ASSESSMENT OF THE HEMODYNAMIC REGULATION TYPE USING A FUZZY CLASSIFICATION TOOLBOX

Noninvasive methods are available to detect heart rate, systolic heart function and blood pressure, on a beat-to-beat basis at rest and duri ng standardized tests. Hence, a multivariate approach that allows more insight into the capacity of the cardiovascular system can be realize d for clinical routine. Electrocardiography, the first time derivative of the transthoracic impedance (dZdt), the basal impedance (Zo), and the finger arterial blood pressure were measured beat-to-beat in patie nts in supine body positions (7 min). The physiological signals mere t ransferred to an IBM PC and analyzed after analog-to-digital conversio n (sample rate 200 Hz). Upper arm blood pressure was measured every 3 min using an automated oscillometric device. The mean values of heart rate, arterial blood pressure at the upper arm and at the finger, and systolic heart function (maximum of the first time derivative of the i mpedancecardiogram divided by the basal impedance, dZdt/Zo) were analy zed for 110 healthy, male volunteers who were investigated consecutive ly. To characterize functional classes at rest, a fuzzy classification toolbox was used. Five classes were found that included normotensives and nontreated mild hypertensives (n = 32). The fuzzy pattern of each cluster was described using four out of a variety of parameters (body mass index, mean arterial pressure, mean arterial pressure at the fin ger, dZdt/Zo). Low or normal mean arterial pressure and high or normal volume blood flow was obtained mostly in young persons with normal bo dy composition (group I and II). Groups III-V seem to reflect the chan ges of the cardiovascular interrelationship caused by increasing aorti c input impedance, peripheral resistance, and decreased systolic left ventricular function, with a transition state of normal or even high f low values against increased afterload (group III). The groups illustr ate hemodynamic regulation caused by individual patterns of autonomic efferences and target organ response. The obtained knowledge about dif ferent hemodynamics at rest allows us to adapt therapy procedures to i ndividual patients.