- Title
- Evaluation of blood resistivity in vivo for impedance cardiography in man, dog and rabbit
- Creator
- Traugott, F. M.; Quail, A. W.; White, Saxon William
- Relation
- Medical & Biological Engineering & Computing Vol. 19, Issue 5, p. 547-552
- Relation
- http://link.springer.com/article/10.1007%2FBF02442767
- Publisher
- Springer
- Resource Type
- journal article
- Date
- 1981
- Description
- The accuracy of impedance cardiography for measurement of stroke volume (SVz) has been controversial. This could be, in part, due to the use in the Kubicek formula of the bench-determined blood resistivity (p)-haematocrit (Hct) relationship, which does not take into account factors such as complex blood-velocity movements. In the present study in vivo, p was calculated in dog, rabbit and man from the rearranged Kubicek formula, p = (SV. Zo2)/(L2. dZ/dt max T); the stroke volumes used in the calculation being derived at different Hcts in the different species from the independent techniques of electromagnetic flowmeter, direct Fick, and direct Fick and thermodilution, respectively. The in vivo p-Hct relationship is linear, inverse and nearly constant over the range of Hcts tested (dog 26–62%, man 31–48%, rabbit 37%). No significant difference exists between meanin vivo p values determined for the three species at corresponding haematocrits despite different thoracic anatomy and circulatory dynamics. Thus, the best estimate of mean p in vivo within the normal Hct range is 135Ωcm, the use of which will result in a SVz accuracy of better than ± 10%.
- Subject
- blood resistivity in vivo; cardiac output; haematocrit; impedance cardiography; stroke volume
- Identifier
- http://hdl.handle.net/1959.13/938746
- Identifier
- uon:12668
- Identifier
- ISSN:0140-0118
- Language
- eng
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