Anesthesia and analgesia
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Anesthesia and analgesia · Sep 1996
The effect of acute normovolemic hemodilution (ANH) on myocardial contractility in anesthetized dogs.
The influence of severe acute normovolemic hemodilution (ANH) on myocardial contractility (MC) was investigated in 14 splenectomized, anesthetized dogs. MC was assessed by the maximum rate of left ventricular pressure increase (LVdp/dt(max)), end-systolic elastance (Ees), and preload recruitable stroke work (PRSW) (conductance catheter, left ventricular pressure-volume relationship). Measurements of myocardial perfusion and oxygenation (radioactive microsphere technique) assured comparability of the model to previously performed studies. ⋯ Myocardial oxygen extraction as well as coronary venous Po2 were unaffected by ANH, while coronary venous lactate concentration decreased, indicating that myocardial oxygen need was met. LVdp/dt(max) decreased significantly after hemodilution (2278 +/- 577 vs 1884 +/- 381 mm Hg/s, P < 0.01), whereas Ees and PRSW increased significantly (1.76 +/- 0.54 vs 2.15 +/- 0.75 mm Hg/mL, P < 0.05, for Ees and 33 +/- 14 vs 45 +/- 14 mm Hg.mL, P < 0.05, for PRSW). While the decrease of LVdp/dt(max) most likely reflects ANH-induced changes of ventricular pre- and afterload, the increase of Ees and PRSW indicates a true increase of myocardial contractility during ANH in anesthetized dogs.
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Anesthesia and analgesia · Sep 1996
Randomized Controlled Trial Comparative Study Clinical TrialEnflurane decreases the threshold for vasoconstriction more than isoflurane or halothane.
Intraoperative hypothermia results largely from anesthetic-induced inhibition of tonic thermoregulatory vasoconstriction. Sufficient hypothermia, however, triggers peripheral vasoconstriction, which usually prevents further decrease in core temperature. The thermoregulatory effects of all volatile anesthetics have been tested in adults and/or children, but different anesthetics have not been directly compared. ⋯ Our data indicate that enflurane profoundly inhibits thermoregulatory responses in children. The mechanism for this extraordinary inhibition remains unknown but does not result from any obvious anesthetic pharmacology or thermoregulatory physiology. We conclude that unwarmed pediatric patients will become colder when anesthetized with enflurane than with halothane or isoflurane.
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Anesthesia and analgesia · Sep 1996
Randomized Controlled Trial Clinical TrialSpinal anesthesia with bupivacaine and fentanyl in geriatric patients.
We assessed the risks and benefits of the administration of fentanyl during spinal anesthesia in the elderly. Forty patients (70-83 yr) undergoing knee or hip replacement were studied. Preoperatively, cognitive function (minimental state examination [MMSE]), associated pathology, medications, and treatment were evaluated. ⋯ MMSE at hospital discharge was no different from preoperative values. Our results show that 25 micrograms of spinal fentanyl do not modify spinal anesthesia in the elderly, but induces pruritus and O2 desaturation. The decrease in postoperative pain intensity and the preservation of cognitive function would justify the use of spinal fentanyl in the elderly.