Two-channel bioimpedance monitor for impedance cardiography

In this paper we introduce our conception of a two-channel bioimpedance monitor for the impedance cardiography. We describe the design of a homemade device which is based on a direct digital synthesizer and a digital down converter. This solution enables us to obtain a high-quality bioimpedance signal, which can be used for computing the cardiac output beat per beat. It further enables us to analyze impedance phase changes beat per beat. Our device allows simultaneous measuring of complex impedance in two arbitrary directions on human/animal body without any interference between channels. The setting of the main parameters of the measurement like the amplitude and the frequency of the measurement current depends on the user.