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  • 1
    Electronic Resource
    Electronic Resource
    CO2 cerebrovascular reactivity as a function of perfusion pressure — a modelling study (1993)
    Springer
    Acta neurochirurgica 121 (1993), S. 159-165 
    Details
    ISSN: 0942-0940
    Keywords: Cerebral blood flow ; autoregulation ; cerebral perfusion pressure ; carbon dioxide ; computer modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A mathematical model is described that demonstrated the properties of cerebral vascular resistance and compliance expressed as a function of cerebral perfusion pressure (CPP) and arterial CO2 partial pressure (PaCO2). The hypercapnic induced shift of the lower limit of autoregulation to a higher range of CPP, as shown by this model, is a useful characteristic that facilitates the differentiation between normal and impaired autoregulation described previously in experimental studies. Dynamic properties of cerebrovascular circulation derived from the relationship between pulse wave of CBF waveform and CPP have been analysed at different levels of PaCO2-phenomenon, being often described as dependence of blood flow velocity pulsatility index on the autoregulatory reserve. The model was also used to interpret interhemispheric asymmetry of CBF reactivity to changes in arterial concentration of CO2 in patients with carotid artery stenosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01809269
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Significance of intracranial pressure waveform analysis after head injury (1996)
    Springer
    Acta neurochirurgica 138 (1996), S. 531-542 
    Details
    ISSN: 0942-0940
    Keywords: Head injury ; intracranial pressure ; monitoring ; outcome ; waveform analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors have investigated the relationships between the amplitude of the ICP pulse wave, the mean values of ICP and CPP, and the outcome of 56 head injured ventilated patients. The ICP was monitored continuously using a Camino transducer (35 patients) or subdural catheter (21 patients). The mean Glasgow Coma Score was 6 (range 3–13; 5 patients had a GCS 〉 8 after resuscitation). Patients were grouped according to their Glasgow Outcome Score assessed at 12 months after injury. The amplitude of ICP pulse waveform was assessed using the fundamental harmonic of the pulse waveform (AMP) to avoid distortion caused by different frequency responses of the pressure transducers used in the study. Statistical analysis revealed that in patients with fatal outcome the ICP pulse amplitude increased when the mean ICP increased to 25 mmHg and then began to decrease. The upper breakpoint of the AMP-ICP relationship was not present in patients with good/moderate outcome. The moving correlation coefficient between the fundamental harmonic of ICP pulse wave and the mean ICP (RAP: R-symbol of correlation between A-amplitude and P-pressure) was introduced to describe the time-dependent changes in correlation between amplitude and mean ICP. The RAP was significantly lower in patients who died or remained in the vegetative state. In 7 patients who died from uncontrollable intracranial hypertension RAP was oscillating or decreased to 0 or negative values well before brain-stem herniation. The combination of an ICP above 20 mmHg for a period longer than 6 hours with low correlation between the amplitude and pressure (RAP 〈 0.5) was described as an predictive index of an unfavourable outcome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411173
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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