Journal of neurosurgical anesthesiology
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J Neurosurg Anesthesiol · Apr 1997
Comparative StudyPredictive accuracy of continuous propofol infusions in neurosurgical patients: comparison of pharmacokinetic models.
The performance of 10 pharmacokinetic models in predicting blood propofol concentrations was evaluated in patients during neurosurgical anesthesia. Eight patients-ASA category I or II, aged 49 +/- 18-years, weighing 71 +/- 20 kg, and scheduled for routine neurosurgery-were anesthetized with propofol and sufentanil using Ohmeda pumps controlled with a personal computer. Sufentanil was administered as a bolus of 0.3 microgram.kg-1, 5 min before induction of anesthesia, and infused at a constant rate of 0.5 microgram.kg-1.h-1 throughout the study. ⋯ The models of Gepts et al. (Anesth Analg 1987; 66:1256-1263, Anaesthesia 1988; 43(suppl):8-13), Tackley et al. (Br J Anaesth 1989;62:46-53), and Cockshott (Postgrad Med J 1985;61:55), derived from healthy patients receiving continuous propofol infusions, provided the best agreement between expected and measured propofol concentrations; they showed bias and inaccuracy lower than 17%. In conclusion, the accurate prediction of blood propofol concentrations from different continuous infusion rates in ASA I or II patients requires the selection of appropriate pharmacokinetic models derived from similar categories of patients and using a similar technique of propofol administration. However, in clinical practice, the selection of a specific set among the appropriate models is balanced by the interindividual variability in blood propofol concentrations adjusted to clinical effects.
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J Neurosurg Anesthesiol · Apr 1997
Case Reports Comparative StudySensitivity to vecuronium after botulinum toxin administration.
When used to treat focal dystonias, botulinum toxin may cause a transient impairment of neuromuscular transmission in muscles distant from those injected. These systemic effects are not clinically evident, but should not be ignored when patients are exposed to other drugs or conditions that also impair neuromuscular transmission. ⋯ Compared with that observed in 24 individuals who were free from neuromuscular problems, the patient's sensitivity to vecuronium was low 90 days after the seventh treatment with toxin and normal 8 days after the ninth. The possibility is considered that repeated treatments with the toxin may cause continuous remodeling of neuromuscular junctions and may cause the patient to develop some tolerance to the action of neuromuscular blockers.
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J Neurosurg Anesthesiol · Apr 1997
Effects of normo- and hypocapnic nitrous-oxide-inhalation on cerebral blood flow velocity in patients with brain tumors.
Nitrous oxide (N2O) use during anesthesia for intracranial procedures has been a subject of controversy in the past. To date, the isolated influence of N2O on mean cerebral blood flow velocity in the middle cerebral artery (VMCA) has not been investigated during hypocapnia in patients with brain tumors. We compared VMCA during normocapnic (ETCO2: 40 mm Hg) and hypnocapnic (ETCO2: 25 mm Hg) inhalation of air and 50% nitrous oxide in oxygen N2O/O2 in eight patients with unilateral brain tumors on both the tumor side and the healthy side. ⋯ Mean VMCA increased during normocapnic inhalation of N2O/O2 (tumor side: 86 +/- 16 cm sec-1; healthy side: 74 +/- 17 cm sec-1) when compared with air (tumor side: 72 +/- 18 cm sec-1; healthy side: 62 +/- 14 cm sec-1, p < 0.01), whereas during hyperventilation VMCA decreased on both sides (p < 0.001). Mean VMCA values were quite similar during hypocapnic inhalation of 50% N2O/O2 (tumor side: 50 +/- 12 cm sec-1; healthy side: 45 +/- 13 cm sec-1) and air (tumor side: 51 +/- 14 cm sec-1; healthy side: 45 +/- 12 cm sec-1). The data of our study suggest that in patients with cerebral tumors the N2O-induced increase in mean VMCA can be completely reversed by hyperventilation.
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J Neurosurg Anesthesiol · Apr 1997
Case ReportsHyperalgesia induced by high-dose intrathecal sufentanil in neuropathic pain.
The patient had lower lumbar arachnoiditis as part of a failed back surgery syndrome. Two years after discectomy, she still suffered from left lumbosciatic pain despite various invasive treatments. Psychologic impairment could be excluded. ⋯ Increasing the dose to 50 mg daily could only be supported for 3 h. Sufentanil was stopped and saline started, after which the evoked hyperalgesia disappeared. It is concluded that relatively high doses of sufentanil may induce hyperalgesia in patients with arachnoiditis and neuropathic pain.
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J Neurosurg Anesthesiol · Apr 1997
Comparative StudyThe influence of acute and chronic alcohol treatment on brain edema, cerebral infarct volume and neurological outcome following experimental head trauma in rats.
The aim of this study was to determine the influence of acute and chronic ethanol treatment on neurological outcome following head trauma in rats. Eight-two Sprague-Dawley rats were divided into 10 groups. Four groups received sham head trauma (surgical incision of the scalp but no trauma) and were treated with (A) nothing, (B) chronic ethanol (6% ethanol in drinking water for 40 days), (C) acute ethanol 1.5 g/kg, intraperitoneally (IP) and (D) acute ethanol 3 g/kg IP. ⋯ Specific gravity was also lower in the acute ethanol-treated groups compared with no ethanol, chronic ethanol, and acute ethanol plus ketamine groups (p < 0.03). Based on these observations, we conclude that in this rat head trauma model acute ethanol treatment increases mortality, neurological deficit, hemorrhagic necrosis volume, and brain edema. On the other hand, chronic ethanol treatment has no apparent effect and ketamine treatment does not counteract the effect of acute ethanol treatment.