Anesthesia and analgesia
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Anesthesia and analgesia · Aug 2005
Randomized Controlled Trial Clinical TrialDigital skin blood flow as an indicator for intravascular injection of epinephrine-containing simulated epidural test dose in sevoflurane-anesthetized adults.
I designed this study to determine the efficacy of heart rate (HR), systolic blood pressure (SBP), and digital skin blood flow (DSBF) in detecting intravascular injection after a simulated epidural test dose containing 15 mug of epinephrine in sevoflurane-anesthetized adults. In addition, the testing threshold using DSBF was derived. Eighty patients were randomized to receive either 0.5 minimum alveolar anesthetic concentration (MAC) sevoflurane or 1.0 MAC sevoflurane and nitrous oxide in oxygen (n = 40 for each sevoflurane concentration). Each group of patients was further randomized to receive either 3 mL of 1.5% lidocaine containing 15 mug of epinephrine IV or 3 mL of saline IV (n = 20 each). HR, SBP, and DSBF were monitored for 5 min after injection. By using the HR (positive if >or=10 bpm increase) and SBP (positive if >or=15 mm Hg increase) criteria, a positive response rate to epinephrine was 95% for both variables during 0.5 MAC and 90% during 1.0 MAC sevoflurane anesthesia. Injection of the test dose resulted in peak DSBF decrease by 87% +/- 8% and 81% +/- 12% at 52 +/- 10 and 53 +/- 13 s in the sevoflurane 0.5 and 1.0 MAC groups, respectively. Positive DSBF criterion, as determined from peak increases during saline administration, was a decrease in DSBF >or=15%. Using this value, the sensitivity, specificity, positive predictive value, and negative predictive value were 100% in both sevoflurane groups. In conclusion, DSBF was superior to conventional hemodynamic criteria for detection of an intravascular injection of epidural test dose. ⋯ This study examined the efficacy of digital skin blood flow to detect an intravascular injection of an epinephrine-containing epidural test dose. This new variable when measured with a laser Doppler flowmeter was superior to conventional hemodynamic criteria during sevoflurane anesthesia.
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Anesthesia and analgesia · Aug 2005
Comparative StudyThe comparative neurotoxicity of intrathecal lidocaine and bupivacaine in rats.
There is a considerable difference in the number of reports of neurologic injury in the literature between lidocaine and other local anesthetics. Few in vivo animal studies have produced convincing results showing a difference in neurotoxicity among anesthetics. We investigated whether lidocaine and bupivacaine differ with respect to sensory impairment and histologic damage when equipotent doses of the two are administered intrathecally in rats. First, to determine relative anesthetic potency, rats intrathecally received 20 muL of saline, 0.625%, 1.25%, 2.5%, or 5% lidocaine, or 0.125%, 0.25%, 0.5%, or 1.0% bupivacaine, and were examined with the tail-flick test for 90 min. The potency ratio calculated was approximately 1:4.70 (95% confidence interval, 3.65-6.07) for lidocaine/bupivacaine. In the next experiment, 45 rats intrathecally received 20 muL of saline, 2.13% bupivacaine (approximately 1.5 mg/kg), or 10% lidocaine (approximately 6.9 mg/kg), and were examined for persistent functional impairment and morphologic damage. Rats given lidocaine developed significantly more prolonged tail-flick latencies than those in other groups 4 days after injection and incurred more morphologic damage than those given saline or bupivacaine. In conclusion, although the doses of anesthetics administered were larger than those used clinically, the present results suggest that bupivacaine is less neurotoxic than lidocaine when administered intrathecally at equipotent concentrations in the rat model. ⋯ Bupivacaine induces less severe functional impairment and morphologic damage than lidocaine when the two anesthetics are intrathecally administered at equipotent concentrations in the rat.
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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
Case ReportsBrown-Séquard syndrome following removal of a cerebrospinal fluid drainage catheter after thoracic aortic surgery.
Neurological deficit remains a devastating complication of thoracic aortic surgery despite advances in methods to protect the spinal cord from ischemia. Various techniques have been used, including the combination of cerebrospinal fluid (CSF) drainage and distal aortic perfusion to decrease the incidence of postoperative neurological deficit. These deficits are usually bilateral and result in paraplegia. In this case report we present a patient with Type B aortic dissection and thoracoabdominal aortic aneurysm repair with insertion of a lumbar CSF drainage catheter. Postoperatively, the patient developed unilateral neurological features consistent with Brown-Séquard syndrome after removal of the CSF catheter. The lumbar cerebrospinal fluid catheter was reinserted and the CSF was drained. Medullary T6-7 signal abnormalities were seen on spinal cord magnetic resonance imaging, and we suggest that the spinal cord suffered a direct injury during catheter removal. The patient had an uneventful recovery. ⋯ We describe a patient who developed unilateral neurologic features suggestive of Brown-Sequard syndrome following removal of a cerebrospinal fluid catheter after thoracic aortic surgery. We suggest that the spinal cord was injured during catheter removal. The catheter was reinserted and the patient had a full neurologic recovery.
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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.