ABSTRACT
A fully automated system for computer supported analysis of cardiovascular parameters on the basis of impedance technique, which is confined to the analysis of relative changes of stroke volume and cardiac output, has been developed and tested. The evaluation showed good agreement between automatic and manual calculation. As the whole computational procedure is done by software, which is written in a common language (BASIC), a maximum of flexibility and portability is guaranteed. Estimation of relative changes of stroke volume and cardiac output as well as peripheral blood flow is possible without any manual interaction. Extension from physiological measurement of healthy individuals to clinical application has been started.
Subject(s)
Cardiac Output , Cardiography, Impedance/methods , Diagnosis, Computer-Assisted/methods , Plethysmography, Impedance/methods , Programming Languages , Signal Processing, Computer-Assisted , Software Validation , Stroke Volume , Evaluation Studies as Topic , Humans , Microcomputers , Reproducibility of Results , Vascular ResistanceABSTRACT
In six subjects thermograms of the thighs and the forearms were taken before, during and after 10 min ergometer exercise at 100 W at an ambient temperature of 23 degrees C. During exercise, an intra-individually constant and reproducible skin temperature pattern with local temperature differences exceeding 3 degrees C evolved. Reactions after external local cooling or after occlusion of blood flow and measurements with a laser Doppler-flowmeter showed dispersed convective heat transport to be the source of this irregular pattern. Temperature differences of 3.6 degrees C and deviations of blood flow in the skin microcirculation of 300% within a distance of a few centimetres reduce the value of single-spot measurements of skin temperature with reference to the whole extremity.
