Acta neurochirurgica. Supplement
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Acta Neurochir. Suppl. · Jan 2012
Continuous quantitative monitoring of cerebral oxygen metabolism in neonates by ventilator-gated analysis of NIRS recordings.
Oxidative stress during fetal development, delivery, or early postnatal life is a major cause of neuropathology, as both hypoxic and hyperoxic insults can significantly damage the developing brain. Despite the obvious need for reliable cerebral oxygenation monitoring, no technology currently exists to monitor cerebral oxygen metabolism continuously and noninvasively in infants at high risk for developing brain injury. ⋯ By using cerebral near-infrared spectroscopy and signals from conventional ventilators, along with arterial oxygen saturation, we derive continuous (breath-by-breath) estimates of cerebral venous oxygen saturation, cerebral oxygen extraction fraction, cerebral blood flow, and cerebral metabolic rate of oxygen. The resultant estimates compare very favorably to previously reported data obtained by non-continuous and invasive means from preterm infants in neonatal critical care.
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Acta Neurochir. Suppl. · Jan 2012
Comparative StudyComparison of a new brain tissue oxygenation probe with the established standard.
Continuous bedside brain tissue oxygenation (p(br)O(2)) monitoring using the Licox system is an established method for detecting secondary ischemia in comatose patients with acute brain injury. The purpose of the current study was to compare the newly introduced Raumedic p(br)O(2) probe with the established standard. ⋯ Our data suggest that the p(br)O(2) measurements of the two systems cannot be interchanged. Although we were unable to determine which system delivers more valid data, we do think that more rigorous testing is necessary before implementing the new probe in clinical routine.
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Acta Neurochir. Suppl. · Jan 2012
Assessment of cerebral autoregulation from respiratory oscillations in ventilated patients after traumatic brain injury.
Phase shift (PS) between oscillations in arterial blood pressure (ABP) and transcranial Doppler (TCD) cerebral blood flow velocity (CBFV) is thought to describe cerebral autoregulation. Ventilated patients show high amplitude and regular respiratory oscillations in ABP and CBFV, allowing reliable PS measurement. We analysed recordings of ABP, CBFV and intracranial pressure (ICP) from 187 TBI patients treated at Addenbrooke's Hospital, Cambridge, UK, from 1993 to 1998. ⋯ PS was significant (p < 0.05) for PSm only. Respiratory PS responds to changes in CPP and RR and correlates weakly with CA. Respiratory PS may have some prognostic value for patients with TBI.
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Acta Neurochir. Suppl. · Jan 2012
Realization of a comprehensive non-invasive detection of intracranial pressure analyzer based upon FVEP and TCD.
Up to now, several methods, such as flash visual evoked potential (FVEP) and transcranial Doppler (TCD), have been studied with regard to assessing intracranial pressure (ICP) non-invasively. However, there are still no instruments that are readily available for non-invasive measurement of ICP in clinical practice. Based on the advantages of FVEP and TCD for ICP assessment, the two methods are synthesized to develop a specific instrument to non-invasively measure ICP more reliably and applicably, as the integration of FVEP and TCD overcomes the shortcomings of a single method of ICP measurement.
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Acta Neurochir. Suppl. · Jan 2012
Pulse amplitude and Lempel-Ziv complexity of the cerebrospinal fluid pressure signal.
The complexity of the intracranial pressure (ICP) signal decreases with intracranial hypertension in children with acute brain injury as well as during infusion studies in adults with hydrocephalus. In this study we have analysed the pressure signal obtained in the lumbar subarachnoid space during infusion testing. The pulse amplitude rises when the ICP is increased by additional external volume. Our objective was to determine the relative influence of the pressure range and pulse amplitude on the loss of complexity observed during infusion-related intracranial hypertension. ⋯ The pulse amplitude of the CSFP signal seems to be a major determinant of the waveform complexity.