Anesthesia and analgesia
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Anesthesia and analgesia · Aug 2005
Clinical TrialThe effects of sevoflurane and hyperventilation on electrocorticogram spike activity in patients with refractory epilepsy.
We investigated the effects of sevoflurane and hyperventilation on intraoperative electrocorticogram (ECoG) spike activity in 13 patients with intractable epilepsy. Grid electrodes were placed on the brain surface and ECoG was recorded under the following conditions: 1) 0.5 minimal alveolar anesthetic concentration (MAC) sevoflurane, 2) 1.5 MAC sevoflurane, and 3) 1.5 MAC sevoflurane with hyperventilation. The number of spikes per 5 min and the percentage of leads with spikes were assessed in each condition. In 4 patients with chronically implanted-subdural electrodes, the leads with seizure onset and with spikes during the interictal periods in the awake state were compared with those during sevoflurane anesthesia at 0.5 MAC and 1.5 MAC. The number of spikes and the percentage of leads with spikes were significantly more under 1.5 MAC sevoflurane anesthesia compared with those under 0.5 MAC sevoflurane (P < 0.05). The induction of hyperventilation significantly increased the number of spikes and percentage of leads with spikes (P < 0.05). With 0.5 MAC sevoflurane, the leads with spikes were similar to those at seizure onset in the awake state, whereas with 1.5 MAC sevoflurane, spikes were similar to those occurring during interictal periods in the awake state. These results indicate that sevoflurane and hyperventilation can affect the frequency and extent of ECoG spike activity in patients with intractable epilepsy. Careful attention should be paid to the concentration of sevoflurane used and ventilatory status when intraoperative EcoG is used to localize epileptic lesions. ⋯ Electrocorticogram can be used to define the location and extent of epileptic foci during epilepsy surgery. However, electrocorticogram can be affected by anesthetic technique. The present study found that sevoflurane concentration and hyperventilation affected the frequency and the extent of electrocorticogram spike activity in epileptic patients.
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Anesthesia and analgesia · Aug 2005
Beta3-containing gamma-aminobutyric acidA receptors are not major targets for the amnesic and immobilizing actions of isoflurane.
Mice bearing an N265M point mutation in the gamma-aminobutyric acid (GABA)(A) receptor beta3 subunit resist various anesthetic effects of propofol and etomidate. They also require a 16% larger concentration of enflurane and a 21% larger concentration of halothane to abolish the withdrawal reflex than do wild-type mice. Using a Pavlovian test, we measured whether this mutation increased the concentration of isoflurane required to impair learning and memory relative to wild-type mice. We found that the concentration was not significantly increased. We also measured MAC (the minimum alveolar concentration required to eliminate movement in response to noxious stimulation in 50% of subjects). Isoflurane MAC for mutant mice (1.93% +/- 0.0.03%; mean +/- se; n = 14) was 17.0% larger than MAC for wild-type mice (1.65 +/- 0.04; n = 14; P < 0.001). Similarly, the cyclopropane MAC for mutant mice (27.6% +/- 0.55%; n = 16) was 13.6% larger than MAC for wild-type mice (24.3 +/- 0.46; n = 8; P < 0.01). The increase in MAC for cyclopropane was unexpected, because published reports find only minimal actions at alpha1beta2gamma2 GABA(A) receptors whereas isoflurane provides a large enhancement. Consistent with previous work on alpha1beta2gamma2 GABA(A) receptors, we found in Xenopus oocytes that 5 MAC cyclopropane enhanced the effect of GABA on alpha1beta2gamma2 GABA(A) receptors by only 76%, and by a nearly identical enhancement in alpha1beta3gamma2, and alpha6beta3gamma2 receptors. In contrast, a much smaller concentration of isoflurane (1 MAC) produced a 160% to 310% enhancement in these receptors. If, relative to isoflurane, cyclopropane minimally increases GABA-induced chloride currents at any GABA(A) receptor subtype, the present data for MAC are consistent with the notion that GABA(A) receptors do not mediate the immobility produced by inhaled anesthetics. ⋯ The results of the present study indicate that beta3-containing gamma-aminobutyric acidA receptors do not mediate the amnesia produced by isoflurane and do not mediate, or only partially mediate, the immobility produced by inhaled anesthetics.
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Anesthesia and analgesia · Aug 2005
Randomized Controlled Trial Comparative Study Clinical TrialNarcotrend or bispectral index monitoring during desflurane-remifentanil anesthesia: a comparison with a standard practice protocol.
