A COMPUTING SYSTEM FOR THE CLINICAL AND EXPERIMENTAL INVESTIGATION OFCEREBROVASCULAR REACTIVITY

We present a computing system for the recording and on-line analysis o f analogue signals derived from bedside cerebrovascular monitors in di fferent pathophysiological conditions. These include arterial blood pr essure and oxygen saturation, end-tidal carbon dioxide concentration, cerebral blood flow velocities using transcranial Doppler ultrasonogra phy, and concentration changes in cerebral oxy-and deoxyhaemoglobin fr om near infrared spectroscopy. Configuration and analysis adopts arith metic expressions of different signal processing functions, various st atistical properties for each signal, frequency spectrum analysis usin g fast Fourier transformation, and correlation/cross-correlation. The software offers off-line analysis of non-invasive tests of cerebrovasc ular reactivity. Several examples of clinical assessment of cerebrovas cular reactivity are presented, including cerebral haemodynamic stress tests which employ carbon dioxide, acetazolamide, the breath holding test, leg cuff inflation and deflation, and transient carotid artery c ompression. Application within the experimental setting with induced h aemorrhagic hypotension can also be used.