Biomedical subjects

C Stick

Publications and source records attributed to C Stick.

21 records · Page 2Linked to original sources

PubMed1981

[Impedance plethysmography: measurements of volume changes of human limbs caused by capillary filtration (author's transl)].

The idea of this paper is to examine, after a discussion of the theoretical foundations, to what extent impedance plethysmography enables us to measure changes in the volume of the human extremities caused by capillary fluid filtration. Possibilities of error shown up in this paper - e. g., resistance of the skin, phase shift between current and voltage, the influence of specific resistance, dependence on temperature - partially confine the applicability of impedance plethysmography to comparative relative measurements. In these cases and in full view of the possibilities of error this method offers the advantage of absolutely pressureless measurement and the opportunity to extend this procedure to days.

Capillaries↗

PubMed1978

[The reproducibility of stroke-volume measurements by impedance cardiography. A critical analysis (author's transl)].

40 determinations of the stroke volume were carried out by impedance cardiography in one and the same subject. The stroke volume varied between 136 and 209 ml (x, x = 169 ml, S.D. = 17.5 ml). The mean error was in the same range as obtained by the Fick principle or by dye-dilution technique as referred to the literature. However, analysing the factors affecting the variability of the determined stroke volumes we may infer, the Kubicek formula for stroke volume is neither theoretically nor empirically sufficiently proved. A quantitative determination of the stroke volume or of any other circulatory quantity by the impedance cardiography seems to be impossible by our present method of procedure.

Cardiac Output↗

PubMedDate not supplied

Impedance cardiography the reproducibility of stroke volume measurements under conditions of mass examination.

The stroke volume at rest of 81 test subjects with no evident cardiac or circulatory dysfunction was determined by impedance cardiography and the measurements were repeated after 11 weeks. In order to attain comparable and reproducible conditions, 44 test subjects were chosen who showed heart rates at rest not higher than 83 beats per min, and whose changes in heart rate between the two tests were not greater than 11 beats per min. The stroke volumes determined by impedance cardiography are greater than those measured with the invasive methods reported by other authors. If the electrodes are removed between the tests sufficient reproducibility is not obtained. It is concluded that determinations of stroke volume by impedance cardiography as described in the literature are only suitable for detecting directional changes when the electrodes are left in place. It is impossible to obtain comparable data with electrodes once removed and replaced for the second measurement. Impedance cardiography is based on theoretical assumptions which do not permit estimation of errors affecting the measurement.

Cardiac Output↗