Journal of neurosurgical anesthesiology
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J Neurosurg Anesthesiol · Apr 2000
The influence of positioning on spectroscopic measurements of brain oxygenation.
This study was designed to evaluate the influence of body position during neurosurgical and cerebrovascular operations on regional cerebral oxygen saturation (rSO2). Awake volunteers (group I; n = 14), anesthetized patients (group II; n = 48) undergoing lumbar discectomy, and 12 patients undergoing carotid endarterectomy (group III) with internal carotid artery (ICA) stenosis were studied. Anesthesia in the patient groups was performed with sevoflurane (1.1 Vol% insp.) in N2O2/O2 mixture (FiO2 0.4) rSO2 was monitored with a INVOS 4100 cerebral oxymeter (Somanetics Corporation, Troy, MI). ⋯ After turning the head to the ipsilateral side, this difference diminished. In contrast, turning the head toward the contralateral side, the rSO2 difference remained nearly constant, both values decreasing constantly throughout the observation period. In conclusion, after different positioning maneuvers awake and under anesthesia, alterations of rSO2 can be registrated by near-infrared spectroscopy (NIRS).
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J Neurosurg Anesthesiol · Apr 2000
Inhibitory effects of halothane, isoflurane, sevoflurane, and pentobarbital on the constriction induced by hypocapnia and bicarbonate in isolated canine cerebral arteries.
The effects of halothane, isoflurane, sevoflurane (0.5, 1 and 2 MAC) and pentobarbital (10(-5) M, 10(-4) M and 3 x 10(-4) M) on hypocapnia- and bicarbonate-induced constriction of isolated dog middle cerebral arteries were investigated in vitro. The isometric tension of isolated cerebral arterial rings was measured in an organ bath containing Krebs bicarbonate solution, aerated with 5% CO2 and 95% O2. Hypocapnia, induced by replacing the bathing solution with one that had been equilibrated with 2.5% CO2 and 97.5% O2, produced a sustained vasoconstriction (268 +/- 36 mg, mean +/- SEM). ⋯ Halothane (1 and 2 MAC) attenuated the constriction induced by hypocapnia to a greater extent than that induced by 15 mM KCl, whereas pentobarbital (10(-4) M and 3 x 10(-4) M) attenuated hypocapnia-induced constriction less than KCl-induced constriction. These results indicate that alkaline-induced constriction is more vulnerable to halothane than other volatile anesthetics and pentobarbital. The mechanisms of the inhibitory effects of halothane and pentobarbital on alkaline-induced cerebral vasoconstriction seem to differ; the inhibitory effect of pentobarbital, but not of halothane may be, in part, ascribed to its inhibitory effect on the Ca++ influx.
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J Neurosurg Anesthesiol · Jan 2000
Randomized Controlled Trial Comparative Study Clinical TrialPropofol anesthesia for craniotomy: a double-blind comparison of remifentanil, alfentanil, and fentanyl.
For patients undergoing craniotomy, it is desirable to have stable and easily controllable hemodynamics during intense surgical stimulation. However, rapid postoperative recovery is essential to assess neurologic function. Remifentanil, an ultra-short-acting mu-opioid receptor agonist, may be the ideal agent to confer the above characteristics. ⋯ There were no significant differences among the groups in the dose of propofol maintenance required, heart rate, or mean arterial pressure. However, the time to eye opening (minutes) was significantly shorter in the remifentanil compared to the alfentanil group (6+/-3; 21+/-14; P = 0.0027) but not the fentanyl group (15+/-9). We conclude that remifentanil is an appropriate opioid to use in combination with propofol during anesthesia for supratentorial craniotomy.
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J Neurosurg Anesthesiol · Jan 2000
Randomized Controlled Trial Comparative Study Clinical TrialEvaluation of acute normovolemic hemodilution for surgical repair of craniosynostosis.
This clinical report investigated the potential benefit of acute normovolemic hemodilution (ANH) as a blood-saving technique in the surgical repair of craniosynostosis. Over a 4-year period, 34 healthy children undergoing surgical repair of scaphocephaly or pachycephaly were randomly assigned to two groups of 17 patients each. Patients of the first group (ANH group) were submitted to ANH (target Ht: 25%) immediately before surgery and patients of the second group (Control group) were not. ⋯ Both groups were comparable regarding age, weight, type of craniosynostosis, duration of surgery, EBV, and preoperative Ht value. No difference was observed between ANH and Control groups in the number of patients who received homologous blood (15/17 and 14/17, respectively), in the amount of homologous blood transfused (17+/-4.7% and 19.6+/-6.3% of the EBV, respectively), and in the Ht value before hospital discharge (29.4+/-5.0% and 30.7+/-4.9%, respectively). In conclusion, this report suggests that ANH reduces neither the incidence of homologous transfusion nor the amount of homologous blood transfused in this series of children undergoing surgical repair of craniosynostosis.
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J Neurosurg Anesthesiol · Jan 2000
Randomized Controlled Trial Clinical TrialCerebrovenous blood temperature-influence of cerebral perfusion pressure changes and hyperventilation: evaluation in a porcine study and in man.
The objective of the first part of this study was to use an animal model to investigate the relationship between temperature in the cerebrovenous compartment and cerebral perfusion pressure. In the second part of the study, the objective was to examine the influence of hyperventilation and hypothermia on jugular bulb temperature and body temperature in patients undergoing elective neurosurgery. Intracranial pressure was increased artificially by inflating an infratentorial supracerebellar placed balloon catheter in nine pigs under general anesthesia. ⋯ Before hyperventilation, cerebrovenous blood temperature was higher in 19 patients (+/- difference: 0.34 degrees C +/- 0.27) and equal or lower in five patients (difference: -0.08 degrees C +/- 0.11), than core body temperature. At the end of hyperventilation, the difference between cerebrovenous blood temperature and core body temperature increased (+0.42 degrees C +/- 0.24) in those 19 patients who had started with a higher cerebrovenous blood temperature and decreased (-0.10 degrees C +/- 0. 18) in the other five patients. Both studies demonstrated that the temperature of cerebrovenous blood is influenced by maneuvers which are supposed to decrease cerebral blood flow.