Anesthesia and analgesia
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Anesthesia and analgesia · Mar 2000
No implicit memory for stories played during isoflurane/alfentanil/nitrous oxide anesthesia: a reading speed measurement.
Implicit memory of intraoperatively presented stories was recently detected by using the reading speed paradigm during propofol-alfentanil-nitrous oxide anesthesia. Our main goal was to evaluate the reading speed test procedure under another anesthetic regimen, i.e., isoflurane combined with nitrous oxide and alfentanil-infusion. In both experiments, patients were premedicated with oral midazolam. In a previous experiment, patients postoperatively read "old" stories that had been presented during anesthesia quicker compared with "new," unpresented stories. The same study design and test material as in the previous experiment were used. One of two audio tapes with two short stories was played randomly to patients during lumbar disk surgery and to awake controls. Approximately 7 h later, a structured interview and the reading speed test were used to determine whether the participants had any explicit or implicit memories of the presented stories. The results of 30 patients and 30 controls were calculated. Whereas the control participants showed an intact explicit and implicit memory of the previously presented material, no such effect was found in the anesthetized patients. The present experiment shows that changing the main anesthetic in otherwise equal study conditions, i. e., propofol to isoflurane (end-expiratory 0.7%), implicit memory is abolished in anesthetized patients. ⋯ We showed that implicit memory during general anesthesia can be abolished by changing the hypnotic anesthetic. Increased postoperative reading speed for stories presented during propofol-alfentanil-nitrous oxide anesthesia was shown in a previous experiment, but not in our study using isoflurane for balanced anesthesia.
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Anesthesia and analgesia · Mar 2000
Randomized Controlled Trial Clinical TrialSedative, amnestic, and analgesic properties of small-dose dexmedetomidine infusions.
This research determined the safety and efficacy of two small-dose infusions of dexmedetomidine by evaluating sedation, analgesia, cognition, and cardiorespiratory function. Seven healthy young volunteers provided informed consent and participated on three occasions with random assignment to drug or placebo. Heart rate, blood pressure, respiratory rate, ETCO(2), O(2) saturation, and processed electroencephalogram (bispectral analysis) were monitored. ⋯ IMPLICATIPNS: The alpha(2) agonist, dexmedetomidine, has sedation and analgesic properties. This study quantified these effects, as well as cardiorespiratory, memory and psychomotor effects, in healthy volunteers. Dexmedetomidine infusions resulted in reversible sedation, mild analgesia, and memory impairment without cardiorespiratory compromise.
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Anesthesia and analgesia · Mar 2000
Randomized Controlled Trial Comparative Study Clinical TrialA comparison of epidural levobupivacaine 0.75% with racemic bupivacaine for lower abdominal surgery.
Levobupivacaine, the S(-) isomer of bupivacaine, is less cardiotoxic than racemic bupivacaine. In this prospective, randomized, double-blinded study of epidural anesthesia, the onset, extent, and duration of sensory and motor block produced by 0.75% levobupivacaine (20 mL, 150 mg) was compared with that of 0.75% racemic bupivacaine in 56 patients undergoing elective lower abdominal surgery. The time to onset of adequate sensory block (T10 dermatome) was similar in both treatment groups (13.6 +/- 5.6 min for levobupivacaine and 14.0 +/- 9.9 min for bupivacaine), with an average peak block height of T5 reached at 24.3 +/- 9.4 and 26.5 +/- 13.2 min, respectively. Time to complete regression of sensory block was significantly longer with levobupivacaine (550.6 +/- 87.6 min) than bupivacaine (505.9 +/- 71.1 min) (P = 0.016). Abdominal muscle relaxation was adequate for the scheduled procedure in all patients, and there were no significant differences between the groups in rectus abdominis muscle scores (P = 0.386) and quality of muscle relaxation as determined by the surgeon and anesthesiologist (P = 0. 505 and 0.074, respectively). In conclusion, both 0.75% levobupivacaine and 0.75% bupivacaine produced effective epidural anesthesia and their effects were clinically indistinguishable. ⋯ The results of this study indicate that the sensory and motor block produced by 0.75% levobupivacaine is equivalent to that of 0.75% racemic bupivacaine. Both local anesthetics are well tolerated and effective in producing epidural anesthesia for patients undergoing lower abdominal surgery.