CO2 CEREBROVASCULAR REACTIVITY AS A FUNCTION OF PERFUSION-PRESSURE - A MODELING STUDY

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 autoregula tion to a higher range of CPP, as shown by this model, is a useful cha racteristic that facilitates the differentiation between normal and im paired autoregulation described previous in experimental studies. Dyna mic properties of cerebrovascular circulation derived from the relatio nship between pulse wave of CBF waveform and CPP have been analysed at different levels of PaCO2-phenomenon, being often described as depend ence of blood flow velocity pulsatility index on the autoregulatory re serve. The model was also used to interpret interhemispheric asymmetry of CBF reactivity to changes in arterial concentration of CO2 in pati ents with carotid artery stenosis.