Journal of anesthesia
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Journal of anesthesia · Oct 1993
Effects of halothane and isoflurane anesthesia on sympathetic adrenal nerve responses to carbon dioxide challenge in rats.
We studied the influence of two volatile anesthetics, halothane and isoflurane, on the circulatory and sympathetic nerve responses to carbon dioxide (9% CO2) in rats. Systolic blood pressure was depressed throughout the CO2 challenge and after an initial reduction, a gradual increase was observed in heart rate. Sympathetic adrenal nerve action potentials (SANA) significantly increased in contrast to negative responses in the circulatory functions. ⋯ The maximum changes in SANA from the baseline values were 110% and 40% for the halothane and isoflurane groups, respectively. The sympathetic reflex response to hyperacapnia was retained at 1.5 MAC for both anesthetics, though isoflurane depressed these responses more markedly than halothane. Our results suggest that halothane is a more preferable anesthetic than isoflurane when viewed from the standpoint of preservation of sympathetic nerve response in such undesirable situations as severe hypercapnia occurring during anesthesia.
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Journal of anesthesia · Oct 1993
Naloxone and flumazenil fail to antagonize the isoflurane-induced suppression of dorsal horn neurons in cats.
Effects of naloxone and flumazenil on isoflurane activities were examined on dorsal horn neurons in cats. Isoflurane suppressed bradykinin-induced nociceptive responses in transected feline spinal cords. The bradykinin-induced neuronal firing rates were significantly suppressed by 60.0%, 35.3% and 32.2% at 10, 20 and 30 min after isoflurane administration, respectively. ⋯ The suppressive effects of isoflurane were not reversed by naloxone (0.2 mg.kg(-1), i.v.). Similarly, the benzodiazepine antagonist, flumazenil (0.2 mg.kg(-1), i.v.), did not affect the suppressive effects of isoflurane. Failure of naloxone and flumazenil to reverse the suppressive effects of isoflurane suggests that isoflurane interacts with neither opioid nor benzodiazepine receptors in producing its suppressive action on nociceptive responses in dorsal horn neurons of the feline spinal cord.
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Journal of anesthesia · Jul 1993
Differences in the assessment of postoperative pain when evaluated by patients and doctors.
This study was undertaken to compare the assessment of pain intensity by 59 patients and by their doctors according to a visual analogue scale (VAS) at rest and when coughing at 5 and 20 hr after major abdominal surgery. The rating given by the patients, who received epidural analgesia to relieve postoperative pain, was significantly above, and moreover, significantly correlated with that given by the doctors at any time or under any condition of the assessment. ⋯ Our findings indicate that the assessment of postoperative pain may be associated with some unreliability, especially during early periods, when using the subjective or objective-rated VAS at rest separately, and thus requires the combined use or the concomitant use of the VAS when coughing. Substitutional use of the objective-rated VAS for the subjective-rated VAS is not advised.