Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Changes in the auditory evoked potentials and the bispectral index following propofol or propofol and alfentanil.
Midlatency auditory evoked potentials (MLAEP) show graded changes with increasing doses of hypnotics but little change with opioids. The effect of their combination on the MLAEP was evaluated. Also, the bispectral index (BIS) was compared with the ability of MLAEP to correlate with sedation and predict loss of consciousness. ⋯ MLAEP changes, like the BIS, correlate well with increasing sedation produced by propofol, and these changes in the MLAEP are independent of the presence of an opioid. Among all the MLAEP parameters, Pa and Nb latencies are the best predictors of increasing sedation and loss of consciousness.
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Maintenance of airway patency and oxygenation are the main objectives of face-mask ventilation. Because the incidence of difficult mask ventilation (DMV) and the factors associated with it are not well known, we undertook this prospective study. ⋯ In a general adult population, DMV was reported in 5% of the patients. A simple DMV risk score was established. Being able to more accurately predict DMV may improve the safety of airway management.
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Body temperature often is ignored during regional anesthesia, despite evidence that hypothermia occurs commonly. Because hypothermia is associated with adverse clinical outcomes, it is important to recognize predictors of hypothermia and to monitor and control body temperature in patients at risk. The current study was designed to determine the predictors of core hypothermia in patients receiving spinal anesthesia for radical retropubic prostatectomy. ⋯ Although high-level spinal blockade has been associated with decreased thermoregulatory thresholds, no previous study has shown that a higher level of blockade is associated with a greater magnitude of core hypothermia in the clinical setting. As with general anesthesia, advanced age is associated with hypothermia during spinal anesthesia.
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Core hypothermia develops after the induction of general anesthesia, but intraoperative vasoconstriction usually prevents its progression. However, diabetes mellitus is often associated with autonomic neuropathy, which leads to abnormal peripheral neurovascular function. Accordingly, we tested the hypothesis that diabetic patients experience a greater reduction in core temperature during general anesthesia than nondiabetic patients. ⋯ The current results indicate that diabetic autonomic neuropathy is associated with more severe intraoperative hypothermia. We postulate that diabetic patients become more hypothermic because their peripheral neuropathy delays the onset of thermoregulatory vasoconstriction and reduces its efficacy once triggered. These patients may therefore fail to develop a normal core temperature plateau.
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FK506 binding protein is closely associated with the sarcoplasmic reticulum ryanodine receptor-channel and can modulate its function. The ryanodine receptor is stabilized by its association with FK506 binding protein. The immunosuppressant drugs FK506 (tacrolimus) and rapamycin can promote dissociation of FK506 binding protein from the ryanodine receptor 1 and by this mechanism increase sensitivity of ryanodine receptor 1 to agonists such as caffeine. Furthermore, it was shown recently that treatment of normal human skeletal muscle with FK506 and rapamycin increased halothane-induced contracture. The authors investigated the effect of the immunosuppressants FK506 and rapamycin on halothane-induced Ca2+ release in skeletal muscle sarcoplasmic reticulum vesicles. ⋯ Dissociation of FK506 binding protein from its binding site in skeletal muscle sarcoplasmic reticulum vesicles can modulate halothane-induced Ca2+ release through the ryanodine receptor. Data are discussed in relation to the role of the FK506 binding protein in modulating the effect of halothane on the ryanodine receptor and the development of malignant hyperthermia phenotype.