Journal of neurosurgical anesthesiology
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J Neurosurg Anesthesiol · Jan 2003
Clinical TrialBrain tissue oxygen monitoring for assessment of autoregulation: preliminary results suggest a new hypothesis.
Brain tissue oxygen monitoring (P(ti)O2 (Neurotrend, Codman, Germany) was employed in addition to standard intracranial pressure (ICP) and cerebral perfusion pressure (CPP) monitoring in seven patients with severe neuronal damage of heterogeneous etiology. The correlation between P(ti)O2 changes and CPP fluctuations during periods of 30 minutes were analyzed, when CPP was above 70 mmHg and lower than 100 mmHg. A new ratio, the CPP-oxygen-reactivity (COR) index was calculated as COR=delta p(ti)O2 %/delta CPP%. ⋯ The preliminary data suggest that COR values above "1" might be pathologic. However, the reported sample sizes are too small to provide sufficient statistical power to justify inferential statistical analyses. As such, results are presented with descriptive statistics only, and should be regarded as a hypothesis.
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J Neurosurg Anesthesiol · Jan 2003
Evaluation of the safety of recent surgical microscopes equipped with xenon light sources.
Although recent surgical microscopes for neurosurgery are equipped with xenon light sources to obtain bright fields of vision, the safety of a xenon beam, which has strong energy intensity in a long ultraviolet light, for cortical neurons has not been evaluated. Cranial windows were made in the parietal bones of gerbils. The skull of each gerbil was covered with warmed saline (0.5 mm in depth) to maintain the brain temperature. ⋯ Because the highest energy levels of 365-nm ultraviolet rays emitted from surgical microscopes measured in the present study (0.379 mwatts/cm (2)) were much closer to the dose causing 0% damage than to the dose causing 9% damage, the risk of neuronal injury occurring during microsurgery could be negligible. However, care should be taken in patients who take medicine classified as photosensitizing agents, such as diphenylhydantoin, which are thought to concentrate ultraviolet energy. The use of saline over the cortical surface may be beneficial for reducing the detrimental effects of 365-nm ultraviolet light.
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J Neurosurg Anesthesiol · Oct 2002
Clinical TrialThe low normothermia concept--maintaining a core body temperature between 36 and 37 degrees C in acute stroke unit patients.
Elevated body temperature increases mortality and worsens outcome in acute stroke patients. In animal models of stroke, even slight hypothermia was shown to be neuroprotective. Pharmacological treatment alone (paracetamol, metamizol) usually fails to lower core body temperature below 37 degrees C. ⋯ Continuous body core temperature reduction of 1-2 degrees C may safely be attained by a cooling mattress in nonventilated stroke unit patients. Critically high temperature values can be avoided. The neuroprotective potential of this method has to be assessed in a controlled trial.
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J Neurosurg Anesthesiol · Oct 2002
Case ReportsCerebral injury predicted by transcranial Doppler ultrasonography but not electroencephalography during carotid endarterectomy.
When shunts are selectively used during carotid endarterectomy, the adequacy of collateral cerebral blood flow (CBF) after the carotid artery is clamped is determined by monitors based on different physiologic measurements. In this series of three patients, we used electroencephalography (EEG) to measure neuronal electrical activity and transcranial Doppler ultrasonography (TCD) to measure CBF velocity. In each of our cases, the EEG was unchanged from preclamp values, while TCD CBF velocity was dramatically reduced. All three patients had transient neuropsychometric or neurologic changes after surgery, which resolved.
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J Neurosurg Anesthesiol · Jul 2002
Dexmedetomidine may impair cognitive testing during endovascular embolization of cerebral arteriovenous malformations: a retrospective case report series.
After the reported successful use of dexmedetomidine to sedate patients in the intensive care unit without respiratory depression, we began to use dexmedetomidine for interventional neuroradiologic procedures. We report on five patients who had dexmedetomidine administered for sedation during embolization of cerebral arteriovenous malformations. All patients were comfortably sedated and breathing spontaneously. ⋯ They were still unable to undergo cognitive testing 45 minutes after the infusion was stopped. In contrast, 10 minutes after the discontinuation of the infusion of propofol, all patients were awake, alert, cooperative, and able to undergo cognitive testing without difficulty. In conclusion, on examination of five non-randomly selected case records, we found that dexmedetomidine significantly prevented neurologic and cognitive testing.