1996
Hemodynamic effects of oral clonidine premedication in lumbar epidural anesthesia.
Clonidine, an α2-adrenergic agonist, has a potent sympatholytic effect and augments the pressor effect of ephedrine during general anesthesia. We evaluated whether oral clonidine premedication would alter the hemodynamic changes and enhance the pressor response to intravenous ephedrine during epidural anesthesia in 35 adult patients. They were randomly administered either premedication with clonidine approximately 5 μg·kg-1 po (n=17) or no clonidine medication (n=18). ⋯ There were no differences in blood pressure (BP) and heart rate values between groups during the onset of epidural anesthesia, except that BP before epidural anesthesia was lower in the clonidine group than the control group (P<0.05). The magnitude and duration of pressor responses to ephedrine were comparable between groups in awake and asleep states. In conclusion oral clonidine premedication 5 μg·kg-1 alters neither the hemodynamic changes nor the pressor response to intravenous ephedrine during epidural anesthesia.