Overview

Instrumentation for Noninvasive Assessment of Cardiovascular Regulation

Principal Investigator:
Richard J. Cohen, M.D., Ph.D.

Organization:
Massachusetts Institute of Technology

Technical Summary

It is critically important to be able to assess alterations in cardiovascular regulation during and after space flight. We developed instrumentation for the non-invasive assessment of such alterations that can be used on the ground and potentially during space flight. This instrumentation will be used by the Cardiovascular Alterations Team at multiple sites for the study of the effects of space flight on the cardiovascular system and the evaluation of countermeasures. In particular, the Cardiovascular Alterations Team anticipates using this instrumentation in conjunction with ground-based human bed-rest studies and during application of acute stresses e.g., tilt, lower body negative pressure, and exercise. In addition, the Cardiovascular Alterations Team anticipates using this instrumentation to study astronauts before and after space flight and ultimately, during space flight. The instrumentation may also be used by investigators in other physiologic areas related to space flight, such as neurovestibular, human performance, chronobiology, and psycho-social behavioral, to measure changes in autonomic nervous function.

The instrumentation is based on a powerful new technology cardiovascular system identification (CSI) which has been developed in our laboratory. CSI provides a non-invasive approach for the study of alterations in cardiovascular regulation. This approach involves the analysis of second-to-second fluctuations in physiologic signals such as heart rate and non-invasively measured arterial blood pressure in order to characterize quantitatively the physiologic mechanisms responsible for the couplings between these signals. Through the characterization of multiple physiologic mechanisms, CSI provides a closed-loop model of the cardiovascular regulatory state in an individual subject. Until now application of CSI currently required off-line computerized analysis of recorded physiologic signals by an expert user. The user interacted iteratively with the computer to preprocess the data, select data segments for analysis, run the CSI analyses, and evaluate and interpret the results. Thus the availability of this technology was limited to highly expert users located in Professor Cohen's laboratory. In this project, we developed integrated instrumentation capable of acquiring the physiologic signals, performing the CSI analysis in a fully automated fashion, and displaying the results on-line. The design of this instrumentation will be such that users with minimal training (including astronauts and other NSBRI investigators) can perform CSI onsite, conveniently and effectively. The availability of this instrumentation is essential for effectively studying the cardiovascular effects of space flight and for the subsequent development and evaluation of appropriate countermeasures. In particular this instrumentation will be used by the Cardiovascular Alterations Team in the study and development of countermeasures to the development of post-flight orthostatic hypotension. The development of such instrumentation may also have significant clinical impact on the diagnosis and treatment of patients with a variety of cardiovascular and neurological disorders.

This project's funding ended in 2000