Acta neurochirurgica. Supplement
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Acta Neurochir. Suppl. · Jan 1998
Multimodal hemodynamic neuromonitoring--quality and consequences for therapy of severely head injured patients.
Fifty-five head injured patients (GCS < 8) were studied at an average of 7.5 +/- 3.4 days on the ICU to check quality of hemodynamic monitoring and the consequences for therapy. Multimodal neuromonitoring included intracranial pressure (ICP), mean arterial pressure (MAP), cerebral perfusion pressure (CPP), endtidal CO2 (EtCO2) as well as brain tissue--pO2 (p(ti)O2), regional oxygen (rSO2) and jugular venous oxygen saturation (SjO2). Regional p(ti)O2 as well as global SjO2 were sensitive technologies to detect hemodynamic changes. ⋯ Longterm-measurements of rSO2 using near infrared spectroscopy reached, if possible, a restricted reliability (good data quality up to 70%) and sensitivity in comparison to p(ti)O2. Especially p(ti)O2 enabled detection of critical p(ti)O2 (< 15 mm Hg) in up to 50% frequency during the first days after trauma and a second peak after day 6 to 8 according to evidence of CPP insults. Knowledge of baseline p(ti)O2 and CO2-reactivity allowed minimizing risk of ischemia by induced hyperventilation and improvement on cerebral microcirculation after mannitol administration could be individually recognized.
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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
Incidence of intracranial hypertension after severe head injury: a prospective study using the Traumatic Coma Data Bank classification.
Intracranial hypertension (ICH) is a frequent finding in patients with a severe head injury. High intracranial pressure (ICP) has been associated with certain computerized tomography (CT) abnormalities. The classification proposed by Marshall et al. based on CT scan findings, uses the status of the mesencephalic cisterns, the degree of midline shift, and the presence or absence of focal lesions to categorize the patients into different prognostic groups. Our aim in this study was to analyze the ICP evolution pattern in the different groups of lesions of this classification. ⋯ 3 patients had a normal CT scan, and none of them presented intracranial hypertension. In diffuse injury type II, the ICP evolution may be quite different. Patients with bilateral brain swelling (Diffuse Injury III) have a high risk of increased ICP (63.2%). Although in our study the frequency of Diffuse Injury IV was low, all patients in this category had a refractory ICP. In the category of evacuated mass lesions, two thirds of the patients presented an intracranial hypertension. In one third, ICP was refractory to treatment. 85% of patients with a non-evacuated mass lesion showed an increased ICP.
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Acta Neurochir. Suppl. · Jan 1998
Comparative StudyUse of vasopressors to raise cerebral perfusion pressure in head injured patients.
Cerebral ischemia due to low cerebral perfusion pressure (CPP) is the most important secondary effect of severe head injury. There is consensus regarding the maintenance of this pressure at levels above 70 mm Hg. One way to elevate CPP is by increasing mean arterial pressure (MAP). ⋯ The results were: a) the increase of MAP effectively increased CPP without changes in intracranial pressure (ICP) and cerebral extraction of oxygen (CEO2); b) noradrenaline at a dose of 0.5 mg to 5 mg/h was effective and safe and might be considered the drug of choice; c) dopamine was not as effective at a high dose of 10 to 42.5 micrograms/kg/min; d) methoxamine given as a bolus was an effective way to control sudden decreases in MAP. It made the patients more responsive to dopamine. No important undesirable reactions occurred during the study.
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Acta Neurochir. Suppl. · Jan 1998
The relationship of pulsatile cerebrospinal fluid flow to cerebral blood flow and intracranial pressure: a new theoretical model.
An electrical-equivalent circuit model of the cerebrovascular system is proposed, components of which directly relate to cerebrospinal fluid (CSF) compartment compliance and the determination of intracranial pressure (ICP). The model is based on three premises: 1) Under normal, physiologic conditions, the conversion of pulsatile arterial to nonpulsatile venous flow occurs primarily as a result of arterial compliance. Nonpulsatile venous flow is advantageous because less energy is required to maintain constant flow through the venous system, which comprises 75-80% of total blood volume. 2) Dynamic CSF movement across the foramen magnum is the primary facilitator by which intracranial arterial expansion occurs. ⋯ An interference of transcranial CSF movement results in a decrease in cerebral blood flow (CBF) due to inertial effects impeding pulsatile venous flow. Feedback regulation in response to this decreased CBF leads to arteriolar vasodilatation (decreased resistance), thereby lowering the pressure difference between internal carotid and capillary pressures. Assuming no changes in the BBB potential, ICP increases linearly as capillary pressure increases.