Journal of anesthesia
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Journal of anesthesia · Mar 1998
Effects of reduction of carrier gas flow rate on sevoflurane and isoflurane consumption and costs.
To evaluate whether sevoflurane and isoflurane consumption would be actually halved by halving the carrier gas flow rate, as predicted by a theoretical model, we measured the consumed volume of liquid sevoflurane and isoflurane and total costs of anesthetic gas at carrier gas flow rates of 3 and 61·min-1. ⋯ Halving the carrier gas flow rates halved the consumption of isoflurane but not of sevoflurane, indicating that factors other than carrier gas flow rates are involved in determining consumption in the clinical setting.
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Journal of anesthesia · Mar 1998
Middle-ear pressure variations during total intravenous anesthesia with propofol, fentanyl, and ketamine.
As the middle-ear cavity is one of the noncompliant gas-filled cavities, an increase in middle-ear pressure (MEP) instead of volume expansion is observed with inhalation of nitrous oxide (N2O). Changes in MEP cause many complications, such as ear pain, temporary hearing impairment, and postoperative emesis. Therefore, we investigated changes in MEP during total intravenous anesthesia (TIVA) with propofol, fentanyl, and ketamine (PFK) and inhalation of N2O. ⋯ PFK had a minimal effect on MEP, whereas addition of N2O to PFK increased MEP dramatically. Therefore, TIVA, or at least PFK, would be a better choice for patients with middle-ear or upper-airway diseases.
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Journal of anesthesia · Mar 1998
Differential vascular reactivity of canine mesenteric arteries and veins to sevoflurane.
The aim of this study was to compare the vascular reactivities of canine mesenteric arteries and veins to sevoflurane and to elucidate the underlying mechanism that is responsible for sevoflurane-induced hypotension. ⋯ Sevoflurane attenuated the contractile responses to transmural ES in veins but not in arteries. The concentration responses to NE were not affected by sevoflurane in arteries or in veins. At stable precontraction induced by NE, when sevoflurane was placed in the bathing medium, arteries with intact endothelium had significant contraction at 1.7% and 3.4% sevoflurane, followed by relaxation at 5.1%. On the contrary, sevoflurane produced dose-dependent relaxation in endothelium-denuded arteries and endothelium-intact veins CONCLUSION: It is suggested that the relaxation of the veins by sevoflurane may be due to the inhibition of NE release from sympathetic nerve endings and to the direct inhibition of the contractile mechanisms of vascular smooth muscle. In arteries, sevoflurane causes endothelium-dependent vasocontraction, probably by inhibiting the release of basal endothelium-derived relaxing factor (EDRF).
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Journal of anesthesia · Mar 1998
Thoracic epidural blockade preserves left ventricular early diastolic filling assessed by transesophageal echocardiography.
The objective of this study was to examine the effect of thoracic epidural anesthesia (TEA) on left ventricular systolic and diastolic function assessed by transesophageal echocardiography under general anesthesia. ⋯ High TEA reduces fractional shortening without any changes in preload and afterload, indicating impairment of systolic function, but early peak velocity, deceleration rate, and deceleration time, which are the indices of diastolic function, are not changed during high TEA combined with general anesthesia.