Assessment of stress-induced hemodynamic responses using multipurpose non-invasive continuous cardiovascular monitoring system.

In order to develop a simple and reliable assessment method of the stress induced psychosomatic and hemodynamic responses against various stress situations, especially for evaluating of the effectiveness of stress reduction methods, a multipurpose non-invasive continuous cardiovascular monitoring system was developed. The monitoring system could measure beat-by-beat finger blood pressure (SBP, MBP, DBP based on the volume-compensation method), cardiac output (CO, electrical admittance method), total peripheral resistance (TPR=MBP/CO), and the other hemodynamic related parameters (e.g. RR-interval, respiratory rate, pulse wave velocity, etc.). As controlled stress conditions, the human subjects would be exposed to the various stresses such as flash video display, electrical stimulation and so on. In this study, after 5 minutes resting, the stress induced hemodynamic responses were measured during 10-min presentation of floating vertical stripes image using 5 healthy subjects. The image presentation was discontinued when the subject gave his/her self-assessment due to considerable discomfort. The results showed that although BP increased during the presentation in all the subjects, there observed two types of cardiovascular responses; one is a type of increase in CO (or of almost unchanging or decrease in TRP), and the other of increase in TPR. These results strongly suggested that the detection of the change in TPR might be an important factor for the evaluation of stress conditions. Further investigations would be required for the reasons why these two types were observed in the same stressful condition.