Anesthesia and analgesia
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Anesthesia and analgesia · Mar 1995
Anesthesia with increasing doses of sufentanil and midlatency auditory evoked potentials in humans.
Our interest focused on the question whether sufentanil differs from alfentanil, fentanyl, and morphine with regard on its effects on midlatency auditory evoked potentials (MLAEP). Therefore, we studied MLAEP during general anesthesia with increasing doses of sufentanil in 16 patients scheduled for elective major urologic surgery. Anesthesia was induced with sufentanil (1 microgram/kg every 7 min to a total dose of 3 micrograms/kg). ⋯ For the amplitudes Na/Pa and Pa/Nb there was only a slight and statistically insignificant reduction. After the largest dose of sufentanil (3-5 micrograms/kg) Na and Pa showed a similar pattern as in awake patients. We conclude that sufentanil does not differ essentially from alfentanil, fentanyl, and morphine with regard on its effects on MLAEP.
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Anesthesia and analgesia · Mar 1995
Effects of intrathecal mu, delta, and kappa agonists on thermally evoked cardiovascular and nociceptive reflexes in halothane-anesthetized rats.
Despite significant opioid binding in the intermediolateral cell column, the effects of intrathecal injections of mu, delta, and kappa opioid agonists on the cardiovascular response to noxious stimulation have not been examined systematically. The pharmacology of intrathecally administered opioid agonists (mu, morphine, [D-Ala2,N-MePhe4,Gly5-ol]enkephalin (DAGO); delta, metkephamid, [D-Ala2-D-Leu5]enkephalin (DADL), [D-Pen2,D-Pen5]enkephalin (DPDPE); kappa, U50488H and PD117,302) or agonist-antagonist (nalbuphine) on somatomotor (tail-flick) and cardiovascular changes (blood pressure and heart rate) evoked by immersing the tail in 53 degrees C water were examined in rats anesthetized with halothane (0.75%) and in which intrathecal catheters had been chronically implanted. ⋯ In addition, intrathecal administration of mu and delta but not kappa or agonist-antagonist had little effect on resting heart rate and blood pressure. These data indicate that the agonist occupancy of spinal mu and delta, but not kappa agonists can profoundly modulate the autonomic and somatomotor response evoked by high threshold thermal stimuli.
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Anesthesia and analgesia · Mar 1995
Hemodilution impairs hypocapnia-induced vasoconstrictor responses in the brain and spinal cord in dogs.
Despite the increasing use of plasma expanders in the perioperative period, there have been few studies of cerebrovascular responsiveness during hemodilution. The present study was performed to evaluate the influence of isovolemic hemodilution on vasoconstrictor responses in the brain and spinal cord during hypocapnia. Sixteen mechanically ventilated, halothane-anesthetized dogs were randomly divided into two equal groups: Group 1, control group (hematocrit [Hct], 42% +/- 2%); Group 2, isovolemic hemodilution with 5% dextran 40 (Hct, 19% +/- 2%). ⋯ After hemodilution, hypocapnia had no significant effect on RVR in the cerebral cortex, cerebellum, pons, and medulla, and caused less pronounced increases in RVR within the spinal cord. We conclude that hemodilution either attenuated or completely abolished vasoconstrictor responses within the brain and spinal cord during hypocapnia. Furthermore, the present findings suggest that induced hypocapnia may be less effective as a clinical maneuver to reduce increased intracranial pressure during hemodilution.