Journal of neurosurgical anesthesiology
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J Neurosurg Anesthesiol · Jan 1999
Comparative StudyInhibition of nitric oxide metabolism enhances the hypnotic-anesthetic action of the alpha2-adrenoceptor agonist dexmedetomidine in vivo.
Nitric oxide (NO) synthase inhibitors have been demonstrated to increase the anesthetic action of volatile and intravenous anesthetics. This study was designed to test the hypothesis that, comparable to other general anesthetics, the hypnotic-anesthetic action of dexmedetomidine is increased after administration of the NO synthase inhibitor nitro-L-arginine methyl ester (L-NAME). With approval of the local animal care committee, the anesthetic potency of dexmedetomidine or a combination of dexmedetomidine plus 1 mM L-NAME was determined in Xenopus laevis larvae. ⋯ Administration of D-NAME did not affect the EC50 of dexmedetomidine. In a manner comparable to that of other general anesthetics, the anesthetic effect of dexmedetomidine was increased by about 51% by an acute inhibition of the NO metabolism. Together with recent findings that alpha2-adrenoceptor agonists decrease the NO mediated synthesis of cGMP similar to volatile and intravenous anesthetics, the results suggest that the NO/cGMP pathway is an important mediator of the anesthetic action of these compounds.
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J Neurosurg Anesthesiol · Jan 1999
Is there paradoxical arousal reaction in the EEG subdelta range in patients during anesthesia?
Different anesthetic drugs can produce different electroencephalographic (EEG) patterns. Nondrug induced influences, such as surgical stimulation, may also alter the EEG in anesthetized patients. Increases of delta activity are interpreted as signs of deepening of anesthesia. ⋯ On the other hand, in the subdelta range (the 0.05-1 Hz and 1-2 Hz frequency bands), there was an opposite reaction. This significant (p<0.001, according to ANOVA and Dunn's method) reduction of EEG power as a result of the surgical stimuli was found in 25 patients (mean age, 49.1+/-16.3 years) scheduled for elective neurosurgical intervention in the lumbosacral region. This report shows some of the problems arising from the common practice of arbitrarily subdividing a power spectrum in frequency bands.
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J Neurosurg Anesthesiol · Jan 1999
Comparative StudyEffects of postischemic halothane administration on outcome from transient focal cerebral ischemia in the rat.
This study examined the effect of prolonged postischemic halothane administration on outcome from transient focal cerebral ischemia in rats. Conscious normothermic rats were subjected to 75 minutes of filament middle cerebral artery occlusion (MCAO). Animals were then divided into two groups. ⋯ Cortical (Awake = 76+/-57 mm3; Halothane = 90+/-57 mm3; p = 0.494, mean +/- standard deviation), subcortical (Awake = 71+/-33 mm3; Halothane = 80+/-35 mm3; p = 0.472), and total (Awake = 147+/-88 mm3; Halothane = 171+/-91 mm3; p = 0.477) infarct volumes were not significantly different between groups. The data indicate that postischemic halothane administration offers no benefit in ameliorating damage from focal cerebral ischemia. This suggests that the neuroprotective effect of halothane observed in other studies is consistent with influences on intra-ischemic pathophysiology only.
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J Neurosurg Anesthesiol · Jan 1999
Fiberoptic intubation in 327 neurosurgical patients with lesions of the cervical spine.
In patients with lesions of the cervical spine, direct laryngoscopy for endotracheal intubation entails the risk of injuring the spinal cord. In an attempt to avoid this complication, the authors used flexible fiberoptic nasal intubation in a series of 327 patients with cervical lesions undergoing elective neurosurgical procedures. The nasal route was preferred for laryngeal intubation because it is easier than the oral route and a restraining collar or halo device does not impair the intubating maneuver. ⋯ Cervical stabilizers did not have to be removed for intubation in any patient. None of the patients had postoperative neurologic deficits attributable to the intubation procedure. The authors consider fiberoptic transnasal intubation to be a useful alternative to direct laryngoscopic tracheal intubation in patients undergoing elective surgical procedures on the cervical spine to avoid potential injury to the cervical spinal cord.
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J Neurosurg Anesthesiol · Jan 1999
Comparative StudyCerebral glucose metabolism in acute and persistent vegetative state.
Regional cerebral glucose metabolism (rCMRglc) was investigated with 18F-2-fluoro-2-deoxy-D-glucose (FDG) and positron emission tomography (PET) in 24 patients with acute (AVS, duration <1 month, n=11) or persistent (PVS, duration >1 month, n=13) vegetative state (VS) following prolonged anoxia due to cardiorespiratory arrest. After a follow-up period of twelve months, 8 patients had died, 13 remained in a permanent vegetative state and three showed moderate improvement of consciousness, without however regaining independence for activities of daily life. As expected, overall glucose utilization (CMRglc) was significantly reduced in VS in comparison to age matched controls. ⋯ A statistically significant correlation between the degree of evoked potential or EEG alterations in VS and the reduction of global or regional cortical metabolic rates for glucose could not be established. Cortical metabolic rates in patients with PVS were significantly reduced when compared to patients studied in AVS (p<0.05 for all cortical regions of interest except the frontal lobe). This phenomenon reflects the progressive loss of residual cortical function following anoxic brain injury that corresponds to the neuropathological findings of progressive Wallerian and transsynaptic degeneration as sequelae of anoxic brain injury in PVS.