Anesthesia and analgesia
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Anesthesia and analgesia · Jun 1997
The effects of sevoflurane anesthesia on insulin secretion and glucose metabolism in pigs.
We investigated the effects of two different concentrations of sevoflurane, 0.4 minimum alveolar anesthetic concentration (MAC) and 1.0 MAC, on insulin secretion before, during, and after sevoflurane anesthesia using three successive intravenous glucose tolerance tests (IVGTT) in pigs with indwelling catheters. We also investigated changes in the levels of plasma glucose, catecholamines (epinephrine [E], norepinephrine [NE]), and cortisol (Cor). The pigs were grouped as awake, 0.4 MAC, or 1.0 MAC. ⋯ These decreases were quickly reversible (control levels were regained within 2 h of the end of anesthesia), were probably dose-related, appeared not to be mediated by E, NE, or Cor. In addition, the INS/GLU ratio 2.5-4 h after the end of anesthesia was significantly higher in the anesthetized groups than in the awake group. We conclude that sevoflurane anesthesia has a rapidly reversible inhibitory effect on basal and glucose-stimulated insulin secretion, as do other inhaled anesthetics, and might induce insulin resistance.
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Anesthesia and analgesia · Jun 1997
Comparative StudyThe effect of xenon on spinal dorsal horn neurons: a comparison with nitrous oxide.
We compared the effects of xenon (Xe) on the spinal cord dorsal horn neurons with those of nitrous oxide (N2O) in cats anesthetized with chrolarose and urethane. We assessed the potency of both anesthetics by the inhibition of wide dynamic range neuron responses evoked by cutaneous noxious (pinch) stimulation to a hindpaw. During 70% Xe inhalation, the responses of 7 of 11 neurons to pinch stimulation were suppressed. ⋯ After 20 min of Xe inhalation, the response to pinch was suppressed to 49.5% +/- 8.2% (mean +/- SE), while N2O, 70% in oxygen, suppressed it to 45.9% +/- 7.9%. The difference between N2O and Xe was not significant. We conclude that Xe and N2O suppress the spinal cord dorsal horn neurons to a similar degree.
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Anesthesia and analgesia · Jun 1997
Aprotinin but not tranexamic acid inhibits cytokine-induced inducible nitric oxide synthase expression.
Cell expression of inducible nitric oxide synthase (iNOS) is increased by cytokines, which results in high endogenous concentrations of nitric oxide (NO) and has been implicated in organ injury, including myocardial reperfusion injury. Serine protease inhibitors reduce cytokine-induced iNOS expression. The protease inhibitors aprotinin and tranexamic acid, which are used to reduce blood loss after cardiac surgery, were evaluated in vitro on cytokine-induced iNOS expression and the resulting NO production to demonstrate the relative antiinflammatory effects of each drug. ⋯ Consistent with the nitrite reduction, aprotinin significantly (P < 0.05) reduced cytokine-induced iNOS expression, while tranexamic acid had no effect. Aprotinin but not tranexamic acid reduces endogenous cytokine-induced NO production by inhibiting iNOS expression. Since increased endogenous NO concentrations secondary to iNOS activation have been implicated in organ injury, aprotinin may have clinical benefits when compared with tranexamic acid.
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Anesthesia and analgesia · Jun 1997
Cerebral hemoglobin and optical pathlength influence near-infrared spectroscopy measurement of cerebral oxygen saturation.
Near-infrared spectroscopy (NIRS) is a noninvasive optical technique to monitor cerebral oxygen saturation at the bedside. Despite its applicability, NIRS has had limited clinical use because of concerns about accuracy, noted by intersubject variability in slope and intercept of the line between NIRS- and weighted-average arterial-cerebrovenous saturation (SMO2). This study evaluated transcranial optical pathlength and cerebral hemoglobin concentration as sources for this intersubject variability. ⋯ By adjusting the NIRS algorithm with the cerebral hemoglobin measurements, slope and intercept remained unchanged by hemodilution. These data indicate that intersubject variability in NIRS originates, in part, from biologic variations in transcranial optical pathlength and cerebral hemoglobin concentration. Instruments to account for these factors may improve NIRS cerebral oxygen saturation measurements.