Journal of anesthesia
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Journal of anesthesia · Sep 1994
Effects of halothane and enflurane on the peripheral vasoconstriction and shivering induced by internal body cooling in rabbits.
General anesthetic agents have central and peripheral effects on body temperature regulation, and its alterations are related to the depth of anesthesia. To evaluate the effect of halothane and enflurane on thermoregulation, we investigated the threshold of body core temperatures to induce peripheral vasoconstriction and shivering in spontaneously breathing rabbits. Rabbits were anesthetized with halothane or enflurane at 0.0 (control), 0.2, and 0.4 MAC (minimum alveolar concentration). ⋯ The incidence of peripheral vasoconstriction was not significantly affected by halothane or enflurane. However, the incidence of shivering decreased in a dose-dependent fashion with both anesthetic agents. At 0.2 MAC, the incidence of shivering in the enflurane group was significantly higher than that in the halothane group, suggesting that suppression of shivering by halothane is stronger than enflurane.
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Journal of anesthesia · Sep 1994
Differential effects of halothane and enflurane on end-systolic pressure-diameter relationship in anesthetized, mechanically ventilated dogs.
To clarify the difference of negative inotropic effects, we evaluated the effects of 0, 0.5, and 1 MAC halothane and enflurane on systolic performance in anesthetized, mechanically ventilated, vagotomized dogs. Left ventricular myocardial contractility was assessed by the slope of the end-systolic pressure-diameter relationship (EES), which have been reported to be independent of alterations in preload and afterload but sensitive to changes in myocardial contractility. Both anesthetics decreased heart rate and dose-dependently decreased left ventricular systolic pressure. ⋯ TheEES was decreased with increasing concentrations of enflurane. TheEES was significantly larger (P<0.05) with 1 MAC of halothane than with 1 MAC enflurane. These results suggest that halothane preserves myocardial contractility better than enflurane in the presence of fentanyl.
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Journal of anesthesia · Sep 1994
Effects of dobutamine on the fatigued diaphragm: A comparison with dopamine.
We examined the effects of dopamine (DOA) 10 μg·kg(-1)·min(-1) I. V. and dobutamine (DOB) 10 μg·kg(-1). min(-1) I. V. on the contractility of the fatigued diaphragm in 26 anesthetized, mechanically ventilated dogs. ⋯ In each group, Pdi at both stimuli decreased after the cessation of administration. The integrated diaphragmatic electric activity (Edi) in the two groups did not change at any frequency of stimulation throughout the study. We conclude that DOB in comparison with DOA is more effective in improving the contractility of the fatigued diaphragm.