Design of an instrumentation system for a neurocardiology laboratory

Neurocardiology laboratories must have means to acquire and characterize neurally mediated cardiovascular responses. Since neurocardiology is an emerging field, there is a lack of standardization, and therefore there is a need for specific, flexible and customized instrumentation to appropriately measure a representative set of cardiorespiratory signals, from which the amount of autonomic modulation can be derived. A modular instrumentation system is presented in this paper, with the flexibility characteristics associated with virtual instrumentation systems. Two acquisition modules are presented: a three channel high resolution electrocardiographic module (HRECG); and an impedance cardiography module (ICG). These modules are based on strict considerations of linearity and noise reduction, with the purpose of obtaining an optimal signal. In each module, adjustable gain, electrode wiring guarding, and synchronized transformer-based DC/DC converter and capacitive isolation are used. These characteristics allow the development of an acquisition system easily expandable according to the application, with the possibility of controlling external devices.