Bispectral Index (BIS) (Aspect Medical Systems, Newton, MA) and Narcotrend (MonitorTechnik, Bad Bramstedt, Germany) are monitoring devices that were, as others, designed to assess the depth of anesthesia. Meanwhile, a number of studies indicate that with total IV anesthesia, BIS and Narcotrend have comparable effects on drug consumption and recovery times whereas comparative clinical data for volatile anesthetics are still missing. Therefore, we designed the present prospective, randomized, and double-blinded study to compare the effects of BIS and Narcotrend monitoring during desflurane-remifentanil anesthesia and versus a standard anesthetic practice protocol. One-hundred-twenty adult patients scheduled for minor orthopedic surgery were randomized to receive a desflurane-remifentanil anesthetic controlled either by Narcotrend or by BIS or solely by clinical variables. Anesthesia was induced with 0.4 microg x kg(-1) x min(-1) remifentanil and 2 mg/kg propofol. After tracheal intubation, remifentanil was infused at a constant rate of 0.2 microg x kg(-1) x min(-1) whereas desflurane in 1.5 L/min O(2)/air was adjusted according to clinical variables or the following target values: during maintenance of anesthesia to a value of "D(0)" (Narcotrend) or "50" (BIS), 15 min before the end of surgery to "C(1)" (Narcotrend) or "60" (BIS), whereas in the standard protocol group, desflurane was controlled according to clinical variables, e.g., heart rate, arterial blood pressure, movements. Recovery times and desflurane consumption were recorded by a blinded investigator. The desflurane vaporizer was weighed before and after anesthesia and consumption per minute was calculated. Data are mean +/- sd. The groups were comparable for demographic data, duration of anesthesia, and mean remifentanil dosages. Compared with standard practice, patients with Narcotrend or BIS monitoring needed significantly less desflurane (standard practice 443 +/- 71 mg/min, Narcotrend 374 +/- 124 mg/min, BIS monitoring 416 +/- 99 mg/min desflurane [both P < 0.05]). However, recovery times were not significantly different between the groups, e.g., opening of eyes 4.7 +/- 2.2 versus 3.7 +/- 2.0 versus 4.2 +/- 2.1 min. During desflurane-remifentanil anesthesia, Narcotrend and BIS monitoring seem to be equally effective compared with standard anesthetic practice: BIS and Narcotrend allow for a small reduction of desflurane consumption whereas recovery times are only slightly reduced. ⋯ Monitoring the electroencephalogram with Narcotrend or Bispectral Index during desflurane-remifentanil anesthesia only slightly reduces recovery times when compared with a standard practice protocol.
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Anesthesia and analgesia · Aug 2005
Randomized Controlled Trial Comparative Study Clinical TrialIntraarticular patient-controlled regional anesthesia after arthroscopically assisted anterior cruciate ligament reconstruction: ropivacaine/morphine/ketorolac versus ropivacaine/morphine.
Anterior cruciate ligament reconstruction (ACLR) is associated with moderate to severe postoperative pain. We compared the intraarticular analgesic effects of ropivacaine and morphine with or without ketorolac and the need for rescue IV morphine at rest and during movement in patients undergoing anterior cruciate ligament reconstruction during spinal anesthesia. Thirty-nine patients receiving intraarticular patient-controlled regional analgesia with a 10-mL bolus and a 60-min lockout interval were randomized into 3 groups: the RM group received 0.25% ropivacaine and morphine 0.2 mg/mL; the RMK group received 0.25% ropivacaine, morphine 0.2 mg/mL and ketorolac 1 mg/mL; the P group received saline. Analgesic mixtures were prepared in 100-mL bags and coded. If needed, rescue morphine 2 mg was self-administered IV with 10-min lockout intervals. Pain scores and patient satisfaction were assessed at rest and during movement. There were no significant differences among the groups in pain scores and patient satisfaction. Daily morphine consumption was significantly smaller in the RMK group (8 +/- 8 mg) compared with the RM group (23 +/- 20 mg; P = 0.002) and in both groups compared with control (46 +/- 21 mg; P < 0.001). We conclude that intraarticular patient-controlled regional analgesia provides effective pain relief after anterior cruciate ligament reconstruction. The combination of intraarticular ropivacaine, morphine, and ketorolac was superior to control or to a combination of ropivacaine and morphine. ⋯ This study showed the feasibility and efficacy of intraarticular patient-controlled regional analgesia technique for pain relief after anterior cruciate ligament reconstruction. The combination of intraarticular ropivacaine, morphine, and ketorolac was superior to control or to a combination of ropivacaine and morphine.