Acta neurochirurgica. Supplement
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Acta Neurochir. Suppl. · Jan 1998
Increase in transcranial Doppler pulsatility index does not indicate the lower limit of cerebral autoregulation.
Transcranial Doppler pulsatility index was reported clinically to increase when cerebral perfusion pressure decreased, hypothetically marking the lower limit of cerebral autoregulation. We sought to investigate the relationship between pulsatility index, cerenbrovascular resistance, and cerebral perfusion pressure in various states of autoregulation in an animal model of moderate intracranial hypertension. ⋯ The increase in transcranial Doppler pulsatility index when cerebral perfusion pressure falls cannot be interpreted as a phenomenon able to mark the lower limit of cerebral autoregulation.
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Acta Neurochir. Suppl. · Jan 1998
Randomized Controlled Trial Comparative Study Clinical TrialICP during anaesthesia with sevoflurane: a dose-response study. Effect of hypocapnia.
In patients with a supratentorial cerebral tumor, an increase in sevoflurane concentration from 1.5% (0.7 MAC) to 2.5% (1.3 MAC) did not change the intracranial pressure (ICP) significantly (12 to 14 mm Hg (medians)). However, a significant increase in cerebral blood flow (CBF) from 29 to 39 ml/100 g/min (medians) was disclosed. During administration of sevoflurane 1.5% and 2.5%, a significant decrease in ICP (3.5 and 3.0 mm Hg (median) respectively) was found when PaCO2 was decreased by 0.8 kPa.
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Acta Neurochir. Suppl. · Jan 1998
Comparative Study Clinical TrialDual-switch valve: clinical performance of a new hydrocephalus valve.
The Dual-Switch valve (DSV) is the first construction on the market which changes between two different valve-chambers in parallel depending on the posture of the patient. In the lying position the valve acts like a conventional differential pressure valve, in the vertical position the high-pressure chamber only opens, when the pressure exceeds the hydrostatic pressure difference between the formanen of Monro and the peritoneal cavity. The new device has been implanted in 32 adult patients with hydrocephalus of different etiology. ⋯ Contrary to conventional differential-pressure valves, adjustable devices and other hydrostatic constructions like the Anti-Siphon-device (ASD) or Deltavalve, the DSV reliably controls the IVP independently of the posture of the patient, the CSF viscosity or the subcutaneous pressure. In contrast to the Orbis-Sigma-valve (OSV) or the Diamond-valve, the DSV does not control the flow but the physiological IVP avoiding the increased risk of mechanical failure. The results of this study give strong evidence that the shunt-therapy of adult hydrocephalic patients can be significantly improved by the DSV.
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Acta Neurochir. Suppl. · Jan 1998
Comparative StudyComparative effects of hypothermia, barbiturate, and osmotherapy for cerebral oxygen metabolism, intracranial pressure, and cerebral perfusion pressure in patients with severe head injury.
In order to select the optimal neurointensive treatment for patients with severe head injury and intracranial hypertension, the effects of hypothermia (HT), barbiturates (BT), and osmotic agents (OT) on focal and diffuse cerebral oxygen metabolism were evaluated by means of continuous monitoring of bifrontal regional oxygen saturation (rSO2), jugular bulb oxygen saturation (SjO2), jugular bulb temperature (Tjb), intracranial pressure (ICP), and cerebral perfusion pressure (CPP). ⋯ The therapeutic effects of hypothermia, barbiturates, and osmotherapy on cerebral oxygen metabolism and ICP/CPP are different according to the underlying pathological lesions of patients with severe head injury.
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Acta Neurochir. Suppl. · Jan 1998
Comparative StudyClinical evaluation of the Codman microsensor intracranial pressure monitoring system.
The use of the Camino fibre-optic subdural device for measuring Intracranial Pressure (ICP) in patients, has been shown to correlate well with recordings from the "gold standard" intraventricular fluid filled catheter [1]. Following this work, its use has become standard in the clinical monitoring of patients. More recently, laboratory studies have demonstrated accuracy, acceptable drift and high fidelity for the new Codman Microsensor ICP Transducer, a miniature strain gauge mounted on a flexible nylon catheter [3]. Its performance in patients, however, has yet to be fully assessed, in comparative studies. ⋯ These differences could in the majority of cases (excepting the negative drift) be explained by a constant offset of the Codman transducer, as described previously [6]. Further examination of this device is required.