| Feedback control of total peripheral resistance (TPR) by the arterial and cardiopulmonary baroreflex systems is a well-known mechanism for short-term blood pressure regulation. Conventional methods for measuring this TPR baroreflex mechanism aim to quantify only the static gain value of one baroreflex system as it operates in open-loop conditions. As a result, the normal, dynamic functioning of the arterial and cardiopulmonary baroreflex control of TPR remains to be fully elucidated. To this end, we introduce a signal processing algorithm to identify the TPR baroreflex impulse response (and the dominant time constant of the systemic arterial tree) by analysis of small, beat-to-beat fluctuations in arterial blood pressure, cardiac output, and stroke volume. The algorithm may therefore provide a complete linear dynamic characterization of the TPR baroreflex under normal, closed-loop conditions from totally non-invasive measurement methods (e.g., arterial tonometry and Doppler ultrasound). We also demonstrate the validity of the algorithm with respect to realistic simulated data with known dynamic properties and conscious canine data before and after chronic arterial baroreceptor denervation. With further successful experimental testing, the signal processing algorithm may ultimately be employed to advance the basic understanding of the TPR baroreflex in both humans and animals in health and disease. |
