Electrical admittance cuff for non-invasive and simultaneous measurement of haematocrit, arterial pressure and elasticity using volume-oscillometric method

  • K. Yamakoshi
  • S. Tanaka
  • H. Shimazu
Blood Pressure

DOI: 10.1007/BF02523335

Cite this article as:
Yamakoshi, K., Tanaka, S. & Shimazu, H. Med. Biol. Eng. Comput. (1994) 32(Suppl 1): S99. doi:10.1007/BF02523335

Abstract

An improved technique based on the electrical admittance cuff was designed for the non-invasive measurement of haematocrit (Hct), together with blood pressure (BP) and arterial elasticity represented as volume elastic modulus (Ev), in human fingers. This device is made of a rigid annular chamber installed with a surrounding thin-walled tube (cuff), which is filled with electrolyte solution. A tetrapolar method is used to detect the admittance signals, both in the solution and in a finger segment placed through the cuff. With this device, it is theoretically shown that the resistivity of blood flowing into the segment is equal to that of the solution multiplied by the ratio of the admittance variation in the solution to that in the segment. Thus, the blood resistivity and therefore Hct can be non-invasively determined from the electrolyte resistivity and these two admittance variations. On the other hand, BP and Ev are also simultaneously measured from the admittance signals following the gradual change of the chamber pressure based on the volume-oscillometric method. Experiments were successfully made in 14 subjects, showing that the indirect Hct values agreed well with the direct values obtained from sampled blood and that this simle technique was significant for the non-invasive ad simultaneous measurement of these physiological variables.

Keywords

Arterial elasticity Blood pressure Electrical admittance cuff Electrical parallel model Haematocrit Non-invasive and simultaneous measurement Volume-oscillometric method 

Copyright information

© IFMBE 1994

Authors and Affiliations

  • K. Yamakoshi
    • 1
  • S. Tanaka
    • 2
  • H. Shimazu
    • 3
  1. 1.Research Institute for Electronic ScienceHokkaido UniversitySapporoJapan
  2. 2.Institute for Medical and Dental EngineeringTokyo Medical and Dental UniversityJapan
  3. 3.Department of PhysiologyKyorin University School of MedicineJapan