Cardiovascular System Identification

The Cardiovascular System Identification (CSI) technique evaluates the relation between second-to-second fluctuations in physiological signals, such as heart rate (HR), arterial blood pressure (ABP), and instantaneous lung volume (ILV), to enable dynamic assessment of important physiological mechanisms without perturbing normal system operation.

This work has several applications:

After exposure to microgravity, astronauts often find it difficult to assume the upright posture on their return to Earth, as evidenced by lightheadedness (presyncope) or fainting (syncope). This phenomenon is referred to as microgravity-induced orthostatic intolerance (OI). We apply the CSI technique to quantify sympathetic and parasympathetic responsiveness with regard to HR regulation. The objective of this work is to study the effect of simulated microgravity on cardiovascular autonomic control and its association with OI. In addition, we evaluate the possibility of predicting microgravity-induced OI using only baseline measures.

This technique may also provide the first, noninvasive means for studying the various cardiovascular parameters in humans during health and disease (e.g., peripheral autonomic neuropathies).