Transcephalic electrical impedance in the study of cerebral circulation in a juvenile pig model

Cerebral blood-flow monitor for use in neonatal intensive care units

The implementation of a real-time multichannel system for monitoring cerebral blood-flow is described. The instrument relies on a completely modular architecture and is based on the principle of measuring the electrical impedance between a number of periodically sensed electrode pairs positioned around the subject's head. The whole setup is controlled by a host computer that performs several functions, such as real-time acquisition, analysis, display and data logging. Two operating options can be chosen by the user: a normal mode that allows continuous monitoring and a triggered mode in which the measurement cycle is automatically started by the occurrence of a preset condition in some other circulatory signal, e.g. the permanently available ECG signal. The design is considerably user-friendly and embodies a number of special safety precautions to take account of the peculiar condition of patients, usually newborn infants hospitalized in intensive care units.