Estimation of blood pressure-related parameters by electrical impedance measurement.
In 13 healthy volunteers a computerized experimental set-up was used to measure the electrical impedance of the upper arm at changing cuff pressure, together with the finger arterial blood pressure in the contralateral arm. On the basis of a model for the admittance response, the arterial blood volume per centimeter length (1.4 +/- 0.3 ml/cm), the venous blood volume as a percentage of the total blood compartment (49.2 +/- 12.6%), and the total arterial compliance as a function of mean arterial transmural pressure were estimated. The effective physiological arterial compliance amounted to 2.0 +/- 1.3 microliters.mmHg-1.cm-1 and the maximum compliance to 33.4 +/- 12.0 microliters.mmHg-1.cm-1. Additionally, the extravascular fluid volume expelled by the occluding cuff (0.3 +/- 0.3 ml/cm) was estimated. These quantities are closely related to patient-dependent sources of an unreliable blood pressure measurement and vary with changes in cardiovascular function, such as those found in hypertension. Traditionally, a combination of several methods is needed to estimate them. Such methods, however, usually neglect the contribution of extravascular factors.
Muntinga
J H
JH
Department of Medical Physiology, University of Groningen, The Netherlands.
Visser
K R
KR
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001132:Arm / Q000098:blood supply; D001158:Arteries / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D001810:Blood Volume / Q000502:physiology; D003187:Compliance; D004553:Electric Conductivity / Q000502:physiology; D005260:Female; D006321:Heart / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow / Q000502:physiology; D014661:Vasoconstriction / Q000502:physiology